Modern Solutions for Protection, Control, and Monitoring of Electric Power Systems, HJA Ferrer, EO Schweitzer

Tags: protection scheme, Ground fault protection, SEL relays, SEL, engineering networks, SCADA, network sniffer, Fault Protection, thermal protection, Generator Protection, Protection zone, Panel and Substation Control Enclosure, monitoring systems, Power System, fault detection, Manual control system, Communications system monitoring, Circuit design, Battery monitoring, Continuous monitoring, protection system
Content: Modern Solutions for Protection, Control, and Monitoring of Electric power systems Edited by Hйctor J. Altuve Ferrer Distinguished Engineer and Director of Technology for Latin America Schweitzer Engineering Laboratories, Inc. Edmund O. Schweitzer, III President Schweitzer Engineering Laboratories, Inc.
Schweitzer Engineering Laboratories, Inc., Pullman, WA 99163 © 2010 by Schweitzer Engineering Laboratories, Inc. All rights reserved.
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ISBN: 978-0-9725026-3-4
Publisher's Cataloging-in-Publication Data (Provided by quality books, Inc.)
Modern solutions for protection, control, and monitoring of electric power systems / edited by Hector J. Altuve Ferrer, Edmund O. Schweitzer, III. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-9725026-3-4 ISBN-10: 0-9725026-3-7
1. Electric power systems. 2. Electric power systems --Protection. 3. Electric power systems--Control. I. Altuve Ferrer, Hector J. II. Schweitzer, Edmund O.
TK1001.M63 2010
621.31 QBI10-600113
www.selinc.com
Dedication This book is dedicated to Carole Lowinger, with grateful appreciation for her many years of instructing SEL engineers in the fine art of writing clearly and concisely. Carole's work has been a vital contribution to this book. Carole's unfailing sense of humor and good cheer make her a pleasure to work with and to know. Acknowledgements This book is the result of a collective work. It reflects the cutting-edge technology developed by many SEL engineers. The book also extensively uses much of their technical literature, including technical papers, application guides, and instruction manuals. Some of these engineers directly contributed to the text while others reviewed the book and provided valuable improvements. Finally, many people contributed by enhancing the writing style, creating the figures, composing the book, and managing the book preparation process. We are deeply indebted to all of them.
Table of Contents Dedication ................................................................................................................................................................................ iii Acknowledgements .............................................................................................................................................................. iii List of Figures .....................................................................................................................................................................xvii List of Tables .....................................................................................................................................................................xxvii Preface.................................................................................................................................................................................. xxix 1 Looking to the Future...................................................................................................................................................... 1 1.1 Introduction ................................................................................................................................................................ 1 1.2 Time-Synchronized Measurements............................................................................................................................ 1 1.3 Distribution Systems .................................................................................................................................................. 2 1.4 Transmission Systems ................................................................................................................................................ 3 1.5 Transformers .............................................................................................................................................................. 4 1.6 Buses .......................................................................................................................................................................... 4 1.7 Generators .................................................................................................................................................................. 4 1.8 Wide-Area Systems.................................................................................................................................................... 5 1.9 Communications......................................................................................................................................................... 5 1.10 Information Processing .............................................................................................................................................. 6 1.11 Cybersecurity ............................................................................................................................................................. 6 1.12 Reliability and Testing ............................................................................................................................................... 6 1.13 Providing Complete Solutions ................................................................................................................................... 7 1.14 Asset Management ..................................................................................................................................................... 7 1.15 Call to Action ............................................................................................................................................................. 7 1.16 References .................................................................................................................................................................. 7 2 Time-Synchronized Systems........................................................................................................................................ 9 2.1 Introduction ................................................................................................................................................................ 9 2.2 Time-Synchronized Measurement Applications........................................................................................................ 9 2.3 Time Synchronization .............................................................................................................................................. 10 2.4 Time-Synchronized Phasors..................................................................................................................................... 12 2.4.1 Synchrophasor definition .................................................................................................................................. 12 2.4.2 Phasor angle reference for power system networks.......................................................................................... 12 2.4.3 Synchrophasors provide power system state information................................................................................. 13 2.4.4 Phasor angle and frequency are indicators of power system dynamic performance ........................................ 13 2.5 Combining Time-Synchronized Measurements With Protection, Control, and Monitoring ................................... 14 2.5.1 Advantages and architecture ............................................................................................................................. 14 2.5.2 Performance of synchrophasor measurements.................................................................................................. 15 2.5.2.1 Performance metrics .................................................................................................................................. 15 2.5.2.2 Visualizing synchrophasor measurements during fault and power swing conditions ............................... 16 2.5.2.3 Performance of synchrophasor measurements during faults ..................................................................... 17 2.5.2.4 Performance of synchrophasor measurements during power swings ........................................................ 19 2.6 Processing Synchrophasor Information ................................................................................................................... 20 2.6.1 Phasor data concentration ................................................................................................................................. 20 2.6.2 Synchrophasor-based protection, control, and monitoring ............................................................................... 20 2.6.2.1 Using real-time synchrophasor processors for advanced applications ...................................................... 20 2.6.2.2 Using directly communicated PMCUs ...................................................................................................... 22
vi 2.7 Synchrophasor Systems ............................................................................................................................................22 2.7.1 Time sources......................................................................................................................................................22 2.7.2 Phasor measurement devices.............................................................................................................................22 2.7.3 Synchrophasor processors .................................................................................................................................24 2.7.4 Communications networks ................................................................................................................................25 2.7.5 application software .........................................................................................................................................26 2.8 References.................................................................................................................................................................27 3 Distribution System Protection, Automation, and Monitoring ....................................................................29 3.1 Introduction...............................................................................................................................................................29 3.2 Limitations of Traditional Overcurrent Protection ...................................................................................................29 3.3 Modern Solutions for Distribution System Protection, Automation, and Monitoring .............................................30 3.3.1 New abilities......................................................................................................................................................30 3.3.2 More sensitive fault detection ...........................................................................................................................30 3.3.3 Faster fault clearing ...........................................................................................................................................30 3.3.4 Faster service restoration...................................................................................................................................31 3.3.5 Higher reliability and lower cost .......................................................................................................................32 3.4 Negative-Sequence Overcurrent Protection .............................................................................................................32 3.4.1 Negative-sequence overcurrent elements ..........................................................................................................32 3.4.2 Coordinating negative-sequence overcurrent elements with phase overcurrent elements................................33 3.5 Directional Overcurrent Protection...........................................................................................................................35 3.5.1 Directional elements for phase fault protection.................................................................................................35 3.5.2 Directional elements for ground fault protection ..............................................................................................35 3.5.2.1 Zero-sequence, current-polarized directional element ...............................................................................36 3.5.2.2 Negative-sequence, voltage-polarized directional element........................................................................36 3.5.2.3 Zero-sequence, voltage-polarized directional element...............................................................................36 3.5.2.4 32Q and 32V element operation for ground faults.....................................................................................36 3.5.2.5 Selecting the optimal directional element ..................................................................................................37 3.6 Improving Ground Fault Protection Sensitivity .......................................................................................................38 3.6.1 Ungrounded systems .........................................................................................................................................38 3.6.2 Resonant-grounded systems ..............................................................................................................................39 3.6.2.1 Wattmetric directional element ..................................................................................................................39 3.6.2.2 Incremental conductance element ..............................................................................................................40 3.6.3 High-resistance grounded systems ....................................................................................................................40 3.6.4 Effectively and low-impedance grounded systems ...........................................................................................41 3.6.4.1 Multigrounded systems ..............................................................................................................................41 3.6.4.2 Single-point grounded systems ..................................................................................................................42 3.7 Effect of Load Current..............................................................................................................................................42 3.7.1 Traditional backup sensitivity limitations .........................................................................................................42 3.7.2 Increasing sensitivity for three-phase faults ......................................................................................................42 3.7.3 Increasing sensitivity for phase-to-phase faults ................................................................................................42 3.7.4 Solving cold-load restoration current problems ................................................................................................43 3.7.5 Avoiding sympathetic tripping ..........................................................................................................................43 3.8 Distributed Generation Considerations.....................................................................................................................43 3.8.1 Interconnection protection.................................................................................................................................43 3.8.1.1 Local-area islanding detection ...................................................................................................................44 3.8.1.2 Wide-area islanding detection....................................................................................................................44 3.8.1.3 Complete interconnection protection .........................................................................................................45 3.8.1.4 SEL multifunction relays provide interconnection protection ...................................................................46 3.8.2 Distributed generation impacts utility system protection..................................................................................46 3.8.2.1 Line protection ...........................................................................................................................................46 3.8.2.2 Automatic reclosing and synchronism checking........................................................................................46 3.9 High-Speed Distribution System Protection.............................................................................................................46 3.10 Reducing Arc-Flash Hazards....................................................................................................................................47 3.10.1 Methods for reducing arc-flash hazards ............................................................................................................47 3.10.1.1 Avoiding the hazard area............................................................................................................................47 3.10.1.2 Installing arc-resistant switchgear..............................................................................................................47 3.10.1.3 Limiting the fault current ...........................................................................................................................47 3.10.1.4 Improving protection schemes ...................................................................................................................47
vii
3.10.2 Arc-flash protection .......................................................................................................................................... 47 3.10.2.1 Arc-flash time-overlight element............................................................................................................... 48 3.10.2.2 Arc-flash overcurrent element ................................................................................................................... 49 3.10.2.3 Event reports .............................................................................................................................................. 49 3.10.2.4 Sensor location........................................................................................................................................... 49 3.11 Distribution Automation .......................................................................................................................................... 49 3.11.1 Distribution automation objectives .................................................................................................................. 49 3.11.2 Automatic throw-over schemes ........................................................................................................................ 50 3.11.3 Distribution network fast-restoration schemes ................................................................................................. 51 3.11.4 Centralized distribution automation systems .................................................................................................... 51 3.11.5 Examples of distribution protection and automation systems .......................................................................... 52 3.12 Faulted Circuit Indicators......................................................................................................................................... 53 3.12.1 Benefits of faulted circuit indicators................................................................................................................. 53 3.12.2 Faulted circuit indicator applications................................................................................................................ 53 3.12.3 Combine faulted circuit indicators and relays for fast fault location................................................................ 54 3.12.4 Other application considerations....................................................................................................................... 54 3.12.5 Looking to the future......................................................................................................................................... 54 3.13 References ................................................................................................................................................................ 54
4 Transmission Line Protection ................................................................................................................................... 57
4.1 Introduction .............................................................................................................................................................. 57 4.2 Transmission Systems of Today and Tomorrow...................................................................................................... 57 4.3 Line Protection Principles ........................................................................................................................................ 59 4.4 Directional Overcurrent Protection .......................................................................................................................... 60 4.5 Distance Protection .................................................................................................................................................. 61 4.5.1 Basic principle................................................................................................................................................... 61
4.5.2 Distance protection schemes............................................................................................................................. 62
4.5.2.1 basic concepts............................................................................................................................................ 62
4.5.2.2 Reach settings ............................................................................................................................................ 62
4.5.2.3 Time-delay settings.................................................................................................................................... 62
4.5.3 Distance element input signals.......................................................................................................................... 63
4.5.4 Mho distance elements...................................................................................................................................... 64 4.5.4.1 Digital product phase comparators ............................................................................................................ 64 4.5.4.2 Mho characteristic derivation .................................................................................................................... 64 4.5.5 Quadrilateral distance elements ........................................................................................................................ 66 4.5.5.1 Quadrilateral element characteristic .......................................................................................................... 66
4.5.5.2 Reactance element ..................................................................................................................................... 66
4.5.5.3 Resistance elements ................................................................................................................................... 67
4.5.5.4 Directional element.................................................................................................................................... 68
4.5.6 Adaptive polarization........................................................................................................................................ 68
4.5.7 High-speed elements ......................................................................................................................................... 70
4.6 Sources of Distance Element Errors......................................................................................................................... 72 4.6.1 Infeed effect ...................................................................................................................................................... 72 4.6.2 Fault resistance.................................................................................................................................................. 73 4.6.3 Mutual coupling ................................................................................................................................................ 75 4.6.4 Load encroachment ........................................................................................................................................... 76
4.6.5 Effect of unfaulted phases................................................................................................................................. 76
4.6.6 Coupling-capacitor voltage transformer transients ........................................................................................... 77
4.6.7 Loss-of-potential ............................................................................................................................................... 78
4.7 Directional Comparison Protection.......................................................................................................................... 79 4.7.1 Basic schemes ................................................................................................................................................... 79
4.7.1.1 4.7.1.2 4.7.1.3 4.7.1.4 4.7.1.5
Direct underreaching transfer trip.............................................................................................................. 79 Permissive underreaching transfer trip ...................................................................................................... 79 Permissive overreaching transfer trip ........................................................................................................ 80 Directional comparison blocking............................................................................................................... 80 Directional comparison unblocking........................................................................................................... 80
4.7.2 Communications channels ................................................................................................................................ 80
viii 4.7.3 Scheme comparison...........................................................................................................................................81 4.7.3.1 Security and dependability .........................................................................................................................81 4.7.3.2 Speed and sensitivity..................................................................................................................................81 4.7.3.3 Complexity .................................................................................................................................................83 4.7.4 Hybrid directional comparison scheme .............................................................................................................83 4.8 Differential Protection ..............................................................................................................................................84 4.8.1 Communications channels and data alignment .................................................................................................84 4.8.2 Alpha-plane differential element.......................................................................................................................85 4.8.2.1 Representing power system conditions on the alpha plane........................................................................85 4.8.2.2 Alpha-plane differential element characteristic .........................................................................................86 4.8.2.3 Combining phase and sequence-component differential elements ............................................................87 4.8.3 Advanced differential protection for multiterminal lines..................................................................................87 4.8.4 Combining differential and directional comparison protection in one relay.....................................................89 4.9 Phase Comparison Protection ...................................................................................................................................89 4.10 Line Protection Sensitivity .......................................................................................................................................91 4.10.1 System grounding..............................................................................................................................................91 4.10.2 Relay sensitivity ................................................................................................................................................91 4.10.2.1 Ground directional overcurrent element sensitivity ...................................................................................91 4.10.2.2 Ground distance element sensitivity ..........................................................................................................91 4.10.2.3 Ground differential element sensitivity......................................................................................................92 4.10.3 Power system unbalances ..................................................................................................................................92 4.10.3.1 Unbalanced operating conditions ...............................................................................................................92 4.10.3.2 Unbalanced system elements .....................................................................................................................93 4.10.4 Instrument transformer accuracy.......................................................................................................................93 4.11 Series-Compensated Line Protection........................................................................................................................94 4.11.1 Voltage inversion affects directional discrimination.........................................................................................94 4.11.2 Current inversion affects directional and differential discrimination................................................................94 4.11.3 Series capacitors affect distance measurement..................................................................................................95 4.11.4 Directional comparison scheme security...........................................................................................................96 4.12 Single-Pole Tripping.................................................................................................................................................96 4.12.1 Faulted-phase identification ..............................................................................................................................96 4.12.2 Single-pole open considerations........................................................................................................................97 4.12.2.1 Distance elements.......................................................................................................................................97 4.12.2.2 Directional overcurrent elements ...............................................................................................................97 4.12.2.3 Differential elements ..................................................................................................................................98 4.12.3 Simultaneous faults ...........................................................................................................................................98 4.13 Power Swing Blocking and Out-of-Step Tripping ...................................................................................................99 4.13.1 Impedance-based power swing detection..........................................................................................................99 4.13.1.1 Power swing detection principle ................................................................................................................99 4.13.1.2 Detecting faults occurring during power swings......................................................................................100 4.13.1.3 Power swing blocking during the SPO period in SPT schemes...............................................................100 4.13.1.4 Application considerations.......................................................................................................................100 4.13.2 Swing-center-voltage method for power swing detection...............................................................................100 4.14 Thermal Protection .................................................................................................................................................101 4.15 Fault Locating.........................................................................................................................................................102 4.15.1 Single-ended methods .....................................................................................................................................102 4.15.1.1 Simple reactance method .........................................................................................................................103 4.15.1.2 Takagi method..........................................................................................................................................103 4.15.1.3 Modified Takagi method..........................................................................................................................103 4.15.2 Multiended method..........................................................................................................................................103 4.15.2.1 Application to two-terminal lines.............................................................................................................104 4.15.2.2 Application to multiterminal lines............................................................................................................104 4.16 References...............................................................................................................................................................104 5 Transformer Protection and Monitoring .............................................................................................................107 5.1 Introduction.............................................................................................................................................................107 5.2 Innovations in Transformer Protection and Monitoring.........................................................................................107 5.3 Transformer Differential Protection .......................................................................................................................108 5.3.1 Operation principle..........................................................................................................................................108
ix 5.3.2 Current scaling, phase-shift compensation, and zero-sequence current removal ........................................... 109 5.3.2.1 Current scaling......................................................................................................................................... 109 5.3.2.2 Transformer connections ......................................................................................................................... 110 5.3.2.3 Current phase-shift compensation ........................................................................................................... 110 5.3.2.4 Zero-sequence current removal ............................................................................................................... 111 5.3.3 Compensation for zero-sequence sources ....................................................................................................... 112 5.3.4 Differential current caused by magnetizing inrush, overexcitation, and CT saturation ................................. 112 5.3.4.1 Magnetizing inrush currents .................................................................................................................... 112 5.3.4.2 Transformer overexcitation...................................................................................................................... 113 5.3.4.3 CT saturation............................................................................................................................................ 113 5.3.5 Discriminating internal faults from inrush and overexcitation conditions ..................................................... 113 5.3.5.1 Harmonic-based methods ........................................................................................................................ 113 5.3.5.2 Wave-shape recognition methods............................................................................................................ 114 5.3.6 Microprocessor-based transformer differential elements ............................................................................... 115 5.3.6.1 Operation principle .................................................................................................................................. 115 5.3.6.2 Differential element ................................................................................................................................. 116 5.3.6.3 DC-ratio blocking logic ........................................................................................................................... 117 5.3.6.4 Relay-blocking logic................................................................................................................................ 117 5.3.6.5 Adaptive differential element .................................................................................................................. 118 5.3.6.6 Negative-sequence differential element................................................................................................... 118 5.4 Restricted Earth Fault Protection ........................................................................................................................... 120 5.4.1 Traditional restricted earth fault protection .................................................................................................... 121 5.4.2 Microprocessor-based relays improve restricted earth fault protection.......................................................... 121 5.5 Transformer Overexcitation Protection.................................................................................................................. 122 5.6 Transformer Overcurrent Protection ...................................................................................................................... 122 5.6.1 Transformer through-fault capability curves .................................................................................................. 123 5.6.2 Transformer overcurrent relay protection ....................................................................................................... 123 5.7 Transformer Sudden-Pressure and Gas-Accumulation Protection......................................................................... 125 5.7.1 Sudden-pressure protection............................................................................................................................. 125 5.7.2 Gas-accumulation protection .......................................................................................................................... 125 5.8 Combined Transformer and Bus Protection........................................................................................................... 126 5.9 Redundancy Considerations for Transformer Protection....................................................................................... 126 5.10 Transformer Monitoring......................................................................................................................................... 127 5.10.1 Microprocessor-based IEDs perform transformer monitoring functions........................................................ 127 5.10.2 Transformer thermal model ............................................................................................................................ 127 5.10.3 Insulation aging............................................................................................................................................... 130 5.10.4 Through-fault monitoring ............................................................................................................................... 130 5.10.5 Effect of through faults in transformer loss-of-life......................................................................................... 131 5.10.6 Integration of nonelectrical monitoring devices ............................................................................................. 132 5.11 References .............................................................................................................................................................. 132 6 Bus and Breaker-Failure Protection..................................................................................................................... 135 6.1 Introduction ............................................................................................................................................................ 135 6.2 Modern Solutions for Bus Protection..................................................................................................................... 135 6.3 Bus Arrangements .................................................................................................................................................. 136 6.4 Bus Protection Schemes ......................................................................................................................................... 136 6.4.1 Differential overcurrent protection ................................................................................................................. 137 6.4.2 High-impedance differential protection .......................................................................................................... 138 6.4.3 Percentage differential protection ................................................................................................................... 140 6.4.3.1 Basic concepts.......................................................................................................................................... 140 6.4.3.2 Advanced bus differential protection....................................................................................................... 141 6.4.4 Partial differential protection .......................................................................................................................... 144 6.4.5 Zone-interlocked protection............................................................................................................................ 144 6.4.5.1 Zone-interlocked, directional comparison blocking scheme ................................................................... 145 6.4.5.2 Zone-interlocked, simple blocking (fast bus-tripping) scheme ............................................................... 146 6.5 Breaker-Failure Protection ..................................................................................................................................... 148 6.5.1 Impact of breaker-failure protection on power system stability ..................................................................... 148 6.5.2 General considerations.................................................................................................................................... 148 6.5.3 Basic breaker-failure protection scheme......................................................................................................... 149
x 6.5.4 Breaker-failure protection scheme with consistent delay................................................................................149 6.5.5 Fast open-phase detectors................................................................................................................................150 6.5.6 Fast-reset breaker-failure protection scheme...................................................................................................151 6.5.7 Breaker-failure scheme with alternate initiation logic ....................................................................................151 6.5.8 Use different breaker-failure times for multiphase and single-phase-to-ground faults...................................152 6.5.9 Breaker-failure application in multifunction relays ........................................................................................153 6.5.10 Breaker-failure tripping ...................................................................................................................................153 6.6 Integrated Bus and Breaker-Failure Protection ......................................................................................................154 6.6.1 Protection zone selection.................................................................................................................................154 6.6.2 Bus differential and breaker-failure protection tripping..................................................................................156 6.7 References...............................................................................................................................................................156 7 Generator Protection and Monitoring..................................................................................................................159 7.1 Introduction.............................................................................................................................................................159 7.2 Modern Multifunction Generator Relays................................................................................................................159 7.3 Stator Fault Protection ............................................................................................................................................159 7.3.1 Phase fault protection ......................................................................................................................................159 7.3.2 Turn-to-turn fault protection............................................................................................................................161 7.3.3 Ground fault protection ...................................................................................................................................161 7.3.3.1 Generator grounding ................................................................................................................................161 7.3.3.2 Using the neutral voltage for protection...................................................................................................163 7.3.3.3 Using the third-harmonic voltage for protection......................................................................................163 7.3.3.4 100 percent stator ground fault protection ...............................................................................................164 7.3.3.5 Ground fault protection for low-impedance-grounded generators...........................................................164 7.4 Rotor Fault Protection.............................................................................................................................................165 7.5 Abnormal Operation Protection..............................................................................................................................167 7.5.1 Stator thermal protection .................................................................................................................................167 7.5.2 Field thermal protection ..................................................................................................................................168 7.5.3 Current unbalance protection ..........................................................................................................................168 7.5.4 Loss-of-field protection ...................................................................................................................................169 7.5.4.1 Effect of a loss of excitation on the generator and the power system......................................................169 7.5.4.2 Protection schemes...................................................................................................................................169 7.5.4.3 Loss-of-field element setting considerations............................................................................................170 7.5.5 Motoring protection.........................................................................................................................................172 7.5.6 Overexcitation protection ................................................................................................................................173 7.5.7 Overvoltage and undervoltage protection .......................................................................................................173 7.5.8 Abnormal frequency protection.......................................................................................................................174 7.5.8.1 Turbine abnormal frequency protection...................................................................................................174 7.5.8.2 Generator abnormal frequency protection................................................................................................174 7.5.8.3 Underfrequency load shedding versus generator underfrequency protection..........................................174 7.5.8.4 Underfrequency protection with SEL-300G and SEL-700G relays.........................................................174 7.5.9 Out-of-step protection .....................................................................................................................................175 7.5.9.1 Single-blinder protection scheme.............................................................................................................175 7.5.9.2 Double-blinder protection scheme ...........................................................................................................175 7.5.10 Inadvertent energization protection.................................................................................................................176 7.5.10.1 Generator damage ....................................................................................................................................176 7.5.10.2 Protection using other schemes ................................................................................................................176 7.5.10.3 Protection using dedicated schemes.........................................................................................................176 7.5.11 Backup protection............................................................................................................................................177 7.5.11.1 Voltage-supervised overcurrent elements ................................................................................................178 7.5.11.2 Distance elements.....................................................................................................................................178 7.5.11.3 Backup protection for ground faults.........................................................................................................179 7.6 Synchronism-Checking and Autosynchronizing Elements ....................................................................................179 7.7 P-Q Plane Based Generator Monitoring .................................................................................................................180 7.8 SEL-300G Relay Application Solutions.................................................................................................................180 7.9 References...............................................................................................................................................................181
xi 8 Wide-Area Protection, Control, and Monitoring .............................................................................................. 183 8.1 Introduction ............................................................................................................................................................ 183 8.2 Assessing Substation State and Topology.............................................................................................................. 183 8.2.1 Topology processor......................................................................................................................................... 184 8.2.2 Current processor ............................................................................................................................................ 184 8.2.2.1 Current measurement normalization and consistency check ................................................................... 184 8.2.2.2 Kirchhoff's current law verification ........................................................................................................ 184 8.2.2.3 Refining current measurements ............................................................................................................... 184 8.2.3 Voltage processor............................................................................................................................................ 185 8.3 Determining Power System State........................................................................................................................... 185 8.3.1 Traditional state estimation............................................................................................................................. 185 8.3.2 Synchrophasor-based state determination....................................................................................................... 186 8.3.3 Remote measurement supervision .................................................................................................................. 187 8.4 Detecting Power System Interarea Oscillations ..................................................................................................... 188 8.4.1 Signal modal representation............................................................................................................................ 188 8.4.2 Damping ratio ................................................................................................................................................. 188 8.4.3 Signal-to-noise ratio........................................................................................................................................ 189 8.4.4 Identifying interarea oscillation modes........................................................................................................... 189 8.4.5 Modal-analysis-based system integrity protection scheme............................................................................. 190 8.5 Black-Start Validation and Paralleling of Islanded Generators With a Large System .......................................... 190 8.6 Applying Synchrophasors to Predict Voltage Instability....................................................................................... 192 8.7 Automatic Generator Shedding Using Synchrophasor Angle Measurements ....................................................... 193 8.8 Use Synchrophasors to Back Up Transmission Line Protection............................................................................ 196 8.8.1 Faulted-phase identification............................................................................................................................ 196 8.8.2 Negative-sequence and zero-sequence current differential elements ............................................................. 196 8.8.3 Protection element performance ..................................................................................................................... 197 8.9 Distributed Bus Differential Protection.................................................................................................................. 198 8.9.1 Protection zone selection ................................................................................................................................ 198 8.9.2 Current differential element ............................................................................................................................ 198 8.9.3 Application example of bus differential protection ........................................................................................ 199 8.10 Power Swing and Out-of-Step Detection Using Synchrophasors.......................................................................... 199 8.10.1 Power swing detection .................................................................................................................................... 200 8.10.2 Out-of-step detection....................................................................................................................................... 200 8.10.3 Predictive out-of-step tripping ........................................................................................................................ 201 8.10.4 System integrity protection scheme for two-area power systems................................................................... 201 8.11 Synchrophasor-Based Islanding Detection ............................................................................................................ 204 8.12 System Integrity Protection Scheme Using MIRRORED BITS Communications .................................................... 205 8.13 Load Shedding to Prevent Voltage Collapse.......................................................................................................... 207 8.14 References .............................................................................................................................................................. 209 9 Power System Communications............................................................................................................................. 211 9.1 Introduction ............................................................................................................................................................ 211 9.2 Communications System Overview ....................................................................................................................... 211 9.2.1 Pilot protection................................................................................................................................................ 211 9.2.2 Substation and distribution automation........................................................................................................... 211 9.2.3 Wide-area protection and control.................................................................................................................... 211 9.2.4 SCADA and EMS ........................................................................................................................................... 212 9.2.5 Security ........................................................................................................................................................... 212 9.2.6 Engineering access and maintenance.............................................................................................................. 212 9.2.7 Example installation........................................................................................................................................ 213 9.3 Communications Channels..................................................................................................................................... 213 9.3.1 Channel capacity ............................................................................................................................................. 213 9.3.2 Channel reliability........................................................................................................................................... 214 9.3.3 Channel availability ........................................................................................................................................ 214 9.3.4 Propagation delay............................................................................................................................................ 214 9.4 Fiber-Optic-Based Communication ....................................................................................................................... 214 9.4.1 Optical fiber types and characteristics ............................................................................................................ 215 9.4.2 Fiber-optic connectors and transceivers.......................................................................................................... 215
xii
9.4.3 Dedicated fiber-optic channels ........................................................................................................................216 9.4.3.1 SEL fiber-optic transceivers for 0­115 kbps applications .......................................................................217 9.4.3.2 Fiber-optic-based remote I/O modules.....................................................................................................218 9.4.3.3 Fiber-optic-based temperature measurement module ..............................................................................219 9.4.4 Shared fiber-optic channels .............................................................................................................................219 9.4.4.1 Fiber-optic multiplexers ...........................................................................................................................219 9.4.4.2 SEL support for direct fiber-optic interface to multiplexers ....................................................................220 9.4.4.3 SONET .....................................................................................................................................................221 9.4.4.4 Native Ethernet transport .........................................................................................................................221 9.4.4.5 Comparison between native Ethernet and SONET ..................................................................................222 9.4.4.6 SEL Integrated Communications Optical Network .................................................................................222 9.5 Wireless Systems ....................................................................................................................................................223 9.5.1 Microwave.......................................................................................................................................................223 9.5.2 Narrow-band VHF/UHF radio ........................................................................................................................223 9.5.3 Spread-spectrum radio.....................................................................................................................................224 9.6 Modern Communication-Based Protection ............................................................................................................224 9.6.1 Communication-based protection schemes .....................................................................................................225 9.6.2 Improving the reliability of communication-based protection........................................................................226 9.6.3 Communications standards..............................................................................................................................226 9.6.4 Environmental and performance standards .....................................................................................................226 9.7 MIRRORED BITS Communications..........................................................................................................................226 9.7.1 Description ......................................................................................................................................................226 9.7.2 Security............................................................................................................................................................227 9.7.3 Dependability ..................................................................................................................................................227 9.7.4 Channel performance monitoring....................................................................................................................227 9.7.5 Implementation example .................................................................................................................................228 9.7.6 Logic processor ...............................................................................................................................................228 9.7.7 MIRRORED BITS tester .....................................................................................................................................229 9.8 Ethernet Communication ........................................................................................................................................229 9.8.1 Ethernet port speed and fiber-optic interface ..................................................................................................229 9.8.2 Full-duplex operation and collision-free environment ....................................................................................229 9.8.3 IEEE 802.3x flow control................................................................................................................................230 9.8.4 Priority queuing and VLAN support ...............................................................................................................230 9.8.5 Loss-of-link management................................................................................................................................230 9.8.6 Remote monitoring, port mirroring, and diagnostics ......................................................................................231 9.8.7 LAN-based network protocols ........................................................................................................................231 9.8.8 Ethernet-based protection message standards .................................................................................................231 9.8.9 Ethernet-based SEL product portfolio.............................................................................................................231 9.8.10 Ethernet radio ..................................................................................................................................................232 9.9 Future Trends..........................................................................................................................................................233 9.10 References...............................................................................................................................................................234
10 Information Processing ............................................................................................................................................237
10.1 Introduction.............................................................................................................................................................237 10.2 Operations Technology and information technology............................................................................................237 10.3 Integrated IED Networks........................................................................................................................................239 10.3.1 Communication makes IEDs informed and organized....................................................................................239
10.3.2 hierarchical levels of integrated IED networks ..............................................................................................240
10.3.2.1 Process level.............................................................................................................................................240
10.3.2.2 Unit level ..................................................................................................................................................240
10.3.2.3 Station level..............................................................................................................................................240
10.3.2.4 Enterprise level.........................................................................................................................................240
10.3.3 10.3.4 10.3.5 10.3.6
Serial networks and Ethernet local-area networks ..........................................................................................240 Star, multidrop, and ring LAN configurations ................................................................................................241 SEL Best Practice Methods support serial and Ethernet LANs ......................................................................242 SEL Best Practice Methods for protection, control, and monitoring networks...............................................245
10.4 SEL Specialized IEDs Improve Data Processing ...................................................................................................245 10.4.1 Categories of power system data.....................................................................................................................245
10.4.2 SEL IEDs provide specialized processing.......................................................................................................246
xiii 10.4.3 SEL IED communication surpasses communication focused only on SCADA............................................. 247 10.4.4 SEL IEDs create situational awareness........................................................................................................... 248 10.4.5 SEL IEDs create apparatus data models ......................................................................................................... 248 10.4.6 Migration to routable protocols reduces security and increases complexity .................................................. 249 10.4.6.1 Message payload transparency ................................................................................................................ 249 10.4.6.2 SEL protocols are purpose-built .............................................................................................................. 250 10.4.6.3 Routing the nonroutable........................................................................................................................... 250 10.4.6.4 Protecting transparent data and routable messages.................................................................................. 250 10.4.6.5 Routing improves performance ............................................................................................................... 250 10.4.6.6 SEL protocols provide optimal blend ...................................................................................................... 251 10.5 SEL Increases LAN Functionality ......................................................................................................................... 252 10.5.1 SEL Best Practices based on scientific measures ........................................................................................... 252 10.5.2 Different networks require different information processors ......................................................................... 252 10.5.3 Data processing ............................................................................................................................................... 253 10.5.4 Automation functions...................................................................................................................................... 254 10.5.5 Network functions........................................................................................................................................... 254 10.5.6 Information notification and visualization...................................................................................................... 255 10.5.7 Other SEL advantages..................................................................................................................................... 255 10.6 Create Best-in-Class Networks .............................................................................................................................. 255 10.6.1 Modern communications methods satisfy IED network tasks........................................................................ 255 10.6.2 SEL ICON provides for new generation networks ......................................................................................... 257 10.7 Use IEC Standard 61850 Network Evaluation Methods........................................................................................ 258 10.7.1 SEL designs for availability............................................................................................................................ 258 10.7.2 SEL designs for performance.......................................................................................................................... 258 10.8 SEL IEDs Monitor, Decide, and Act...................................................................................................................... 259 10.8.1 Separate protection and automation................................................................................................................ 259 10.8.2 Automate with networked SEL IEDs.............................................................................................................. 260 10.8.3 SEL versatility................................................................................................................................................. 261 10.9 References .............................................................................................................................................................. 261 11 information security .................................................................................................................................................. 263 11.1 Introduction ............................................................................................................................................................ 263 11.2 Important Security Tips.......................................................................................................................................... 263 11.3 Attacker Profile and Motivation............................................................................................................................. 264 11.3.1 Advantages of electronic attack methods........................................................................................................ 264 11.3.2 Groups that threaten the electric power infrastructure.................................................................................... 264 11.3.2.1 Government-sponsored information warfare programs........................................................................... 264 11.3.2.2 Hostile organizations ............................................................................................................................... 264 11.3.2.3 Insiders..................................................................................................................................................... 265 11.3.2.4 Hackers .................................................................................................................................................... 265 11.4 Attack Techniques and Tools................................................................................................................................. 265 11.4.1 Network reconnaissance ................................................................................................................................. 265 11.4.2 Active scanning............................................................................................................................................... 266 11.4.3 Exploiting vulnerabilities................................................................................................................................ 267 11.4.3.1 Exploiting SCADA network vulnerabilities ............................................................................................ 267 11.4.3.2 Exploiting vulnerable user-login services................................................................................................ 268 11.4.3.3 Exploiting vulnerable software or system users ...................................................................................... 269 11.4.4 Attack propagation.......................................................................................................................................... 270 11.5 Prioritizing Electronic Security Risks in the Electric Power Industry ................................................................... 270 11.6 Defensive Technologies and Strategies.................................................................................................................. 271 11.6.1 Electronic attack barriers ................................................................................................................................ 271 11.6.2 Defining the electronic security perimeter...................................................................................................... 272 11.6.3 Limiting access to protected networks............................................................................................................ 272 11.6.3.1 Choosing secure communications technologies ...................................................................................... 272 11.6.3.2 Implementing restrictive traffic filtering to isolate critical TCP/IP LAN segments................................ 272 11.6.3.3 Using security settings in communications gateways to manage channel availability............................ 273 11.6.4 Implementing strong cryptographic link security ........................................................................................... 273
xiv 11.6.5 Implementing strong, local electronic access controls in critical devices.......................................................275 11.6.5.1 Strong passwords......................................................................................................................................276 11.6.5.2 Password-based access control.................................................................................................................276 11.6.5.3 Cryptographic access controls..................................................................................................................277 11.6.6 Securing personal computers...........................................................................................................................277 11.7 Detecting and Responding to Electronic Attacks ...................................................................................................277 11.8 References...............................................................................................................................................................279 12 Protection System Reliability and Testing .......................................................................................................281 12.1 Introduction.............................................................................................................................................................281 12.2 Reliability Concepts................................................................................................................................................281 12.2.1 Definitions and measures ................................................................................................................................281 12.2.2 Failure rates and patterns of failure .................................................................................................................282 12.3 System reliability analysis Methods.....................................................................................................................282 12.3.1 Block diagram method ....................................................................................................................................282 12.3.2 Fault-tree analysis method...............................................................................................................................283 12.3.2.1 Device failure rates and unavailabilities ..................................................................................................283 12.3.2.2 Fault-tree construction..............................................................................................................................283 12.3.2.3 Advantages of fault-tree analysis .............................................................................................................284 12.4 Improving Availability ...........................................................................................................................................285 12.4.1 Redundant protection systems.........................................................................................................................285 12.4.2 Design Considerations for redundant protection systems ................................................................................285 12.4.3 Aviation industry comparison .........................................................................................................................286 12.4.4 Advantages of redundant protection configurations........................................................................................286 12.4.5 Effect of common-mode failures.....................................................................................................................287 12.5 Selecting Reliable Protective Relays ......................................................................................................................287 12.5.1 Designing products for quality and reliability.................................................................................................287 12.5.1.1 Designing for simplicity...........................................................................................................................287 12.5.1.2 Selecting reliable components..................................................................................................................288 12.5.1.3 Analyzing designs for reliability ..............................................................................................................288 12.5.2 Thoroughly testing products before release ....................................................................................................288 12.5.2.1 Real-time digital simulation testing .........................................................................................................288 12.5.2.2 Highly accelerated life test extends operating margin .............................................................................289 12.5.2.3 Type testing beyond standard requirements extends performance margin ..............................................289 12.5.2.4 Reliability test ..........................................................................................................................................289 12.5.3 Manufacturing for reliability ...........................................................................................................................290 12.5.4 Using field data to increase product reliability................................................................................................290 12.6 Relay Testing and Commissioning.........................................................................................................................291 12.6.1 Microprocessor-based relay self-tests .............................................................................................................291 12.6.2 Additional microprocessor-based relay monitoring features ..........................................................................292 12.6.2.1 Loss-of-potential or loss-of-current detection features act as self-tests...................................................292 12.6.2.2 Metering ...................................................................................................................................................292 12.6.2.3 Relay event data analysis detects problems .............................................................................................292 12.6.2.4 Exercising output contacts .......................................................................................................................293 12.6.3 Testing microprocessor-based relays ..............................................................................................................293 12.6.3.1 Type testing ..............................................................................................................................................293 12.6.3.2 Commissioning testing.............................................................................................................................293 12.6.3.3 Routine maintenance testing ....................................................................................................................294 12.6.3.4 Automated event retrieval ........................................................................................................................294 12.7 References...............................................................................................................................................................294 13 Substation Protection, Control, and monitoring system Design.............................................................297 13.1 Introduction.............................................................................................................................................................297 13.2 Design Objectives of Substation Protection, Control, and Monitoring Systems....................................................297 13.2.1 functional requirements ..................................................................................................................................297 13.2.2 Design objectives.............................................................................................................................................297 13.2.3 Benefits of system integration and automation ...............................................................................................298
xv 13.3 DC Control Power System Requirements for Substations..................................................................................... 298 13.3.1 Battery monitoring features built into SEL relays .......................................................................................... 298 13.3.2 External battery monitoring systems............................................................................................................... 299 13.4 Protection System Redundancy.............................................................................................................................. 299 13.5 DC Logic Circuit Design........................................................................................................................................ 300 13.5.1 Circuit layout................................................................................................................................................... 300 13.5.2 DC system fault protection ............................................................................................................................. 301 13.5.3 Tripping/closing circuit design ....................................................................................................................... 302 13.5.3.1 Programmable logic simplifies the dc control circuits ............................................................................ 302 13.5.3.2 DC circuit monitoring .............................................................................................................................. 304 13.5.3.3 Communications system monitoring ....................................................................................................... 304 13.5.4 Auxiliary relays............................................................................................................................................... 305 13.5.4.1 Direct tripping.......................................................................................................................................... 305 13.5.4.2 Close interlocking .................................................................................................................................... 306 13.5.4.3 Seal-in auxiliary relay function................................................................................................................ 306 13.5.4.4 Switching inductive dc circuits................................................................................................................ 306 13.5.5 Remote I/O modules ....................................................................................................................................... 306 13.5.6 Targeting considerations ................................................................................................................................. 307 13.5.7 Manual control system design......................................................................................................................... 309 13.5.7.1 Manual control system redundancy ......................................................................................................... 309 13.5.7.2 Independent control pushbuttons ............................................................................................................. 310 13.5.7.3 Control signal communications paths...................................................................................................... 311 13.5.7.4 Large operator controls provide redundancy for substation computer .................................................... 311 13.5.8 Using communications links for critical protection and control functions..................................................... 311 13.6 AC Sensing Circuit Design .................................................................................................................................... 313 13.6.1 Circuit design .................................................................................................................................................. 313 13.6.2 Power system protection circuits .................................................................................................................... 313 13.6.3 Metering circuits ............................................................................................................................................. 313 13.6.4 Transient recording ......................................................................................................................................... 314 13.6.5 Continuous monitoring of device measurements............................................................................................ 314 13.7 Application of Test Switches ................................................................................................................................. 314 13.8 Design Documentation........................................................................................................................................... 314 13.8.1 Complete design documentation package....................................................................................................... 315 13.8.2 DC elementary (schematic) diagrams ............................................................................................................. 315 13.8.3 Logic diagrams................................................................................................................................................ 316 13.8.4 Standards......................................................................................................................................................... 317 13.9 Panel and Substation Control Enclosure Design.................................................................................................... 317 13.9.1 Purpose of a substation control enclosure....................................................................................................... 317 13.9.2 Protection, control, and monitoring panel design ........................................................................................... 318 13.9.3 Effects of integrated protection, control, and monitoring systems on enclosure design ................................ 319 13.9.4 Substation control enclosure environmental system ....................................................................................... 320 13.9.5 Eliminating the centralized control enclosure................................................................................................. 321 13.10 References .............................................................................................................................................................. 322 14 Using Power System Information ........................................................................................................................ 323 14.1 Introduction ............................................................................................................................................................ 323 14.2 Asset Management ................................................................................................................................................. 323 14.3 SEL Multifunction Relays: A Wealth of Information............................................................................................ 324 14.4 Upgrading Protection, Control, and Monitoring Equipment.................................................................................. 325 14.5 Upgrading a Substation Using SEL Multifunction Relays .................................................................................... 326 14.5.1 Integrated system architecture ........................................................................................................................ 326 14.5.2 System functionality ....................................................................................................................................... 327 14.5.2.1 Protection ................................................................................................................................................. 327 14.5.2.2 Control ..................................................................................................................................................... 327 14.5.2.3 Metering................................................................................................................................................... 328 14.5.2.4 SCADA functionality .............................................................................................................................. 328 14.5.2.5 Fault recording......................................................................................................................................... 328 14.5.2.6 Sequential events recording ..................................................................................................................... 328 14.5.2.7 Blocking................................................................................................................................................... 328
xvi 14.5.2.8 Tagging.....................................................................................................................................................328 14.5.2.9 Transformer monitoring ...........................................................................................................................328 14.5.2.10 Breaker monitoring..................................................................................................................................328 14.5.2.11 Battery monitoring...................................................................................................................................328 14.5.2.12 Substation control enclosure and weather monitoring.............................................................................328 14.5.2.13 Information display system......................................................................................................................329 14.5.3 Substation control enclosure............................................................................................................................329 14.5.4 Additional cost considerations ........................................................................................................................329 14.6 Data Monitoring and Analysis Improve Asset Management .................................................................................330 14.6.1 Data flow .........................................................................................................................................................330 14.6.2 Transformer monitoring ..................................................................................................................................330 14.6.2.1 Thermal monitoring..................................................................................................................................331 14.6.2.2 Loss-of-life monitoring ............................................................................................................................331 14.6.2.3 Through-fault monitoring.........................................................................................................................331 14.6.2.4 Phase current monitoring .........................................................................................................................331 14.6.2.5 Cooling fan monitoring ............................................................................................................................331 14.6.3 Breaker monitoring..........................................................................................................................................332 14.6.4 Capacitor bank monitoring ..............................................................................................................................333 14.6.5 Battery monitoring...........................................................................................................................................333 14.6.6 Synchroscope for autosynchronizer ................................................................................................................333 14.6.7 Substation control enclosure and weather monitoring ....................................................................................333 14.6.8 Applications.....................................................................................................................................................334 14.7 References...............................................................................................................................................................334 Index........................................................................................................................................................................................337 Biographies...........................................................................................................................................................................359
List of Figures
Figure 1.1 Figure 1.2 Figure 1.3 Figure 1.4 Figure 1.5 Figure 1.6 Figure 1.7 Figure 1.8 Figure 1.9 Figure 1.10 Figure 1.11 Figure 2.1 Figure 2.2 Figure 2.3 Figure 2.4 Figure 2.5 Figure 2.6 Figure 2.7 Figure 2.8 Figure 2.9 Figure 2.10 Figure 2.11 Figure 2.12 Figure 2.13 Figure 2.14 Figure 2.15 Figure 2.16 Figure 2.17 Figure 2.18 Figure 2.19 Figure 2.20
(a) The Global Positioning System provides an accurate and globally available reference for timesynchronized measurements (picture courtesy of U.S. Department of Defense). (b) Terrestrial networks using the SEL ICON also provide an accurate time reference over a wide area.............................................. 2 Recloser mounted on a distribution pole. Modern recloser controls provide protection, control, and monitoring functions that meet the requirements of today's distribution systems........................................... 2 Transmission systems have evolved from regional networks to interconnected power grids covering large geographical areas. ........................................................................................................................................... 3 Modern solutions for transformer protection and monitoring prevent costly failures and extend transformer life..................................................................................................................................................................... 4 Buses can have complex configurations. Modern relays monitoring the bus and breakers provide fast and secure bus and breaker-failure protection......................................................................................................... 4 New generation sources require better generator protection, control, and monitoring. These distributed, intermittent sources also challenge transmission and distribution system protection and control................... 5 Wide-area protection, control, and monitoring systems reduce the risk of major blackouts in modern power systems, which operate close to their security limits. ...................................................................................... 5 The number of electronic vulnerabilities reported worldwide has increased dramatically. Modern techniques allow us to provide cybersecurity in depth. This figure was created by Schweitzer Engineering Laboratories, Inc., using information from [1]. ........................................................................... 6 Power system reliability is critically important to daily life, so protection systems must perform correctly to preserve system integrity during all types of conditions............................................................... 7 Modern technology provides low-cost, complete solutions for power system protection, control, and monitoring. ....................................................................................................................................................... 7 Modern relays provide a wealth of information for asset management in electric utilities and industrial companies......................................................................................................................................................... 7 Synchrophasors associate phasor measurements to an absolute time reference across the power system.......... 9 SEL satellite-synchronized clocks. .................................................................................................................... 10 Preferred high-accuracy IRIG-B time distribution methods. (a) Clock with single high-accuracy IRIG-B output. (b) Clock with multiple high-accuracy IRIG-B outputs. ................................................................... 11 Using a communications processor in a substation IRIG-B signal distribution system. ................................... 11 Time-distribution hierarchy using the IEEE Standard 1588 implemented on Ethernet switches...................... 12 Synchrophasor representation using the UTC reference. .................................................................................. 12 Voltages at different network locations.............................................................................................................. 13 Phasor angle measurements at two locations at off-nominal frequency. .......................................................... 13 Active and reactive power transfer depends on the magnitudes and angles of the system voltages.................. 13 Architecture of a device that combines time-synchronized measurements with PCM functions...................... 15 Measured, actual, and error phasors. The circle encompasses all possible phasor measurements for a specified TVE value........................................................................................................................................ 15 Power system model, synchrophasor data acquisition system, and visualization applications. ........................ 16 Three-source RTDS power system model with four SEL-421 relays acting as PMCUs for synchrophasor measurement and protection........................................................................................................................... 16 SEL-5078 SYNCHROWAVE Console Software screens showing the angle and frequency difference between Bus 1 and Bus 4 for prefault and post-fault conditions. The system oscillations damp out after load shedding. ........................................................................................................................................................ 17 Synchrophasor data (positive-sequence impedance and voltage magnitude) measured by PMCU 3 for a three-phase fault on Line 3. No synchrophasor data were lost during the fault condition............................. 18 Angle difference between voltages at Bus 3 and Bus 4 calculated from the synchrophasor data measured by PMCU 3 and PMCU 4. ............................................................................................................................. 18 SYNCHROWAVE Console visualization showing positive-sequence impedance magnitudes calculated by PMCU 3 from protection and synchrophasor data......................................................................................... 18 Two-source RTDS power system model with two SEL-421 relays acting as PMCUs for synchrophasor measurement................................................................................................................................................... 19 Comparison of Bus 1 to Bus 2 angle difference measured by PMCUs and calculated by RTDS for a 200 ms three-phase fault. ............................................................................................................................... 19 Comparison of Bus 1 to Bus 2 angle difference measured by PMCUs and calculated by RTDS for a 250 ms three-phase fault. ............................................................................................................................... 19
xviii
Figure 2.21 Figure 2.22 Figure 2.23 Figure 2.24 Figure 2.25 Figure 2.26 Figure 2.27 Figure 2.28 Figure 2.29 Figure 2.30 Figure 2.31 Figure 2.32 Figure 2.33 Figure 3.1 Figure 3.2 Figure 3.3 Figure 3.4 Figure 3.5 Figure 3.6 Figure 3.7 Figure 3.8 Figure 3.9 Figure 3.10 Figure 3.11 Figure 3.12 Figure 3.13 Figure 3.14 Figure 3.15 Figure 3.16 Figure 3.17 Figure 3.18 Figure 3.19 Figure 3.20 Figure 3.21 Figure 3.22 Figure 3.23 Figure 3.24 Figure 3.25 Figure 3.26 Figure 3.27 Figure 3.28 Figure 3.29 Figure 3.30 Figure 3.31 Figure 3.32 Figure 3.33
SEL-3306 Synchrophasor Processor and SEL-3373 Station PDC.....................................................................20 SEL-3378 Synchrophasor Vector Processor and SEL-3530 Real-Time Automation Controller. ......................20 SEL-3378 functionality. .....................................................................................................................................21 SEL devices with time-synchronized measurement ability................................................................................23 Combining time-aligned data from different locations in one oscillogram simplifies fault analysis (courtesy of B. D. Eisenbarth, Nebraska Public Power District)....................................................................24 Time-aligned event report obtained using the EVE P command. ......................................................................24 Time-synchronized reports obtained from two SEL-421 relays at different locations. .....................................24 Synchrophasor system using a real-time synchrophasor processor. ..................................................................24 Using one synchrophasor processor in a local system. ......................................................................................25 Using several synchrophasor processors in a wide-area system. .......................................................................25 Example of SEL synchrophasor system using different communications channels. .........................................25 SCADA application of synchrophasors. ............................................................................................................26 SEL SYNCHROWAVE Console synchrophasor screen.........................................................................................27 Overcurrent protection is time-delayed to provide coordination. ......................................................................30 Functional diagram of the SEL-351S Protection System...................................................................................31 Microprocessor-based multifunction recloser controls. (a) SEL-351R Recloser Control. (b) SEL-651R Advanced Recloser Control. ...........................................................................................................................31 SEL protection, control, and metering panel for three feeders. Three SEL-351 relays replace nine phase relays, three ground relays, three reclosing relays, and many auxiliary relays. .............................................32 SEL-501 Dual Universal Overcurrent Relay provides two sets of overcurrent, breaker-failure, and motor protection functions. .......................................................................................................................................32 Negative-sequence elements benefit feeder, bus, and backup protection...........................................................33 Negative-sequence overcurrent element.............................................................................................................33 Negative-sequence overcurrent elements easily coordinate with devices that respond to phase currents. ........33 Defining an equivalent phase element, you can use the normal coordination procedure for negative- sequence overcurrent elements. ......................................................................................................................34 Coordination between a negative-sequence overcurrent element and the phase overcurrent element of a downstream recloser. ......................................................................................................................................34 Coordination between a negative-sequence overcurrent element and a downstream 100T fuse (courtesy of BC Hydro). .................................................................................................................................34 The SEL positive-sequence, voltage-polarized directional element (32P) provides directional discrimination for three-phase faults. .............................................................................................................35 Negative-sequence network for a ground fault at the end of the protected line in a two-source system. ..........37 Operating characteristics of the SEL 32Q and 32V directional elements..........................................................37 Zero-sequence network for a forward ground fault in an ungrounded system. .................................................38 The SEL zero-sequence, voltage-polarized directional element for ungrounded systems (32U) provides sensitive and selective ground fault detection.................................................................................................38 Single-line diagram and zero-sequence network of a resonant-grounded distribution system. .........................39 SEL wattmetric directional element (32W) provides sensitive and selective ground fault detection in resonant-grounded systems.............................................................................................................................39 Zero-sequence network for a forward ground fault in a resistance-grounded system. ......................................40 Application of a zero-sequence, voltage-polarized directional element (32V) to a high-resistance grounded system. ............................................................................................................................................................41 A high-impedance fault detection system that uses the total nonharmonic content of phase currents to detect arcing activity. ......................................................................................................................................41 High load current makes traditional bus phase overcurrent elements ineffective as feeder relay backup protection. .......................................................................................................................................................42 Cold-load restoration scheme improves sensitivity by temporarily changing the pickup current of phase and ground overcurrent elements without modifying their time-current curve..............................................43 Traditional local-area islanding detection uses voltage and frequency variations as indicators of islanding. ...44 SEL local-area islanding detection element. ......................................................................................................44 Power system model to analyze the performance of islanding detection schemes. ...........................................44 SEL islanding detection scheme is faster than traditional schemes. ..................................................................44 direct transfer trip over a communications channel provides islanding detection when DG active power generation matches the local-area load...........................................................................................................45 SEL-351 relays protect a wind farm. Multifunction SEL relays provide comprehensive interconnection protection for DG installations. ......................................................................................................................46 SEL-751A with a point sensor connected to the arc-flash card. ........................................................................48 Inverse-time characteristic of the SEL-751A arc-flash TOL elements. .............................................................48 SEL-751A fault event report containing current and light data. ........................................................................49 Switchgear application example.........................................................................................................................49
xix
Figure 3.34 Figure 3.35 Figure 3.36 Figure 3.37 Figure 3.38 Figure 3.39 Figure 3.40 Figure 3.41 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 4.9 Figure 4.10 Figure 4.11 Figure 4.12 Figure 4.13 Figure 4.14 Figure 4.15 Figure 4.16 Figure 4.17 Figure 4.18 Figure 4.19 Figure 4.20 Figure 4.21 Figure 4.22 Figure 4.23 Figure 4.24 Figure 4.25 Figure 4.26 Figure 4.27 Figure 4.28 Figure 4.29 Figure 4.30 Figure 4.31 Figure 4.32 Figure 4.33 Figure 4.34 Figure 4.35 Figure 4.36 Figure 4.37 Figure 4.38 Figure 4.39 Figure 4.40 Figure 4.41 Figure 4.42 Figure 4.43
Automatic throw-over scheme using SEL-351R Recloser Controls and MIRRORED BITS communications. ... 50 Elementary diagram of a network reconfiguration scheme using SEL-651R Advanced Recloser Controls and MIRRORED BITS communications............................................................................................. 51 In a centralized distribution automation system, a DAC coordinates the control logic and communication among the IEDs.............................................................................................................................................. 52 International Drive system single-line diagram. ................................................................................................ 52 Overhead AutoRANGER FCIs automatically adjust to varying load conditions.............................................. 53 Test point FCIs are an economical, durable solution......................................................................................... 53 The RadioRANGER Wireless Fault Indication System communicates FCI status from phase sensors in an underground vault to a handheld remote fault reader..................................................................................... 53 Remote displays provide indication from the outside of a pad-mounted transformer, switchgear, and other enclosures to facilitate quick, easy fault locating........................................................................................... 54 The power system of NORTH AMERICA includes several large ac transmission systems interconnected through asynchronous (dc) links. ................................................................................................................... 58 In modern power systems, contingency studies may not include all possible real-life events. ......................... 58 Directional overcurrent protection application in a two-source power system.................................................. 61 Impedance-plane representation of distance element operation. ....................................................................... 61 Distance protection application in a two-source power system......................................................................... 62 provides information on the location of the fault with respect to the relay reach point. .................................. 64 Mho element characteristic derivation............................................................................................................... 64 Mho element characteristics. (a) Self-polarized mho element. (b) Polarized mho element responding to a forward fault. (c) Polarized mho element responding to a reverse fault. ....................................................... 65 Shaping a quadrilateral distance characteristic requires reactance, resistance, and directional elements. ........ 66 Reactance element characteristic derivation. ..................................................................................................... 66 The characteristic of a reactance element polarized with I 2 or I 0 adapts to the tilt that power flow causes in the apparent fault impedance. ......................................................................................................... 67 Adaptive resistance element characteristic. ....................................................................................................... 68 Distance calculation of a phase mho element with long polarizing memory during a frequency excursion..... 69 A mho element with long polarizing memory can misoperate during frequency excursions. (a) Disturbance starts. (b) V P MEM moves into the operating region. ........................................................... 70 Adaptive polarizing scheme............................................................................................................................... 70 Distance calculation of a phase mho element with adaptive polarizing memory. ............................................. 70 Zone 1 mho element using dual-filter scheme................................................................................................... 71 The SEL-421 Protection, Automation, and Control System provides high-speed line protection, advanced control and monitoring functions, and synchrophasor measurements. .......................................................... 71 Half- and one-cycle combined logic for the A-phase-to-ground fault loop....................................................... 72 Half-cycle and one-cycle signals for an A-phase-to-ground fault. .................................................................... 72 Infeed effect causes impedance Measurement errors......................................................................................... 72 For resistive faults, relays at both line ends measure only a portion of the current flowing through the fault resistance. ....................................................................................................................................................... 73 Fault resistance causes distance element measurement errors........................................................................... 74 Complex voltage plane representation of a resistive fault in a nonhomogeneous system. ................................ 74 Zero-sequence network for a ground fault in the system shown in Figure 4.22................................................ 75 Mutual coupling affects ground distance and directional elements................................................................... 75 Load-encroachment element characteristic. ...................................................................................................... 76 Power system model. ......................................................................................................................................... 76 Measured impedances for an AG fault. ............................................................................................................. 77 Measured impedances for a BCG fault.............................................................................................................. 77 CCVTs with passive FSCs have better transient response than CCVTs with active FSCs. .............................. 78 CCVT blocking logic output for CCVT transient with SIR = 10. ..................................................................... 78 LOP algorithm overview. ................................................................................................................................... 79 Direct underreaching transfer trip logic............................................................................................................. 79 Permissive underreaching transfer trip logic. .................................................................................................... 80 Permissive overreaching transfer trip logic........................................................................................................ 80 Directional comparison blocking logic.............................................................................................................. 80 Fault-resistance coverage regions of directional comparison schemes in an example two-source system [24]. .................................................................................................................................................... 81 Hybrid directional comparison logic. ................................................................................................................ 83 Current-only pilot schemes compare current information from all the line terminals. ..................................... 84 Alpha-plane representation of power system load and fault conditions. ........................................................... 85 Effect of channel-delay compensation errors. ................................................................................................... 85 Alpha-plane differential element characteristic. ................................................................................................ 86
xx
Figure 4.44 Figure 4.45 Figure 4.46 Figure 4.47 Figure 4.48 Figure 4.49 Figure 4.50 Figure 4.51 Figure 4.52 Figure 4.53 Figure 4.54 Figure 4.55 Figure 4.56 Figure 4.57 Figure 4.58 Figure 4.59 Figure 5.1 Figure 5.2 Figure 5.3 Figure 5.4 Figure 5.5 Figure 5.6 Figure 5.7 Figure 5.8 Figure 5.9 Figure 5.10 Figure 5.11 Figure 5.12 Figure 5.13 Figure 5.14 Figure 5.15 Figure 5.16 Figure 5.17 Figure 5.18 Figure 5.19 Figure 5.20 Figure 5.21 Figure 5.22 Figure 5.23 Figure 5.24 Figure 5.25 Figure 5.26 Figure 5.27 Figure 5.28 Figure 5.29 Figure 5.30 Figure 5.31
The alpha-plane differential element is more sensitive and more tolerant of channel asymmetry than percentage differential elements. ....................................................................................................................86 The alpha-plane differential element is more sensitive and more tolerant of CT saturation than percentage differential elements. ......................................................................................................................................87 Effect of using restraining currents and external fault detection logic in the generalized alpha-plane differential element for CT saturation conditions...........................................................................................88 The SEL-311L Line Current Differential System combines line differential and directional comparison protection. .......................................................................................................................................................90 Logic and time diagrams of a half-wave phase comparison protection scheme. ...............................................91 Fault-resistance coverage of SEL-311L negative- and zero-sequence differential elements.............................92 Voltage inversion may affect the directional discrimination of the faulted line and adjacent line relays. .........94 In series-compensated lines, distance elements may overreach because of the impedance oscillation caused by the subharmonic-frequency transient.............................................................................................95 The SEL-421 relay series-compensation algorithm blocks the Zone 1 element when the fault is beyond the series capacitor................................................................................................................................................95 The measured voltage, the calculated voltage, and their ratio vary as the fault location moves along the series-compensated line. .................................................................................................................................96 Positive-sequence voltage is a reliable polarizing quantity for mho elements used in SPT schemes................97 Simultaneous faults on two parallel lines...........................................................................................................98 Power swings may cause undesirable distance element operation.....................................................................99 SEL relays use a power swing detection characteristic composed of two concentric polygons........................99 Phasor diagram of a two-source power system. ...............................................................................................100 Negative-sequence network for an unbalanced fault in the system shown in Figure 4.22...............................104 Typical differential element connection diagram. ............................................................................................108 Percentage differential element single- and dual-slope operating characteristics............................................109 Adaptive differential element characteristic.....................................................................................................109 DABY or Dy1 transformer connection. ...........................................................................................................110 YDAC or Yd1 transformer connection. ...........................................................................................................110 Microprocessor-based transformer relays allow connecting CTs in wye. .......................................................111 Microprocessor-based transformer relays perform current scaling, phase-shift compensation, and zero- sequence current removal. ............................................................................................................................111 DAB-connection compensation. ......................................................................................................................111 Zero-sequence current flows only on the wye side of a delta-wye transformer for external ground faults.....112 A grounding bank within the differential protection zone requires removing the zero-sequence current. ......112 Exciting current of an overexcited transformer. ...............................................................................................113 Response of a C100, 600/5 CT to a 12,000 A fault current with dc offset. .....................................................114 The SEL-387 Current Differential and Overcurrent Relay provides protection, control, and monitoring functions for transformers and autotransformers..........................................................................................115 Differential element blocking based on determining the dc content of the differential current. (a) Inrush current. (b) Internal fault current. .................................................................................................................116 Even-harmonic restrained 87R1 and unrestrained 87U1 differential elements................................................117 DC-ratio blocking logic....................................................................................................................................117 Differential-element blocking logic. ................................................................................................................117 Differential relay common harmonic blocking logic. ......................................................................................117 Adaptive differential element runs harmonic restraint and blocking in parallel. .............................................118 Schematic diagram of the SEL-487E Transformer Differential Protection Relay. ..........................................119 Negative-sequence differential element. ..........................................................................................................120 Transformer neutral current magnitude is higher than phase current magnitude for ground faults close to the transformer neutral..............................................................................................................................121 REF protection for two-winding transformers using a current-polarized directional element. .......................121 REF protection for an autotransformer with two breakers on the high-voltage side. ......................................122 Typical transformer overcurrent relay protection scheme................................................................................124 Combined transformer and bus protection. (a) One relay provides a combined protection zone. (b) Two relays provide separate bus and transformer zones.........................................................................126 An SEL-487E relay provides transformer differential protection, fast bus tripping, and protection for up to three radial feeders....................................................................................................................................126 Screen capture of a transformer-monitoring HMI module using microprocessor-based relays to monitor transformer loading and temperatures, and to estimate loss-of-life data......................................................128 The transformer thermal model uses the ambient temperature to calculate other temperatures......................128 Section of the through-fault capability curve for a 100 MVA, Category IV transformer with ZT = 0.07 p.u..131 Transformer through-fault monitoring and alarm logic. ..................................................................................131
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Figure 5.32 Figure 6.1 Figure 6.2 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Figure 6.8 Figure 6.9 Figure 6.10 Figure 6.11 Figure 6.12 Figure 6.13 Figure 6.14 Figure 6.15 Figure 6.16 Figure 6.17 Figure 6.18 Figure 6.19 Figure 6.20 Figure 6.21 Figure 6.22 Figure 6.23 Figure 6.24 Figure 6.25 Figure 6.26 Figure 6.27 Figure 6.28 Figure 6.29 Figure 6.30 Figure 6.31 Figure 6.32 Figure 6.33 Figure 6.34 Figure 6.35 Figure 7.1 Figure 7.2 Figure 7.3 Figure 7.4 Figure 7.5 Figure 7.6 Figure 7.7 Figure 7.8 Figure 7.9 Figure 7.10 Figure 7.11 Figure 7.12
Overheating of insulation components and severe through faults reduce transformer stress-withstand capability. ..................................................................................................................................................... 132 Bus differential overcurrent protection scheme. .............................................................................................. 137 Equivalent circuit of the differential overcurrent scheme when the CT of the faulted branch circuit is fully saturated. ...................................................................................................................................................... 137 SEL-587Z High-Impedance Differential Relay. .............................................................................................. 138 Bus high-impedance differential protection scheme........................................................................................ 139 Cutaway of SEL-587Z High-Impedance Differential Relay............................................................................ 139 Summing junction voltage for a 40 kA asymmetrical internal fault in a high-impedance differential scheme with C200, 1200:5 CTs. .................................................................................................................. 140 Bus percentage differential protection scheme. ............................................................................................... 141 Using SEL-487B relays to protect buses with as many as 18 terminals.......................................................... 141 The SEL-487B Bus Differential and Breaker-Failure Relay. .......................................................................... 142 Block diagram showing the logic for Bus Protection Zone 1.......................................................................... 143 Advanced differential element response to an internal fault with CT saturation............................................. 144 Advanced differential element response to an external fault with severe CT saturation. ................................ 144 Bus partial differential protection scheme. ...................................................................................................... 144 Zone-interlocked, directional comparison bus protection application............................................................. 145 Zone-interlocked, directional comparison scheme logic. ................................................................................ 145 Fast bus-tripping scheme application............................................................................................................... 147 Fast bus-tripping scheme logic. ....................................................................................................................... 147 Basic breaker-failure protection scheme.......................................................................................................... 149 Basic breaker-failure scheme time chart.......................................................................................................... 149 The breaker-failure protection scheme with fault detector supervision after the timer provides consistent delay. ........................................................................................................................................... 150 Subsidence decaying current flows in the CT secondary circuit after primary fault current interruption....... 150 Logic for detecting an open-phase condition in less than one cycle................................................................ 150 The open-phase detection logic operates in less than one cycle...................................................................... 151 The breaker-failure protection scheme with open-phase detector supervision provides fast reset.................. 151 Breaker-failure scheme with alternate initiation logic..................................................................................... 152 Breaker-failure protection logic for multiphase faults..................................................................................... 152 Breaker-failure protection logic for single-phase-to-ground faults. ................................................................ 152 Breaker-failure tripping logic in a substation with single-bus, single-breaker configuration.......................... 153 Breaker-failure tripping logic for a bus involving a transformer. .................................................................... 154 Breaker-failure tripping logic for a ring-bus configuration. ............................................................................ 154 Bus arrangement with four buses and eight terminals. .................................................................................... 155 Graphical description of a four-bus-zone, eight-terminal system. (a) Connection status when DS1, DS2, and DS3 are open. (b) Bus-zone-to-bus-zone connection status when DS1 is closed and DS2 and DS3 are open. (c) Protection zone formation with bus zones. (d) Protection zone formation with terminals..... 155 Check zone application example. .................................................................................................................... 156 Bus differential tripping algorithm. ................................................................................................................. 156 Breaker-failure tripping algorithm. .................................................................................................................. 156 SEL-300G generator relays provide protection, control, and monitoring functions for generators. ............... 160 SEL-700G generator relays provide protection, control, and monitoring functions for generators, including wind-driven units, and also intertie protection............................................................................. 160 Generator differential protection scheme......................................................................................................... 160 SEL-300G1 relay ac connection for a high-resistance-grounded generator with percentage differential protection...................................................................................................................................................... 161 Split-phase protection using flux-summing CTs. ............................................................................................ 162 Split-phase protection using percentage differential elements. ....................................................................... 162 SEL-300G1 relay ac connection for a high-resistance-grounded generator with split-phase protection using flux-summing CTs.............................................................................................................................. 162 SEL-300G1 relay ac connection for a high-resistance-grounded generator with split-phase protection using percentage differential elements. ........................................................................................................ 162 Generator high-resistance grounding using a distribution transformer............................................................ 163 Distribution of third-harmonic voltage for various operating conditions. (a) Normal operation. (b) Ground fault at the neutral point. (c) Ground fault at the generator terminals....................................... 163 A two-element stator ground fault protection scheme provides 100 percent coverage to generator windings. ...................................................................................................................................... 164 SEL-300G0 relay ac connection for a resistance-grounded generator with ground differential (87N) and ground overcurrent (50N/51N) elements. .................................................................................................... 165
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Figure 7.13 Figure 7.14 Figure 7.15 Figure 7.16 Figure 7.17 Figure 7.18 Figure 7.19 Figure 7.20 Figure 7.21 Figure 7.22 Figure 7.23 Figure 7.24 Figure 7.25 Figure 7.26 Figure 7.27 Figure 7.28 Figure 7.29 Figure 7.30 Figure 7.31 Figure 7.32 Figure 7.33 Figure 7.34 Figure 7.35 Figure 7.36 Figure 7.37 Figure 7.38 Figure 7.39 Figure 7.40 Figure 7.41 Figure 7.42 Figure 7.43 Figure 7.44 Figure 7.45 Figure 7.46 Figure 8.1 Figure 8.2 Figure 8.3 Figure 8.4 Figure 8.5 Figure 8.6 Figure 8.7 Figure 8.8 Figure 8.9 Figure 8.10 Figure 8.11 Figure 8.12 Figure 8.13 Figure 8.14
The SEL-2664 Field Ground Module measures the rotor winding insulation resistance and communicates the measured values to the SEL-300G or SEL-700G relay via a fiber-optic channel. .........166 The dc-switching method measures the field resistance to ground. The measured resistance is very high under normal conditions and lower for ground faults...................................................................................166 Voltage measured across the sensing resistor for normal and fault conditions. ...............................................166 Bridge equivalent circuit of the Figure 7.14 circuit. ........................................................................................166 Using an SEL-2600 series RTD module to convert the outputs from temperature sensors to optical signals avoids long copper wire runs and prevents induced noise and inaccuracies. ...............................................167 Electrical analog circuit of the first-order thermal model. ...............................................................................167 Time-current characteristics of the SEL-300G and SEL-700G negative-sequence overcurrent elements.......169 LOF protection using a negative-offset mho element. .....................................................................................169 Two-zone LOF protection using negative-offset mho elements.......................................................................170 Two-zone LOF protection using a negative-offset mho element and a positive-offset mho element with directional element supervision. ...................................................................................................................170 Setting the LOF Zone 2 element according to Figure 7.22 prevents the system from losing steady-state stability, but the generator lacks protection in the highlighted region, located between the capability curve and the LOF element Zone 2 characteristic. .......................................................................................171 In the P-Q plane representation, we directly use the capability curve and UEL characteristic from the manufacturer. With the setting corresponding to Figure 7.22, the generator lacks protection in the highlighted region.........................................................................................................................................171 Setting the LOF element characteristic between the generator capability curve and the UEL characteristic prevents the system from losing steady-state stability and protects the generator. ......................................171 The P-Q plane representation of Figure 7.25 shows the Zone 2 characteristic correctly set between the generator capability curve and the UEL characteristic.................................................................................172 Turbine blades require cooling. Without the cooling effect of steam passing over the blades of the turbine, overheating and damage can occur. ..............................................................................................................172 The SEL-300G relay includes a directional power element with two thresholds for generator motoring protection. .....................................................................................................................................................172 SEL-300G and SEL-700G dual-level, definite-time, volts-per-hertz characteristic. .......................................173 SEL-300G and SEL-700G composite inverse- and definite-time, volts-per-hertz characteristic. ...................173 Example turbine time-frequency characteristic................................................................................................174 Turbine time-frequency characteristic used to design the logic shown in Figure 7.33. ...................................175 Logic to provide turbine abnormal frequency protection according to Figure 7.32. .......................................175 Operating characteristic of the SEL-300G and SEL-700G single-blinder out-of-step protection scheme. .....175 Operating characteristic of the SEL-300G and SEL-700G double-blinder out-of-step protection scheme.....176 SEL-300G and SEL-700G inadvertent energization logic...............................................................................177 SEL-300G and SEL-700G logic for combined breaker-failure and breaker-flashover protection. .................177 Typical phase and ground backup protection for a directly connected generator. ...........................................177 Typical phase and ground backup protection for a generator with a step-up transformer. ..............................177 SEL-300G and SEL-700G voltage-restrained element pickup current varies with voltage. ...........................178 SEL-300G mho distance element characteristic. .............................................................................................178 SEL-300G2 relay ac connection for a high-resistance-grounded generator with synchronism-checking element and without differential protection..................................................................................................179 The alarm characteristic is formed by the capability curve and an active-power characteristic. .....................180 Recommended protection scheme for large generators. ..................................................................................180 An alternative protection scheme for large generators.....................................................................................181 Recommended protection scheme for small and medium generators..............................................................181 SSTP includes topology, current, and voltage processors................................................................................184 Current measurements for KCL check and measurement refinement. ............................................................184 Direct synchrophasor measurements provide better information than SCADA measurements and state estimation......................................................................................................................................................186 SVPs detect errors, refine measurements, and send the local estimates to the wide-area state estimator........187 SVP peer-to-peer communication provides redundancy. .................................................................................187 Scheme to supervise remote voltage measurements. .......................................................................................187 Transmission line model. .................................................................................................................................188 Real-time, MA-based disturbance detection system. .......................................................................................189 Oscillation-mode based decision and control logic..........................................................................................190 MA-based SIPS for a two-area power system with an interarea oscillation problem......................................190 Interarea active power transfer and decision and control logic outputs. ..........................................................191 SRP system used for the black-start exercise (courtesy of K. Koellner, SRP).................................................191 Frequencies of the islanded SRP system and the WECC system. ...................................................................191 SEL-5078 SYNCHROWAVE Console Software capture showing the moment of synchronization. ..................192
xxiii
Figure 8.15 Figure 8.16 Figure 8.17 Figure 8.18 Figure 8.19 Figure 8.20 Figure 8.21 Figure 8.22 Figure 8.23 Figure 8.24 Figure 8.25 Figure 8.26 Figure 8.27 Figure 8.28 Figure 8.29 Figure 8.30 Figure 8.31 Figure 8.32 Figure 8.33 Figure 8.34 Figure 8.35 Figure 8.36 Figure 8.37 Figure 8.38 Figure 8.39 Figure 8.40 Figure 8.41 Figure 8.42 Figure 8.43 Figure 8.44 Figure 8.45 Figure 8.46 Figure 8.47 Figure 8.48 Figure 8.49 Figure 8.50 Figure 8.51 Figure 8.52 Figure 8.53 Figure 8.54 Figure 8.55 Figure 8.56 Figure 8.57 Figure 8.58 Figure 9.1 Figure 9.2
Simplified representation of the LIPA system. ................................................................................................ 192 Adding shunt capacitance to a radial system decreases the system security margin....................................... 193 LIPA synchrophasor system: phasor measurements at 138 kV East Garden City substation and 23 kV Buell substation; synchrophasor processor at Hicksville headquarters. ...................................................... 193 An AGSS that uses voltage angle information has lower communications requirements and is more reliable than a traditional AGSS................................................................................................................... 194 Active-power transfer capability mainly depends on voltage angle difference and transmission link reactance when voltage magnitudes are close to nominal values................................................................. 194 When the parallel line in Figure 8.19 opens, voltage angle difference increases. ........................................ 194 Grijalva River hydroelectric complex, Chicoasйn-Angostura 400 kV transmission link with parallel 115 kV network and future link to Central America (courtesy of E. Martнnez, CFE). ................................ 195 Field measurement of the voltage angle difference between Chicoasйn and Angostura during switching of A3030 transmission line............................................................................................................................... 195 Oscillographic record, from the relay located at Chicoasйn, showing line currents, voltage at Chicoasйn, and angle difference element operation........................................................................................................ 195 Relays exchange synchrophasors for line backup protection in a two-terminal line application. ................... 196 FPI logic uses total negative-sequence and zero-sequence fault currents to identify the faulted phase(s)...... 196 Power system parameters and operating conditions to analyze RF coverage of the 87LQ and 67Q elements........................................................................................................................................................ 197 87LQ and 67Q have the same RF coverage for phase-to-ground faults when set to 0.1INOM sensitivity. Setting the 87LQ element to 0.05INOM improves the element RF coverage. ............................................... 197 Power system parameters and operating conditions to analyze 87LQ and 67Q element performance for a cross-country fault. .................................................................................................................................... 197 FPI, 87LQ, and 67Q operation for a cross-country fault. ................................................................................ 197 Distributed bus differential protection scheme for as many as 64 terminals uses relays at terminal locations and one SVP. ................................................................................................................................. 198 The distributed bus protection scheme uses the topology and current processors to determine the bus protection zones............................................................................................................................................ 198 Current differential element characteristic, external fault detection logic, and 87R output logic. .................. 198 Distributed bus differential protection for double bus and transfer bus with multiple terminals. ................... 199 Synchrophasor-based PSD logic...................................................................................................................... 200 OOSD logic uses angle difference information to identify OOS conditions................................................... 201 Operating characteristic of the OOSD element. .............................................................................................. 201 The OOST element uses slip frequency and acceleration information to detect unstable swings. ................. 201 SIPS suitable for two-area power systems that may use two relays, or two relays and one SVP, to prevent power system instability. .............................................................................................................................. 201 Implementation of the OOST element using the SVP. .................................................................................... 202 System model to analyze the performance of the OOST element in real time................................................ 202 Angle difference for stable operating conditions............................................................................................. 203 Angle difference for unstable operating conditions without remedial action.................................................. 203 Angle difference for unstable operating conditions and remedial action to maintain system stability. .......... 203 Trajectory on the angle difference-slip frequency plane for stable operating conditions................................ 203 Trajectory on the angle difference-slip frequency plane for unstable operating conditions............................ 203 Trajectories on the angle difference-slip frequency plane before and after the remedial action. .................... 204 Trajectory on the slip frequency-acceleration plane for stable operating conditions. ..................................... 204 Trajectory on the slip frequency-acceleration plane for unstable operating conditions. ................................. 204 Trajectories on the slip frequency-acceleration plane before and after the remedial action............................ 204 Implementation of the wide-area islanding detection element using the SVP................................................. 205 The combination of SEL local-area and wide-area elements provides fast islanding detection even when the DG capacity is close to the islanded area load. ...................................................................................... 205 Architecture of the SIPS implemented by IPCo. ............................................................................................. 206 Power system with two transmission lines feeding a constant power load. .................................................... 207 PV curves of the Figure 8.53 system for normal operating conditions and for operation with one of the transmission lines out of service. ................................................................................................................. 207 Power system model to study voltage stability. ............................................................................................... 207 Voltage magnitudes at buses 8 and 9 of the Figure 8.55 system. When two lines open, both voltages drop below 95 percent (the setting of definite-time undervoltage elements). .............................................. 208 Inverse-time undervoltage element characteristic for A = 28.2, B = 2, p = 2, and VPU = 0.95. ..................... 208 Voltage magnitudes at buses 8 and 9 of the Figure 8.55 system. The voltage at Bus 8 recovers immediately after the inverse-time undervoltage element at Bus 9 trips to drop the Bus 11 load............... 209 Power system communications example. ........................................................................................................ 213 Typical fiber-optic cable construction.............................................................................................................. 215
xxiv
Figure 9.3 Figure 9.4 Figure 9.5 Figure 9.6 Figure 9.7 Figure 9.8 Figure 9.9 Figure 9.10 Figure 9.11 Figure 9.12 Figure 9.13 Figure 9.14 Figure 9.15 Figure 9.16 Figure 9.17 Figure 9.18 Figure 9.19 Figure 9.20 Figure 9.21 Figure 9.22 Figure 9.23 Figure 9.24 Figure 9.25 Figure 9.26 Figure 9.27 Figure 9.28 Figure 10.1 Figure 10.2 Figure 10.3 Figure 10.4 Figure 10.5 Figure 10.6 Figure 10.7 Figure 10.8 Figure 10.9 Figure 10.10 Figure 10.11 Figure 10.12 Figure 10.13 Figure 10.14 Figure 10.15 Figure 10.16 Figure 10.17 Figure 10.18 Figure 10.19 Figure 10.20 Figure 10.21 Figure 10.22 Figure 10.23 Figure 11.1 Figure 11.2 Figure 11.3
Typical SM optical fiber attenuation as a function of wavelength. ..................................................................215 V-pin connector with the optional latching mechanism...................................................................................215 LC connector with the associated SFF transceiver module. ............................................................................216 SFP fiber-optic transceiver. ..............................................................................................................................216 SEL low-cost fiber-optic transceivers. .............................................................................................................217 SEL fiber-optic transceivers mount directly on the back of SEL relays. .........................................................217 SEL-2505 Remote I/O Module. .......................................................................................................................218 SEL-2506 Rack-Mount Remote I/O Module. ..................................................................................................218 SEL-2505 application example showing the amount of copper wiring replaced by a direct fiber-optic channel and remote I/O module cabinets......................................................................................................218 SEL-2600 Resistance Temperature Detector Module. .....................................................................................219 SEL-311L Line Current Differential Relay......................................................................................................220 SEL products with IEEE C37.94 fiber-optic interface.....................................................................................220 IEEE Standard C37.94 fiber-optic interface application examples..................................................................221 SEL Integrated Communications Optical Network in 19-inch shelf-mount and 8-inch panel-mount packages........................................................................................................................................................222 Example of network configuration using the SEL ICON. ...............................................................................223 SEL-3031 Serial Radio Transceiver. ................................................................................................................224 The SEL-3031 radio provides three serial links between, for example, a recloser control and the substation. .....................................................................................................................................................225 MIRRORED BITS protocol operation. ................................................................................................................227 Example of MIRRORED BITS channel-performance monitoring report. ...........................................................228 SEL-2100 Logic Processor...............................................................................................................................228 SEL-4388 MIRRORED BITS Tester. ...................................................................................................................229 SEL-4388 MIRRORED BITS Tester application example. .................................................................................229 VLAN segregated network...............................................................................................................................230 Layer 2 tagged Ethernet MAC header showing four-byte VLAN tag structure. .............................................230 SEL supports a wide range of Ethernet products. ............................................................................................231 Example of Google EarthTM-based fault report supplied by a distance relay. ..................................................234 Application example of OT and IT networks in an electric power system. .....................................................238 SEL IED communication connections replace isolated electromechanical devices with IED communication networks..............................................................................................................................241 SEL transceivers connect serial IED copper ports to fiber-optic serial and copper Ethernet LANs................241 SEL Ethernet interface test illustrating the ability to withstand ESD. .............................................................241 A star configuration provides a simple and reliable LAN................................................................................241 Multidrop LAN configuration. .........................................................................................................................242 Ring LANs allow for network segment failure and redirection. ......................................................................242 Example of SEL serial star LAN with IEDs connected via serial cables using nonroutable protocols with behavior similar to TDM-based communication..........................................................................................242 Example of SEL Ethernet star LAN with IEDs connected via Ethernet cables using routable protocols, which is an example of packet-based communication..................................................................................243 A redundant star-connected LAN using redundant ports corrects data flow failures faster than a ring- connected LAN looped among switch-mode IED ports...............................................................................244 High-performance, high-availability, simultaneous redundant data path network design. ..............................245 SEL-387 through-fault data model showing values, descriptions, context, and time stamp............................249 SEL information processors. ............................................................................................................................252 Information processor creating internal copy of SEL-351 relay database. ......................................................253 Information processor creating internal copies of non-SEL IED databases. ...................................................253 Information processor creating concentrated database with relevant subsets of IED database contents.........254 Tiered information processors creating concentrated databases with relevant subsets of IED database contents. ........................................................................................................................................................254 Serial network with all information processing functions in one box (an SEL communications processor or rugged computer). ....................................................................................................................257 Ethernet network with information processing functions split between two boxes (an SEL communications processor or rugged computer and an Ethernet switch)......................................257 SEL ICON bridges OT and IT by supporting both TDM- and packet-based communications. ......................257 SEL IEDs separate the processing of protection and automation logic. ..........................................................259 SEL IEDs separate user-defined protection and automation logic and variables. ...........................................259 SEL ease-of-use configuration software demonstrates separation of different unique groups of settings. .....260 Sam Spade, an Internet-based network reconnaissance application. ...............................................................266 Results of an Nmap TCP port scan with operating system detection activated. ..............................................267 Most SCADA protocols are susceptible to malicious frame injection attacks.................................................268
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Figure 11.4 Figure 11.5 Figure 11.6 Figure 11.7 Figure 11.8 Figure 11.9 Figure 11.10 Figure 11.11 Figure 11.12 Figure 11.13 Figure 11.14 Figure 11.15 Figure 11.16 Figure 12.1 Figure 12.2 Figure 12.3 Figure 12.4 Figure 12.5 Figure 12.6 Figure 12.7 Figure 12.8 Figure 12.9 Figure 12.10 Figure 12.11 Figure 12.12 Figure 12.13 Figure 12.14 Figure 12.15 Figure 12.16 Figure 12.17 Figure 12.18 Figure 12.19 Figure 13.1 Figure 13.2 Figure 13.3 Figure 13.4 Figure 13.5 Figure 13.6 Figure 13.7 Figure 13.8 Figure 13.9 Figure 13.10 Figure 13.11 Figure 13.12 Figure 13.13 Figure 13.14 Figure 13.15 Figure 13.16 Figure 13.17 Figure 13.18 Figure 13.19 Figure 13.20
Ethereal TCP/IP network sniffer analyzing captured DNP3 SCADA frames. ................................................ 268 Ethereal TCP/IP network sniffer displaying captured login prompt and password......................................... 269 The Back Orifice hijacking suite allows an attacker to completely take over a target PC. ............................. 270 Communications in the electric power industry provide for real-time protection, control, and monitoring, SCADA, and remote engineering access. .................................................................................................... 271 Barriers can prevent a successful electronic attack against SCADA or engineering networks. ...................... 271 ESP definitions for the Figure 11.7 network result in a perimeter around the SCADA LAN, the corporate LAN, and the substation or generation station LAN.................................................................... 272 Example of remote access to a relay via a transparent communications session through an SEL-2032 Communications Processor. ......................................................................................................................... 273 WAN links create electronic attack entry points.............................................................................................. 273 Use SEL-3021 Serial Encrypting Transceivers to protect multidrop or point-to-point SCADA networks. .... 274 SEL-3021 Serial Encrypting Transceivers protect vulnerable dial-up access links. ....................................... 274 Installing the SEL-3022 on the serial port of inaccessible IEDs, such as poletop recloser controls, implements secure, wireless engineering access connections...................................................................... 275 Inline cryptographic link security modules protect against attacks from outside the ESP, but not against attacks from within....................................................................................................................................... 276 Sequential events information collected from SEL devices contains status of security-related events........... 278 Failure rate patterns over time. Note that with maintenance during the wearout period, the failure rate can be restored to a lower level. ................................................................................................................... 282 MTBF and unavailability formulae for several system configurations. Each block represents a system component with constant failure and repair rates......................................................................................... 283 Fault tree for a simple overcurrent protection system...................................................................................... 284 Redundant line protection with Relay R1 and Relay R2 trip contacts (Out 1, Out 2) each connected to actuate a corresponding breaker trip coil (TC1, TC2). ................................................................................ 285 Aircraft dual primary systems of one manufacturer: same engines, same radios, same air-data computers, and same flight Management systems (courtesy of Cessna)...................................................... 286 Dual primary protection system with identical relays. .................................................................................... 286 Model of a dual protection system in which a common-mode component failure causes both relays to fail. 287 The single-board SEL-2431 Voltage Regulator Control has fewer cables, fewer interconnections, and higher reliability than multiboard designs.................................................................................................... 288 Real Time Digital Simulator for relay or protection scheme testing. .............................................................. 289 HALT chamber in SEL environmental test laboratory. ................................................................................... 289 Test at high stress to force and fix failures and widen operating margin......................................................... 289 Air electrostatic discharge to SEL product front-panel port............................................................................ 289 Environmental stress screening........................................................................................................................ 290 Ongoing reliability test. ................................................................................................................................... 290 Out-of-Box quality audit.................................................................................................................................. 290 SEL product hospital finds root cause and returns product in 72 hours. ......................................................... 291 Engineers analyze failure data to improve reliability....................................................................................... 291 Relay self-test report. ....................................................................................................................................... 292 Microprocessor-based relay self-testing and monitoring functions replace traditional routine tests. ............. 294 Record of breaker failure to close caused by dc supply voltage collapse........................................................ 299 DC monitoring terminals of SEL-421 relay..................................................................................................... 299 Circuit arrangement with PCM and breaker circuits common. ....................................................................... 300 Circuit arrangement with PCM and breaker circuits isolated.......................................................................... 301 DC circuit routing, radial system. .................................................................................................................... 301 DC circuit routing, radial system with switchyard routing.............................................................................. 301 Example close logic using contact logic.......................................................................................................... 302 Example close logic using programmable logic. ............................................................................................. 303 Trip circuit monitor logic................................................................................................................................. 304 Direct tripping example. .................................................................................................................................. 305 SEL-9502 Contact Arc Suppressor. ................................................................................................................. 306 RIO cabinet located in substation switchyard.................................................................................................. 307 Application example of RIO modules and fiber-optic links. ........................................................................... 308 Trip output logic with seal in for both internal and external trips. .................................................................. 308 Tripping multiple devices with one relay......................................................................................................... 309 SEL-451 relay with front-panel HMI suitable for local control. ..................................................................... 309 SEL-451 relay with independent controls for trip and close. .......................................................................... 310 Integrated control system design with separate local and Remote control systems.......................................... 311 SEL-3351 System Computing Platform. ......................................................................................................... 311 PCM system using serial star networks and dual relaying. ............................................................................. 312
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Figure 13.21 Figure 13.22 Figure 13.23 Figure 13.24 Figure 13.25 Figure 13.26 Figure 13.27 Figure 13.28 Figure 13.29 Figure 14.1 Figure 14.2 Figure 14.3 Figure 14.4 Figure 14.5 Figure 14.6 Figure 14.7 Figure 14.8
Example of cross-reference I/O table for a dc elementary diagram.................................................................316 Example of cross-reference table for I/O connected through a communications link. ....................................316 Example logic diagram.....................................................................................................................................317 Traditional duplex panels. ................................................................................................................................318 Modern simplex panel. .....................................................................................................................................318 Closed-back, swing-front PCM panels featuring SEL microprocessor-based relays and meter......................319 SEL POWERCORE Substation Control Enclosure. ...........................................................................................319 SEL POWERCORE using an ISO container for enclosure. ...............................................................................320 SEL POWERCORE-M. ......................................................................................................................................321 Elements of an asset management program [3]. ..............................................................................................324 Substation PCM system architecture................................................................................................................327 All substation data are available to the corporate servers. ...............................................................................330 Monitoring and controlling cooling fan operation reduce fan failures. ...........................................................332 Breaker air compressor monitoring provides early warning of impending compressor failures. ....................332 Capacitor bank monitoring provides early detection of control system problems...........................................333 HMI display of synchroscope using an SEL-451-4 relay for autosynchronizer. .............................................333 Typical substation control enclosure and weather information HMI screen....................................................334
List of Tables
Table 2.1 Table 2.2 Table 3.1 Table 4.1 Table 4.2 Table 4.3 Table 4.4 Table 4.5 Table 4.6 Table 4.7 Table 5.1 Table 5.2 Table 5.3 Table 8.1 Table 8.2 Table 8.3 Table 9.1 Table 9.2 Table 9.3 Table 9.4 Table 9.5 Table 9.6 Table 9.7 Table 10.1 Table 10.2 Table 11.1 Table 11.2 Table 12.1 Table 12.2 Table 13.1 Table 14.1 Table 14.2 Table 14.3 Table 14.4 Table 14.5 Table 14.6 Table 14.7
SEL-3378 function blocks and functions........................................................................................................... 22 Size of IEEE Standard C37.118 synchrophasor messages in the SEL-421, SEL-451, SEL-487E, and SEL-487V relays. ................................................................................................................. 26 Interconnection protection and supervision elements provided by SEL relays................................................. 46 Summary of transmission line protection challenges. ....................................................................................... 59 Comparison of transmission line protection principles. .................................................................................... 60 Voltage and current input signals to traditional phase and ground distance elements....................................... 63 Directional comparison scheme performance summary. ................................................................................... 81 Clearing times of directional comparison schemes for faults that plot in each region of Figure 4.38. ............. 82 Fault-resistance coverage of polarized-mho and quadrilateral ground distance elements [31]......................... 92 Secondary currents and voltages measured by a relay for an open phase in the parallel line and for a ground fault on the protected line [34].................................................................. 98 Harmonic content of the current signal shown in Figure 5.11......................................................................... 113 Comparison of independent even-harmonic restraint and common even-harmonic blocking methods. ......... 114 Transformer categories according to the IEEE Standard C57.12.00 [2]. ........................................................ 123 Operating times of 67Q, FPI, and 87LQ elements. ......................................................................................... 198 Scenarios to analyze the performance of the OOST element. ......................................................................... 202 Worst-case operating time budget calculation for the SIPS............................................................................. 206 Response times and event durations for different power system communications applications. .................... 212 Susceptibility to noise bursts per IEC Standard 60834-1. ............................................................................... 214 Communications path propagation delay as a function of path length............................................................ 214 Typical loss values for most popular optical fiber sizes. ................................................................................. 215 Ethernet SFP module capabilities (typical values). ......................................................................................... 216 Characteristics of the SEL-2800 series fiber-optic transceivers. ..................................................................... 217 Directional comparison scheme operating times. ............................................................................................ 232 Power system data that IEDs collect and create. ............................................................................................. 246 Popular network communications methods and their ability to satisfy networked IED tasks......................... 256 Password strength comparison in relays from different vendors. .................................................................... 276 Summary of multilevel password-authentication mechanism in SEL devices. ............................................... 277 Reliability measure definitions. ....................................................................................................................... 281 Reliability figures for use in fault trees............................................................................................................ 284 Need for independent control buttons.............................................................................................................. 310 Actual business case data for comparing substation upgrade program alternatives. ....................................... 326 Data point count for each substation................................................................................................................ 330 Power transformer data collected by SEL relays............................................................................................. 331 Tracking breaker wear indicators reduces maintenance budgets..................................................................... 332 Real-time capacitor bank performance indicators reduce maintenance costs. ................................................ 333 Battery and charger monitoring data points..................................................................................................... 333 Substation control enclosure and weather monitoring data points. ................................................................. 334

HJA Ferrer, EO Schweitzer

File: modern-solutions-for-protection-control-and-monitoring-of-electric.pdf
Title: ModernSolutions_.book
Author: HJA Ferrer, EO Schweitzer
Author: tinava
Published: Fri May 21 16:02:37 2010
Pages: 28
File size: 0.73 Mb


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