Author Biographies xxv
Preface to the Second Edition xxvii
List of Symbols xxix
Part I Protective Devices and Controls 1
1 Introduction 3
1.1 Power System Protection 3
1.2 Prevention and Control of System Failure 3
1.3 Protective System Design Considerations 8
1.4 Definitions Used in System Protection 9
1.5 System Disturbances 11
1.6 Book Contents 12
Problems 14
References 15
2 Protection Measurements and Controls 17
2.1 Graphic Symbols and Device Identification 17
2.2 Typical Relay Connections 19
2.3 Circuit Breaker Control Circuits 22
2.4 Instrument Transformers 23
2.5 Relay Control Configurations 37
2.6 Optical Communications 38
Problems 42
References 44
3 Protective Device Characteristics 47
3.1 Introduction 47
3.2 Fuse Characteristics 48
3.3 Relay Characteristics 61
3.4 Power Circuit Breakers 87
3.5 Automatic Circuit Reclosers 93
3.6 Automatic Line Sectionalizers 98
3.7 Circuit Switchers 100
3.8 Digital Fault Recorders 101
Problems 103
References 103
4 Relay Logic 109
4.1 Introduction 109
4.2 Electromechanical Relay Logic 110
4.3 Electronic Logic Circuits 111
4.4 Analog Relay Logic 125
4.5 Digital Relay Logic 128
4.6 Hybrid Relay Logic 139
4.7 Relays as Comparators 140
Problems 153
References 157
5 System Characteristics 163
5.1 Power System Faults 163
5.2 Station Arrangements 176
5.3 Overhead Line Impedances 182
5.4 Computation of Available Fault Current 184
5.5 System Equivalent for Protection Studies 188
5.6 The Compensation Theorem 202
5.7 Compensation Applications in Fault Studies 205
Problems 210
References 214
Part II Protection Concepts 215
6 Fault Protection of Radial Lines 217
6.1 Radial Distribution Systems 217
6.2 Radial Distribution Coordination 219
6.3 Radial Line Fault Current Calculations 222
6.4 Radial System Protective Strategy 233
6.5 Coordination of Protective Devices 236
6.6 Relay Coordination on Radial Lines 241
6.7 Coordinating Protective Devices Measuring Different Parameters 258
Problems 269
References 276
7 Introduction to Transmission Protection 277
7.1 Introduction 277
7.2 Protection with Overcurrent Relays 278
7.3 Distance Protection of Lines 285
7.4 Unit Protection 299
7.5 Ground Fault Protection 301
7.6 Summary 310
Problems 311
References 315
8 Complex Loci in the Z and Y Planes 317
8.1 The Inverse Z Transformation 317
8.2 Line and Circle Mapping 320
8.3 The Complex Equation of a Line 327
8.4 The Complex Equation of a Circle 328
8.5 Inversion of an Arbitrary Admittance 330
8.6 Inversion of a Straight Line Through (1, 0) 333
8.7 Inversion of an Arbitrary Straight Line 335
8.8 Inversion of a Circle with Center at (1, 0) 336
8.9 Inversion of an Arbitrary Circle 338
8.10 Summary of Line and Circle Inversions 340
8.11 Angle Preservation in Conformal Mapping 341
8.12 Orthogonal Trajectories 342
8.13 Impedance at the Relay 346
Problems 348
References 350
9 Impedance at the Relay 351
9.1 The Relay Apparent Impedance, ZR 351
9.2 Protection Equivalent M Parameters 353
9.3 The Circle Loci Z = P/(1±YK) 356
9.4 ZR Loci Construction 357
9.5 Relay Apparent Impedance 363
9.6 Relay Impedance for a Special Case 371
9.7 Construction of M Circles 375
9.8 Phase Comparison Apparent Impedance 378
Problems 384
References 388
10 Admittance at the Relay 391
10.1 Admittance Diagrams 391
10.2 Input Admittance Loci 392
10.3 The Relay Admittance Characteristic 395
10.4 Parallel Transmission Lines 400
10.5 Typical Admittance Plane Characteristics 404
10.6 Summary of Admittance Characteristics 407
Problems 408
Reference 411
Part III Transmission Protection 413
11 Analysis of Distance Protection 415
11.1 Introduction 415
11.2 Analysis of Transmission Line Faults 415
11.3 Impedance at the Relay 429
11.4 Distance Relay Settings 439
11.5 Ground Distance Protection 447
11.6 Distance Relay Coordination 449
Problems 452
References 454
12 Transmission Line Mutual Induction 457
12.1 Introduction 457
12.2 Line Impedances 458
12.3 Effect of Mutual Coupling 469
12.4 Short Transmission Line Equivalents 476
12.5 Long Transmission Lines 484
12.6 Long Transmission Line Equivalents 493
12.7 Solution of the Long-line Case 501
Problems 504
References 507
13 Pilot Protection Systems 509
13.1 Introduction 510
13.2 Physical Systems for Pilot Protection 512
13.3 Non-unit Pilot Protection Schemes 523
13.4 Unit Protection Pilot Schemes 536
13.5 An Example of EHV Line Protection 548
13.6 Pilot Protection Settings 554
13.7 Traveling Wave Relays 561
13.8 Monitoring of Pilot Performance 567
Problems 567
References 569
14 Complex Transmission Protection 573
14.1 Introduction 573
14.2 Single-phase Switching of Extra-high-voltage Lines 573
14.3 Protection of Multiterminal Lines 581
14.4 Protection of Mutually Coupled Lines 590
Problems 613
References 617
15 Series Compensated Line Protection 619
15.1 Introduction 619
15.2 Faults with Unbypassed Series Capacitors 621
15.3 Series Capacitor Bank Protection 634
15.4 Relay Problems Due to Compensation 653
15.5 Protection of Series Compensated Lines 674
15.6 Line Protection Experience 678
Problems 680
References 683
Part IV Apparatus Protection 685
16 Bus Protection 687
16.1 Introduction 687
16.2 Bus Configurations and Faults 688
16.3 Bus Protection Requirements 689
16.4 Bus Protection by Backup Line Relays 691
16.5 Bus Differential Protection 692
16.6 Other Types of Bus Protection 708
16.7 Auxiliary Tripping Relays 716
16.8 Summary 717
Problems 717
References 719
17 Transformer and Reactor Protection 721
17.1 Introduction 721
17.2 Transformer Faults 722
17.3 Magnetizing Inrush 729
17.4 Protection Against Incipient Faults 732
17.5 Protection Against Active Faults 735
17.6 Combined Line and Transformer Schemes 748
17.7 Regulating Transformer Protection 750
17.8 Shunt Reactor Protection 752
17.9 Static Var Compensator Protection 755
Problems 759
References 761
18 Generator Protection 763
18.1 Introduction 763
18.2 Generator System Configurations and Types of Protection 764
18.3 Stator Protection 766
18.4 Rotor Protection 781
18.5 Loss of Excitation Protection 785
18.6 Other Generator Protection Systems 789
18.7 Summary of Generator Protection 794
Problems 800
References 803
19 Motor Protection 805
19.1 Introduction 805
19.2 Induction Motor Analysis 806
19.3 Induction Motor Heating 824
19.4 Motor Problems 837
19.5 Classifications of Motors 843
19.6 Stator Protection 845
19.7 Rotor Protection 851
19.8 Other Motor Protections 852
19.9 Summary of Large Motor Protections 853
Problems 854
References 858
Part V System Aspects of Protection 861
20 Protection Against Abnormal System Frequency 863
20.1 Abnormal Frequency Operation 863
20.2 Effects of Frequency on the Generator 864
20.3 Frequency Effects on the Turbine 866
20.4 A System Frequency Response Model 869
20.5 Off Normal Frequency Protection 886
20.6 Steam Turbine Frequency Protection 887
20.7 Underfrequency Protection 889
Problems 903
References 905
21 Protective Schemes for Stability Enhancement 909
21.1 Introduction 909
21.2 Review of Stability Fundamentals 909
21.3 System Transient Behavior 918
21.4 Automatic Reclosing 929
21.5 Loss of Synchronism Protection 949
21.6 Voltage Stability and Voltage Collapse 957
21.7 System Integrity Protection Schemes (SIPS) 960
21.8 Summary 968
Problems 968
References 970
22 Line Commutated Converter HVDC Protection 973
22.1 Introduction 973
22.2 LCC Dc Conversion Fundamentals 974
22.3 Converter Station Design 992
22.4 Ac Side Protection 999
22.5 Dc Side Protection Overview 1002
22.6 Special HVDC Protections 1012
22.7 HVDC Protection Settings 1015
22.8 Summary 1016
Problems 1016
References 1018
23 Voltage Source Converter HVDC Protection 1021
23.1 Introduction 1021
23.2 VSC HVDC Fundamentals 1022
23.3 Converter Control Systems 1028
23.4 HVDC Response to Ac System Faults 1030
23.5 Ac System Protection 1031
23.6 Dc Faults 1035
23.7 Multiterminal Systems 1037
23.8 Hybrid LCC-VSC Systems 1037
23.9 Summary 1038
Problems 1038
References 1039
24 Protection of Independent Power Producer Interconnections 1041
24.1 Introduction 1041
24.2 Renewable Resources 1042
24.3 Transmission Interconnections 1042
24.4 Distribution Interconnections 1053
24.5 Summary 1060
Problems 1061
References 1061
25 SSR and SSCI Protection 1063
25.1 Introduction 1063
25.2 SSR Overview 1063
25.3 SSR and SSCI System Countermeasures 1073
25.4 SSR Source Countermeasures 1079
25.5 Summary 1093
Problems 1093
References 1095
Part VI Reliability of Protective Systems 1101
26 Basic Reliability Concepts 1103
26.1 Introduction 1103
26.2 Probability Fundamentals 1103
26.3 Random Variables 1110
26.4 Failure Definitions and Failure Modes 1127
26.5 Reliability Models 1129
Problems 1141
References 1143
27 Reliability Analysis 1145
27.1 Reliability Block Diagrams 1145
27.2 Fault Trees 1154
27.3 Reliability Evaluation 1166
27.4 Other Analytical Methods 1174
27.5 State Space and Markov Processes 1182
Problems 1190
References 1195
28 Reliability Concepts in System Protection 1197
28.1 Introduction 1197
28.2 System Disturbance Models 1197
28.3 Time-Independent Reliability Models 1208
28.4 Time-Dependent Reliability Models 1246
Problems 1256
References 1259
29 Fault Tree Analysis of Protective Systems 1261
29.1 Introduction 1261
29.2 Fault Tree Analysis 1262
29.3 Analysis of Transmission Protection 1273
29.4 Fault Tree Evaluation 1297
Problems 1306
References 1310
30 Markov Modeling of Protective Systems 1311
30.1 Introduction 1311
30.2 Testing of Protective Systems 1312
30.3 Modeling of Inspected Systems 1317
30.4 Monitoring and Self-testing 1331
30.5 The Unreadiness Probability 1337
30.6 Protection Abnormal Unavailability 1341
30.7 Evaluation of Safeguard Systems 1350
References 1356
Appendix A Protection Terminology 1359
A.1 Protection Terms and Definitions 1359
A.2 Relay Terms and Definitions 1361
A.3 Classification of Relay Systems 1363
A.4 Circuit Breaker Terms and Definitions 1366
References 1368
Appendix B Protective Device Classification 1371
B.1 Device Function Numbers 1371
B.2 Devices Performing More than One Function 1371
B.2.1 Suffix Numbers 1373
B.2.2 Suffix Letters 1373
B.2.3 Representation of Device Contacts on Electrical Diagrams 1374
Appendix C Overhead Line Impedances 1375
References 1387
Appendix D Transformer Data 1389
Appendix E 500 kV Transmission Line Data 1393
E.1 Tower Design 1393
E.2 Unit Length Electrical Characteristics 1393
E.3 Total Line Impedance and Admittance 1394
E.4 Nominal Pi 1395
E.5 ABCD Parameters 1395
E.6 Equivalent Pi 1395
E.7 Surge Impedance Loading 1397
E.8 Normalization 1399
E.9 Line Ratings and Operating Limits 1399
References 1400
Index 1401
