Table Of ContentAbout the Authors
S Kamakshaiah
S Kamakshaiah is former professor of electrical engineering and head, Department of Electrical Engineering,
College of Engineering, Jawaharlal Nehru Technological University, Hyderabad (A.P.). He completed BE
with honors from Government College of Engineering, Ananathapur in 1962, and obtained ME and PhD
from Indian Institute of Science, Bangalore, in High Voltage Engineering in 1965 and 1977, respectively.
Dr Kamakshaiah has done extensive research in the area of triggered vacuum gaps and has a teaching and
research experience spanning more than 45 years. He has supervised more than 25 MTech and six PhD
theses. To his credit are 25 research papers, published in national and international journals. Among his many
accolades are a Best Theses award for his PhD work and recognition as Best Teacher by the Government
of Andhra Pradesh in 1997. Dr Kamakshaiah has also authored several books in the fi eld of electrical
engineering.
V Kamaraju
V Kamaraju is former professor of electrical engineering and principal, College of Engineering, Jawaharlal
Nehru Technological University, Kakinada (A.P.). He completed BE with honors in 1963 from the same
college, and ME and PhD in High Voltage Engineering from Indian Institute of Science, Bangalore in 1965
and 1978, respectively. Dr Kamaraju has more than 45 years of teaching and research experience. He has
supervised 25 MTech and two PhD theses and to his credit are more than 20 papers published in national
and international journals. He has also been a visiting professor at Middle East Technical University, Turkey.
Dr Kamaraju has erected and commissioned a medium-sized high voltage laboratory at Jawaharlal Nehru
Technological University, College of Engineering, Kakinada. He has been honored as Best Teacher by the
Government of Andhra Pradesh in 2001. He has also authored books on electrical engineering in the past,
includingHigh Voltage Engineering with the late Prof. M S Naidu and Electrical Power Distribution Systems;
both published by Tata McGraw-Hill.
S Kamakshaiah
Formerly Professor and Head of Department
Department of Electrical Engineering
College of Engineering
Jawaharlal Nehru Technological University
Hyderabad, Andhra Pradesh
V Kamaraju
Formerly Professor of Electrical Engineering and Principal
College of Engineering
Jawaharlal Nehru Technological University
Kakinada, Andhra Pradesh
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HVDC Transmission
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RALQCRXCDRRZC
Dedicated to my Almighty
S Kamakshaiah
Dedicated to my Family
V S Rao (son), V Radhika (daughter),
V Rajiv (grandson) and VVSN Jagadeeswari (daughter-in-law)
whose encouragement, patience and help made this book possible.
V Kamaraju
Contents
Foreword xi
Preface xiii
List of Symbols xvii
Abbreviations xix
Inside xx
Chapter One HVDC Transmission: Developments 1
1.1 Introduction 1
1.2 Historical Development 1
1.3 Equipment required for HVDC Systems 13
1.4 Comparison of AC and DC Transmission 17
1.5 Limitations of HVDC Transmission Lines 28
1.6 Reliability of HVDC Systems 28
1.7 Standard Rated Voltages of HVDC and EHVAC Systems 29
1.8 Choice of EHVAC and UHVAC Lines and Substation 30
1.9 Comparison of HVDC Link with EHVAC Link 31
1.10 HVDC-VSC Transmission Systems 31
References 35
Worked Examples 35
Questions 37
Problems 38
Multiple Choice Questions 38
Chapter Two HVDC Converters 40
2.1 Introduction 40
2.2 Thyristors and their Characteristics 40
2.3 Silicon Controlled Rectifi er (SCR) 42
2.4 Insulated Gate Bipolar Transistors (IGBTs) 53
2.5 HVDC Converter Valves and Valve Assembly 57
2.6 HVDC-Voltage Source Converters: Principle and Operation 58
2.7 3-phase 6-pulse Converters using SCRs or Thyristors 62
2.8 12-pulse Bridge Converters 63
References 65
Worked Examples 65
Questions 66
Multiple Choice Questions 66
Chapter Three 6-pulse Converter Operation and Analysis 68
3.1 Introduction 68
3.2 Conduction Sequence in 6-pulse Converter Confi guration 3 68
3.3 The Ideal Commutation Process without Gate Control 70
3.4 DC Output Voltage 71
3.5 Gate Control (Phase Control) of Valves 75
3.6 Analysis of Voltage Waveforms with Overlap Angle (m) 81
viii
Contents
3.7 Voltage Drop in Per Unit Quantities 92
3.8 Complete Characteristics of Converter as Rectifi er/Inverter 94
3.9 Analysis of 12-pulse Converter 100
3.10 Power Flow in HVDC Links 103
3.11 Operation and Analysis of VSC Converters 106
References 112
Worked Examples 112
Questions 123
Problems 125
Multiple Choice Questions 126
Chapter Four Control of HVDC Converter and Systems 129
4.1 Introduction 129
4.2 Mechanism of AC Power Transmission 129
4.3 Principles of Control 130
4.4 Necessity of Control in case of a DC Link 130
4.5 Rectifi er Control 131
4.6 Compounding of Rectifi ers 135
4.7 Power Reversal in a DC Link 139
4.8 Voltage Dependent Current Order Limit (VDCOL)—
Characteristics of the Converter 140
4.9 System Control Hierarchy and Basic Philosophy 142
4.10 Inverter Extinction Angle Control (EAG) 152
4.11 Pulse Phase Control 153
4.12 Starting and Stopping of a DC Link 154
4.13 Constant Power Control 156
4.14 Control Systems for HVDCConverters 156
4.15 Inverter Operation Problems 159
4.16 Control of VSC Converters 162
References 166
Worked Examples 166
Questions 170
Problems 171
Multiple Choice Questions 172
Chapter Five Harmonics in HVDC Systems 174
5.1 Introduction 174
5.2 Importance of Harmonic Study 174
5.3 Generation of Harmonics by Converters 174
5.4 Characteristic Harmonics on the DC Side 178
5.5 Characteristic Current Harmonics 181
5.6 Characteristic Variation of Harmonic Currents with Variation of aandm 187
5.7 Effect of Control Modes on Harmonics 188
5.8 Noncharacteristic Harmonics 189
5.9 Harmonics in VSC Converters 190
References 192
Worked Examples 192
Questions 195
ix
Contents
Problems 195
Multiple Choice Questions 195
Chapter Six Harmonic Suppression in HVDC System—Filters 197
6.1 Introduction 197
6.2 Harmonic Model and Equivalent Circuit 197
6.3 Use of Filters 200
6.4 Filter Confi guration 202
6.5 Design of a Band-Pass Filter 204
6.6 Minimum Cost of Tuned AC Filters 208
6.7 Design of High-Pass Filters 209
6.8 Protection of Filters 209
6.9 Reactive Power Considerations 210
6.10 DC Filters 212
6.11 Power Line Communication and RI Noise 213
6.12 Active Filters and their Applications 213
6.13 Filters with Voltage Source Converter (VSC) HVDC Schemes 215
6.14 Other Methods of Harmonic Elimination 217
References 218
Worked Example 219
Questions 220
Multiple Choice Questions 221
Chapter Seven Grounding and Ground Electrodes for HVDC Systems 223
7.1 Introduction 223
7.2 Advantages and Problems with Ground Return 223
7.3 High Voltage Direct Current Systems—Grounding 225
7.4 The Current Field in the Earth near an Electrode 225
7.5 Resistance of Electrodes—Electric Current Field 227
7.6 Distribution of Current Field between the Electrodes 237
7.7 Natural Current Field due to the Earth’s Magnetic Field 238
7.8 Effect of Ground Return on Buried Objects 238
7.9 Requirements of Electrodes 239
7.10 Basic Parameters of Design of Ground Electrodes 240
7.11 Design of Land Electrodes 248
References 255
Worked Examples 255
Questions 258
Problems 259
Multiple Choice Questions 259
Chapter Eight Faults and Protection Schemes in HVDC Systems 262
8.1 Introduction 262
8.2 Nature and Types of Faults 262
8.3 Faults on AC side of Converter Stations 263
8.4 Converter Faults 265
8.5 Faults on DC side of the System 273
8.6 Protection against Overcurrents/Overvoltages 279
x
Contents
8.7 Protection of Filter Units 280
References 280
Questions 281
Multiple Choice Questions 281
Chapter Nine Overvoltages and Insulation Co-ordination for HVDC Systems 283
9.1 Introduction 283
9.2 Insulators for HVDC Overhead Lines 284
9.3 Lightning Overvoltages 287
9.4 Fast Transient Overvoltages produced by Converters 289
9.5 Overvoltages due to Faults or Disturbances from AC side 290
9.6 Protection against Overvoltages 291
9.7 Insulation Design of DC Lines and Air Clearances 296
9.8 Insulation Co-ordination for Converter Stations and DC Systems 297
References 299
Worked Examples 299
Questions 303
Multiple Choice Questions 303
Chapter Ten Multiterminal HVDC Systems 305
10.1 Introduction 305
10.2 Types of Multiterminal (MTDC) Systems 306
10.3 Parallel Operation Aspects of MTDC 307
10.4 Paralleling (Disconnecting) of Units or Converter 309
10.5 Control of Power in MTDC 309
10.6 VSC—Multilevel DC Systems 311
References 314
Questions 314
Multiple Choice Questions 314
Chapter Eleven Parallel AC and DC Systems 316
11.1 Introduction 316
11.2 Power Transfer Capabilities 316
11.3 Reliability Conditions 317
11.4 Power Loss Considerations and Other Technical Aspects 317
11.5 Environmental Characteristics Considerations for DC Transmission 319
11.6 Power Upgrading and Conversion of AC Lines (Systems) into DC Lines 324
11.7 DC and AC System Interaction 327
11.8 Parallel AC/DC Systems 333
11.9 FACTS and FACT Converters/HVDC 338
11.10 Modelling of HVDC Systems 349
References 354
Questions 355
Multiple Choice Questions 356
Appendix Some HVDC Projects implemented in India 358
Author Index 365
Subject Index 367
