Power System Protective Relaying

727 Pages·2018·40.91 MB·English

by  J. C. Das

Power Systems Handbook
Power Systems Protective
Relaying
Volume 4
Power Systems Handbook
Series Author
J.C. Das
Power System Studies, Inc., Snellville, Georgia, USA
Volume 1: Short-Circuits in AC and DC Systems:
ANSI, IEEE, and IEC Standards
Volume 2: Load Flow Optimization and Optimal Power Flow
Volume 3: Harmonic Generation Effects Propagation and Control
Volume 4: Power Systems Protective Relaying
Power Systems Protective
Relaying
Volume 4
J.C. Das
CRC Press
Taylor & Francis Group
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Boca Raton, FL 33487-2742
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Library of Congress Cataloging‑in‑Publication Data
Names: Das, J. C., 1934- author.
Title: Power systems protective relaying / J.C. Das.
Description: Boca Raton : Taylor & Francis, a CRC title, part of the Taylor &
Francis imprint, a member of the Taylor & Francis Group, the academic
division of T&F Informa, plc, [2018] | Includes bibliographical references
and index.
Identifiers: LCCN 2017017946 | ISBN 9781498745505 (hardback : acid-free paper) |
ISBN 9781498745512 (ebook)
Subjects: LCSH: Protective relays. | Electric power systems--Protection.
Classification: LCC TK2861 .D33 2018 | DDC 621.31/7--dc23
LC record available at https://lccn.loc.gov/2017017946
Visit the Taylor & Francis Web site at
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and the CRC Press Web site at
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Contents
Series Preface ...............................................................................................................................xix
Preface to Volume 4: Power Systems Protective Relaying .....................................................xxi
Author .........................................................................................................................................xxiii
1. Modern Protective Relaying: An Overview .....................................................................1
1.1 Design Aspects and Reliability ...................................................................................1
1.2 Fundamental Power System Knowledge ...................................................................2
1.3 Design Criteria of Protective Systems ........................................................................3
1.3.1 Selectivity ..........................................................................................................3
1.3.2 Speed..................................................................................................................3
1.3.3 Reliability ..........................................................................................................4
1.4 Equipment and System Protection .............................................................................4
1.5 Unit Protection Systems ...............................................................................................5
1.5.1 Back-Up Protection ..........................................................................................7
1.6 Smart Grids ....................................................................................................................7
1.6.1 Framework for the Smart Grids .....................................................................7
1.6.2 Fundamental Layer ..........................................................................................9
1.6.2.1 Foundational Infrastructure and Resources ................................9
1.6.2.2 Organization and Process .............................................................10
1.6.2.3 Standards and Models ...................................................................10
1.6.2.4 Business and Regulatory ...............................................................10
1.6.3 Enabling Layer ...............................................................................................11
1.6.3.1 Enabling Infrastructure .................................................................11
1.6.3.2 Incremental Intelligence ................................................................11
1.6.4 Application Layer ...........................................................................................11
1.6.4.1 Grid and Customer Analysis ........................................................11
1.6.4.2 Real-Time Awareness and Control ..............................................11
1.6.4.3 Customer Interaction .....................................................................11
1.6.5 Innovation Layer ............................................................................................12
1.6.5.1 Research and Development ..........................................................12
1.6.5.2 Research and Demonstration Projects ........................................12
1.7 Load Profiles: Var–Volt Control .................................................................................12
1.8 Some Modern Technologies Leading to Smart Grids ............................................13
1.8.1 WAMSs and PMUs ........................................................................................14
1.8.2 System Integrity Protection Schemes ..........................................................16
1.8.3 Adaptive Protection .......................................................................................17
1.9 Cyber Security .............................................................................................................18
1.10 NERC and CIP Requirements ...................................................................................20
References ...............................................................................................................................22
2. Protective Relays ...................................................................................................................23
2.1 Classification of Relay Types .....................................................................................23
2.1.1 Input .................................................................................................................23
2.1.2 Operating Principle .......................................................................................23
v
vi Contents
2.1.3 Performance ....................................................................................................23
2.1.4 Construction ...................................................................................................24
2.2 Electromechanical Relays ..........................................................................................24
2.3 Overcurrent Relays .....................................................................................................26
2.3.1 ANSI Curves ...................................................................................................26
2.3.2 IEC Curves ......................................................................................................28
2.4 Differential Relays ......................................................................................................28
2.4.1 Overcurrent Differential Protection ............................................................29
2.4.2 Partial Differential Schemes .........................................................................34
2.4.3 Overlapping the Zones of Protection ..........................................................34
2.4.4 Percent Differential Relays ...........................................................................34
2.5 Pilot Wire Protection ..................................................................................................36
2.6 Directional Overcurrent Relays ................................................................................37
2.7 Voltage Relays ..............................................................................................................41
2.8 Reclosing Relays ..........................................................................................................45
2.9 Breaker Failure Relay..................................................................................................45
2.10 Machine Field Ground Fault Relay ...........................................................................46
2.11 Frequency Relays ........................................................................................................47
2.12 Distance Relays ............................................................................................................50
2.13 Other Relay Types .......................................................................................................52
References ...............................................................................................................................52
3. Instrument Transformers ....................................................................................................53
3.1 Accuracy Classification of CTs ..................................................................................53
3.1.1 Metering Accuracies ......................................................................................53
3.1.2 Relaying Accuracies ......................................................................................53
3.1.3 Relaying Accuracy Classification X.............................................................55
3.1.4 Accuracy Classification T .............................................................................55
3.2 Constructional Features of CTs .................................................................................56
3.3 Secondary Terminal Voltage Rating .........................................................................56
3.3.1 Saturation Voltage ..........................................................................................57
3.3.2 Saturation Factor ............................................................................................58
3.4 CT Ratio and Phase Angle Errors .............................................................................59
3.5 Interrelation of CT Ratio and Class C Accuracy.....................................................62
3.6 Polarity of Instrument Transformers .......................................................................64
3.7 Application Considerations .......................................................................................66
3.8 Series and Parallel Connections of CTs ...................................................................70
3.9 Transient Performance of the CTs .............................................................................70
3.9.1 C T Saturation Calculations ..........................................................................73
3.9.2 E ffect of Remanence ......................................................................................74
3.10 Practicality of CT Applications .................................................................................75
3.11 CTs for Low-Resistance Grounded Medium-Voltage Systems .............................76
3.12 Future Directions in CT Applications ......................................................................77
3.13 Voltage Transformers ..................................................................................................79
3.13.1 Rated Primary Voltage and Ratios ..............................................................79
3.13.2 Accuracy Rating .............................................................................................82
3.13.3 Thermal Burdens ...........................................................................................83
3.13.4 PT Connections ..............................................................................................83
3.13.5 Ferroresonance Damping .............................................................................84
Contents vii
3.14 Capacitor-Coupled Voltage Transformers ...............................................................84
3.14.1 Transient Performance ..................................................................................85
3.14.2 Applications to Distance Relay Protection .................................................88
3.15 Line (Wave) Traps ........................................................................................................88
3.16 Transducers ..................................................................................................................91
References ...............................................................................................................................91
4. Microprocessor-Based Multifunction Relays .................................................................93
4.1 Functionality ................................................................................................................93
4.1.1 Protection Features ........................................................................................93
4.1.2 Voltage-Based Protections ............................................................................93
4.1.3 Monitoring Features ......................................................................................94
4.1.4 Communications and Controls ....................................................................94
4.2 Front Panel ...................................................................................................................94
4.3 Environmental Compatibility ...................................................................................95
4.4 Dimensions ..................................................................................................................95
4.5 Specifications ...............................................................................................................95
4.6 Settings .......................................................................................................................101
4.6.1 The Setting Groups ......................................................................................101
4.7 Relay Bit Words .........................................................................................................106
4.8 Time Delay Overcurrent Protection .......................................................................106
4.9 Voltage-Based Elements ...........................................................................................111
4.10 Power Elements .........................................................................................................113
4.11 Loss of Potential ........................................................................................................114
4.12 Frequency Settings....................................................................................................114
4.13 Trip and Close Logic .................................................................................................114
4.13.1 Trip Logic ......................................................................................................114
4.13.2 Close Logic ....................................................................................................118
4.13.3 Reclose Logic and Supervision ..................................................................119
4.14 Demand Metering .....................................................................................................120
4.15 Logical Settings .........................................................................................................122
4.16 Latch Bits: Nonvolatile State ....................................................................................123
4.17 Global Settings ..........................................................................................................124
4.18 Port Settings ...............................................................................................................125
4.19 Breaker Monitor ........................................................................................................125
4.20 Front Panel Operations.............................................................................................127
4.20.1 Rotating Display ..........................................................................................130
4.21 Analyzing Events ......................................................................................................130
4.21.1 Sequential Event Recorder ..........................................................................131
4.21.2 Triggering ......................................................................................................131
4.21.3 Aliases ...........................................................................................................131
4.22 Setting the Relay .......................................................................................................132
Reference ...............................................................................................................................133
5. Current Interruption Devices and Battery Systems ....................................................135
5.1 High-Voltage Circuit Breakers.................................................................................135
5.1.1 DC Control Schematics ...............................................................................137
5.2 Battery Systems .........................................................................................................138
5.2.1 Battery Types ................................................................................................138
viii Contents
5.2.2 Plante Batteries .............................................................................................139
5.2.3 Pasted Plate Batteries ...................................................................................140
5.2.4 Tubular Plate Batteries ................................................................................140
5.2.5 Sealed (Valve-Regulated) Lead Acid Batteries ........................................140
5.2.6 Battery Monitoring System .........................................................................141
5.2.7 Nickel–Cadmium Batteries ........................................................................142
5.2.8 Pocket Plate Nickel–Cadmium Batteries ..................................................142
5.3 Sizing the Batteries ...................................................................................................143
5.3.1 Standards for Sizing the Batteries .............................................................144
5.3.2 System Configurations for Batteries ..........................................................144
5.3.3 Automatic Transfer Switches......................................................................145
5.3.4 Battery Chargers ..........................................................................................147
5.3.4.1 Floating Operation .......................................................................147
5.3.4.2 Equalizing Charge .......................................................................148
5.3.4.3 Switch Mode Operation ...............................................................148
5.3.5 Battery Charger as a Battery Eliminator ..................................................148
5.3.6 Short-Circuit and Coordination Considerations .....................................148
5.4 Capacitive Trip Devices ............................................................................................149
5.5 Lockout Relays...........................................................................................................149
5.6 Remote Trips ..............................................................................................................150
5.7 CT and PT Test Switches ..........................................................................................151
5.8 Fuses............................................................................................................................151
5.8.1 Medium-Voltage Fuses ................................................................................155
5.8.1.1 Variations in the Fuse Time–Current Characteristics ............159
5.8.2 Selection of Fuse Types and Ratings .........................................................159
5.8.3 Semiconductor Fuses ...................................................................................161
5.9 Low-Voltage Circuit Breakers ..................................................................................162
5.9.1 Molded Case Circuit Breakers ...................................................................162
5.9.2 Current-Limiting MCCBs ...........................................................................164
5.9.3 Insulated Case Circuit Breakers ................................................................168
5.9.4 Low-Voltage Power Circuit Breakers .........................................................168
5.9.5 Short-Time Bands of LVPCBs’ Trip Programmers ..................................169
5.9.6 Motor Circuit Protectors .............................................................................171
5.9.7 Other Pertinent Data of Low-Voltage Circuit Breakers ..........................172
5.10 Selective Zone Interlocking .....................................................................................173
5.11 Electronic Power Fuses .............................................................................................175
5.12 Low- and Medium-Voltage Contactors ..................................................................176
References .............................................................................................................................179
6. Overcurrent Protection: Ideal and Practical..................................................................181
6.1 Fundamental Considerations ..................................................................................181
6.2 Data for the Coordination Study ............................................................................182
6.3 Computer-Based Coordination ...............................................................................183
6.4 Initial Analysis ..........................................................................................................184
6.5 Coordinating Time Interval .....................................................................................184
6.5.1 Relay Overtravel ..........................................................................................184
6.6 Fundamental Considerations for Coordination ...................................................185
6.6.1 Settings on Bends of Coordination Curves ..............................................186
6.7 Some Examples of Coordination ............................................................................186
Contents ix
6.7.1 Low-Voltage Distribution System ..............................................................186
6.7.2 2.4 kV Distribution .......................................................................................192
6.7.3 Ground Fault Protection .............................................................................196
6.7.4 Coordination in a Cogeneration System ...................................................197
6.8 Coordination on Instantaneous Basis ....................................................................199
6.8.1 Selectivity between Two Series-Connected
Current-Limiting Fuses ...............................................................................200
6.8.2 Selectivity of a Current-Limiting Fuse Downstream of
Noncurrent-Limiting Circuit Breaker .......................................................203
6.8.3 Selectivity of Current-Limiting Devices in Series ...................................207
6.9 NEC Requirements of Selectivity ...........................................................................211
6.9.1 Fully Selective Systems ...............................................................................212
6.9.2 Selection of Equipment Ratings and Trip Devices ..................................214
6.10 The Art of Compromise ...........................................................................................215
6.11 Zone Selective Interlocking .....................................................................................221
6.12 Protection and Coordination of UPS Systems ......................................................227
References .............................................................................................................................230
7. System Grounding .............................................................................................................231
7.1 Study of Grounding Systems ..................................................................................231
7.2 Solidly Grounded Systems ......................................................................................232
7.2.1 Hazards in Solidly Grounded Systems ....................................................235
7.3 Low-Resistance Grounded Systems .......................................................................236
7.4 High-Resistance Grounded Systems ......................................................................237
7.5 Ungrounded Systems ...............................................................................................239
7.6 Reactance Grounding ...............................................................................................241
7.7 Resonant Grounding ................................................................................................242
7.8 Corner of Delta Grounded Systems........................................................................242
7.9 Artificially Derived Neutrals ..................................................................................243
7.10 Multiple Grounded Systems ....................................................................................245
7.10.1 Equivalent Circuit of Multiple Grounded Systems .................................246
7.11 NEC and NESC Requirements ...............................................................................247
7.12 Hybrid Grounding System for Industrial Bus-Connected Generators .............248
7.13 Grounding of ASDs ..................................................................................................249
7.14 Grounding in Mine Installations ............................................................................253
References .............................................................................................................................254
8. Ground Fault Protection ....................................................................................................257
8.1 Protection and Coordination in Solidly Grounded Systems ..............................257
8.1.1 NEC Requirements ......................................................................................257
8.1.2 Self-Extinguishing Ground Faults .............................................................263
8.1.3 Improving Coordination in Solidly Grounded
Low-Voltage Systems .................................................................................. 263
8.2 Ground Fault Coordination in Low-Resistance Grounded Medium-
Voltage Systems .........................................................................................................266
8.3 Remote Tripping ........................................................................................................268
8.4 Ground Fault Protection in Ungrounded Systems ...............................................268
8.4.1 Nondiscriminatory Alarms and Trips ......................................................270
8.5 Ground Fault Protection in High-Resistance Grounded Systems .....................271