Electric Power Systems

Preface to First Edition ix
Preface to Fourth Edition xi
Preface to Fifth Edition xiii
Symbols xv

1 Introduction 1
1.1 History 1
1.2 Characteristics Influencing Generation and Transmission 2
1.3 Operation of Generators 4
1.4 Energy Conversion 5
1.5 Renewable Energy Sources 12
1.6 Energy Storage 17
1.7 Environmental Aspects of Electrical Energy 23
1.8 Transmission and Distribution Systems 27
1.9 Utilization 40
Problems 43

2 Basic Concepts 45
2.1 Three-Phase Systems 45
2.2 Three-Phase Transformers 55
2.3 Active and Reactive Power 57
2.4 The Per-Unit System 61
2.5 Power Transfer and Reactive Power 68
2.6 Harmonics in Three-Phase Systems 74
2.7 Useful Network Theory 75
Problems 78

3 Components of a Power System 83
3.1 Introduction 83
3.2 Synchronous Machines 83
3.3 Equivalent Circuit Under Balanced Short-Circuit Conditions 90
3.4 Synchronous Generators in Parallel 94
3.5 The Operation of a Generator on an Infinite Busbar 95
3.6 Automatic Voltage Regulators (AVRs) 100
3.7 Lines, Cables and Transformers 103
3.8 Transformers 124
3.9 Voltage Characteristics of Loads 131
Problems 134

4 Control of Power and Frequency 139
4.1 Introduction 139
4.2 The Turbine Governor 142
4.3 Control Loops 146
4.4 Division of Load between Generators 147
4.5 The Power-Frequency Characteristic of an Interconnected System 151
4.6 System Connected by Lines of Relatively Small Capacity 152
Problems 159

5 Control of Voltage and Reactive Power 161
5.1 Introduction 161
5.2 The Generation and Absorption of Reactive Power 163
5.3 Relation between Voltage, Power, and Reactive Power at a Node 165
5.4 Methods of Voltage Control: (a) Injection of Reactive Power 170
5.5 Methods of Voltage Control: (b) Tap-Changing Transformers 176
5.6 Combined Use of Tap-Changing Transformers and Reactive-Power Injection 183
5.7 Phase-Shift Transformer 188
5.8 Voltage Collapse 191
5.9 Voltage Control in Distribution Networks 195
5.10 Long Lines 197
5.11 General System Considerations 198
Problems 200

6 Load Flows 205
6.1 Introduction 205
6.2 Circuit Analysis Versus Load Flow Analysis 206
6.3 Gauss-Seidel Method 212
6.4 Load Flows in Radial and Simple Loop Networks 216
6.5 Load Flows in Large Systems 219
6.6 Computer Simulations 231
Problems 234

7 Fault Analysis 239
7.1 Introduction 239
7.2 Calculation of Three-Phase Balanced Fault Currents 241
7.3 Method of Symmetrical Components 247
7.4 Representation of Plant in the Phase-Sequence Networks 251
7.5 Types of Fault 252
7.6 Fault Levels in a Typical System 259
7.7 Power in Symmetrical Components 265
7.8 Systematic Methods for Fault Analysis in Large Networks 265
7.9 Neutral Grounding 270
7.10 Interference with Communication Circuits–Electromagnetic Compatibility (EMC) 274
Problems 275

8 System Stability 281
8.1 Introduction 281
8.2 Equation of Motion of a Rotating Machine 283
8.3 Steady-State Stability 284
8.4 Transient Stability 287
8.5 Transient Stability–Consideration of Time 293
8.6 Transient Stability Calculations by Computer 298
8.7 Dynamic or Small-Signal Stability 301
8.8 Stability of Loads Leading to Voltage Collapse 305
8.9 Further Aspects 309
8.10 Multi-Machine Systems 311
8.11 Transient Energy Functions (TEF) 312
8.12 Improvement of System Stability 314
Problems 315

9 Direct-Current Transmission 319
9.1 Introduction 319
9.2 Current Source and Voltage Source Converters 320
9.3 Semiconductor Valves for High-Voltage Direct-Current Converters 322
9.4 Current Source Converter h.v.d.c. 325
9.5 Voltage Source Converter h.v.d.c. 346
Problems 352

10 Overvoltages and Insulation Requirements 355
10.1 Introduction 355
10.2 Generation of Overvoltages 356
10.3 Protection Against Overvoltages 365
10.4 Insulation Coordination 369
10.5 Propagation of Surges 373
10.6 Determination of System Voltages Produced by Travelling Surges 382
10.7 Electromagnetic Transient Program (EMTP) 391
Problems 399

11 Substations and Protection 403
11.1 Introduction 403
11.2 Switchgear 404
11.3 Qualities Required of Protection 415
11.4 Components of Protective Schemes 416
11.5 Protection Systems 424
11.6 Distance Protection 427
11.7 Unit Protection Schemes 429
11.8 Generator Protection 430
11.9 Transformer Protection 432
11.10 Feeder Protection 435
Problems 439

12 Fundamentals of the Economics of Operation and Planning of Electricity Systems 443
12.1 Economic Operation of Generation Systems 444
12.2 Fundamental Principles of Generation System Planning 451
12.3 Economic Operation of Transmission Systems 457
12.4 Fundamental Principles of Transmission System Planning 460
12.5 Distribution and Transmission Network Security Considerations 463
12.6 Drivers for Change 466
Problems 467

Appendix A Synchronous Machine Reactances 473
Appendix B Typical Transformer Impedances 477
Appendix C Typical Overhead Line Parameters 481

Further Reading 487
Index 491