Preface to the Fourth Edition xi
Preface to the Third Edition xii
Preface to the Second Edition xiii
Preface to the First Edition xiv
1 Introduction to Protective Relaying 1
1.1 What is Relaying? 1
1.2 Power System Structural Considerations 2
1.3 Power System Bus Configurations 4
1.4 The Nature of Relaying 8
1.5 Elements of a Protection System 14
1.6 International Practices 18
1.7 Summary 19
Problems 19
References 23
2 Relay Operating Principles 25
2.1 Introduction 25
2.2 Detection of Faults 26
2.3 Relay Designs 30
2.4 Electromechanical Relays 31
2.5 Solid-State Relays 40
2.6 Computer Relays 44
2.7 Other Relay Design Considerations 45
2.8 Control Circuits: A Beginning 48
2.9 Summary 49
Problems 49
References 51
3 Current and Voltage Transformers 53
3.1 Introduction 53
3.2 Steady-State Performance of Current Transformers 54
3.3 Transient Performance of Current Transformers 61
3.4 Special Connections of Current Transformers 64
3.5 Linear Couplers and Electronic Current Transformers 67
3.6 Voltage Transformers 68
3.7 Coupling Capacitor Voltage Transformers 69
3.8 Transient Performance of CCVTs 72
3.9 Electronic Voltage Transformers 75
3.10 Summary 76
Problems 76
References 78
4 Nonpilot Overcurrent Protection of Transmission Lines 79
4.1 Introduction 79
4.2 Fuses, Sectionalizers, and Reclosers 81
4.3 Inverse, Time-Delay Overcurrent Relays 84
4.4 Instantaneous Overcurrent Relays 94
4.5 Directional Overcurrent Relays 96
4.6 Polarizing 98
4.7 Summary 102
Problems 102
References 105
5 Nonpilot Distance Protection of Transmission Lines 107
5.1 Introduction 107
5.2 Stepped Distance Protection 107
5.3 R-X Diagram 110
5.4 Three-Phase Distance Relays 114
5.5 Distance Relay Types 123
5.6 Relay Operation with Zero Voltage 124
5.7 Polyphase Relays 125
5.8 Relays for Multiterminal Lines 126
5.9 Protection of Parallel Lines 129
5.10 Effect of Transmission Line Compensation Devices 132
5.11 Loadability of Relays 134
5.12 Summary 136
Problems 136
References 138
6 Pilot Protection of Transmission Lines 139
6.1 Introduction 139
6.2 Communication Channels 140
6.3 Tripping Versus Blocking 144
6.4 Directional Comparison Blocking 145
6.5 Directional Comparison Unblocking 149
6.6 Underreaching Transfer Trip 150
6.7 Permissive Overreaching Transfer Trip 153
6.8 Permissive Underreaching Transfer Trip 154
6.9 Phase Comparison Relaying 155
6.10 Current Differential 158
6.11 Pilot Wire Relaying 159
6.12 Multiterminal Lines 160
6.13 The Smart Grid 163
6.14 Summary 163
Problems 164
References 165
7 Rotating Machinery Protection 167
7.1 Introduction 167
7.2 Stator Faults 168
7.3 Rotor Faults 183
7.4 Unbalanced Currents 184
7.5 Overload 184
7.6 Overspeed 186
7.7 Abnormal Voltages and Frequencies 187
7.8 Loss of Excitation 188
7.9 Loss of Synchronism 189
7.10 Power Plant Auxiliary System 190
7.11 Winding Connections 196
7.12 Startup and Motoring 196
7.13 Inadvertent Energization 198
7.14 Torsional Vibration 200
7.15 Sequential Tripping 200
7.16 Summary 201
Problems 202
References 204
8 Transformer Protection 207
8.1 Introduction 207
8.2 Overcurrent Protection 208
8.3 Percentage Differential Protection 210
8.4 Causes of False Differential Currents 213
8.5 Supervised Differential Relays 219
8.6 Three-Phase Transformer Protection 221
8.7 Volts-per-Hertz Protection 226
8.8 Nonelectrical Protection 227
8.9 Protection Systems for Transformers 228
8.10 Summary 234
Problems 234
References 236
9 Bus, Reactor, and Capacitor Protection 237
9.1 Introduction to Bus Protection 237
9.2 Overcurrent Relays 238
9.3 Percentage Differential Relays 238
9.4 High-Impedance Voltage Relays 239
9.5 Moderately High-Impedance Relay 241
9.6 Linear Couplers 241
9.7 Directional Comparison 242
9.8 Partial Differential Protection 243
9.9 Introduction to Shunt Reactor Protection 244
9.10 Dry-Type Reactors 245
9.11 Oil-Immersed Reactors 247
9.12 Introduction to Shunt Capacitor Bank Protection 248
9.13 Static Var Compensator Protection 250
9.14 Static Compensator 252
9.15 Summary 252
Problems 253
References 254
10 Power System Phenomena and Relaying Considerations 255
10.1 Introduction 255
10.2 Power System Stability 255
10.3 Steady-State Stability 256
10.4 Transient Stability 261
10.5 Voltage Stability 266
10.6 Dynamics of System Frequency 267
10.7 Series Capacitors and Reactors 270
10.8 Independent Power Producers 271
10.9 Islanding 272
10.10 Blackouts and Restoration 272
10.11 Summary 275
Problems 275
References 276
11 Relaying for System Performance 277
11.1 Introduction 277
11.2 System Integrity Protection Schemes 277
11.3 Underfrequency Load Shedding 278
11.4 Undervoltage Load Shedding 280
11.5 Out-of-Step Relaying 281
11.6 Loss-of-Field Relaying 285
11.7 Adaptive relaying 285
11.8 Hidden Failures 288
11.9 Distance Relay Polarizing 289
11.10 Summary 292
Problems 292
References 292
12 Switching Schemes and Procedures 293
12.1 Introduction 293
12.2 Relay Testing 293
12.3 Computer Programs for Relay Setting 295
12.4 Breaker Failure Relaying 296
12.5 Reclosing 299
12.6 Single-Phase Operation 300
12.7 Summary 300
References 300
13 Monitoring Performance of Power Systems 301
13.1 Introduction 301
13.2 Oscillograph Analysis 302
13.3 Synchronized Sampling 309
13.4 Fault Location 311
13.5 Alarms 316
13.6 COMTRADE and SYNCHROPHASOR Standards 318
13.7 Summary 319
Problems 320
References 322
14 Improved Protection with Wide Area Measurements (WAMS) 323
14.1 Introduction 323
14.2 WAMS Organization 323
14.3 Using WAMS for Protection 324
14.4 Supervising Backup Protection 326
14.5 Impedance Excursions into Relay Settings 327
14.6 Stability-Related Protections 328
14.7 SIPS and Control with WAMS 333
14.8 Summary and Future Prospects 334
References 334
15 Protection Considerations for Renewable Resources 337
James K. Niemira, P.E.
15.1 Introduction 337
15.2 Types of Renewable Generation 337
15.3 Connections to the Power Grid and Protection Considerations 344
15.4 Grid Codes for Connection of Renewables 351
15.5 Summary 355
References 355
Appendix A: IEEE Device Numbers and Functions 357
Appendix B: Symmetrical Components 359
Appendix C: Power Equipment Parameters 365
Appendix D: Inverse Time Overcurrent Relay Characteristics 369
Index 373
