Presents phasor and dynamic analytical models f
Table of Contents
Contents
Preface xi
Part I HVDC with Current Source Converters 1
1 Introduction to Line-Commutated HVDC 3
1.1 HVDC Applications 3
1.2 Line-Commutated HVDC Components 5
1.3 DC Cables and Overhead Lines 6
1.4 LCC HVDC Topologies 7
1.5 Losses in LCC HVDC Systems 9
1.6 Conversion of AC Lines to DC 10
1.7 Ultra-High Voltage HVDC 10
2 Thyristors 12
2.1 Operating Characteristics 12
2.2 Switching Characteristic 13
2.3 Losses in HVDC Thyristors 17
2.4 Valve Structure and Thyristor Snubbers 20
2.5 Thyristor Rating Selection and Overload Capability 22
3 Six-Pulse Diode and Thyristor Converter 23
3.1 Three-Phase Uncontrolled Bridge 23
3.2 Three-Phase Thyristor Rectifier 25
3.3 Analysis of Commutation Overlap in a Thyristor Converter 26
3.4 Active and Reactive Power in a Three-Phase Thyristor Converter 30
3.5 Inverter Operation 31
4 HVDC Rectifier Station Modelling, Control and Synchronization with AC Systems 35
4.1 HVDC Rectifier Controller 35
4.2 Phase-Locked Loop (PLL) 36
5 HVDC Inverter Station Modelling and Control 40
5.1 Inverter Controller 40
5.2 Commutation Failure 42
6 HVDC System V-I Diagrams and Operating Modes 45
6.1 HVDC-Equivalent Circuit 45
6.2 HVDC V-I Operating Diagram 45
6.3 HVDC Power Reversal 48
7 HVDC Analytical Modelling and Stability 53
7.1 Introduction to Converters and HVDC Modelling 53
7.2 HVDC Analytical Model 54
7.3 CIGRE HVDC Benchmark Model 56
7.4 Converter Modelling, Linearization and Gain Scheduling 56
7.5 AC System Modelling for HVDC Stability Studies 58
7.6 LCC Converter Transformer Model 62
7.7 DC System Model 63
7.8 HVDC-HVAC System Model 65
7.9 Analytical Dynamic Model Verification 65
7.10 Basic HVDC Dynamic Analysis 66
7.11 HVDC Second Harmonic Instability 70
7.12 Oscillations of 100 Hz on the DC Side 71
8 HVDC Phasor Modelling and Interactions with AC System 72
8.1 Converter and DC System Phasor Model 72
8.2 Phasor AC System Model and Interaction with the DC System 73
8.3 Inverter AC Voltage and Power Profile as DC Current is Increasing 75
8.4 Influence of Converter Extinction Angle 76
8.5 Influence of Shunt Reactive Power Compensation 78
8.6 Influence of Load at the Converter Terminals 78
8.7 Influence of Operating Mode (DC Voltage Control Mode) 78
8.8 Rectifier Operating Mode 80
9 HVDC Operation with Weak AC Systems 82
9.1 Introduction 82
9.2 Short-Circuit Ratio and Equivalent Short-Circuit Ratio 82
9.3 Power Transfer between Two AC Systems 85
9.4 Phasor Study of Converter Interactions with Weak AC Systems 89
9.5 System Dynamics (Small Signal Stability) with Low SCR 90
9.6 Control and Main Circuit Solutions for Weak AC Grids 90
9.7 LCC HVDC with SVC (Static VAR Compensator) 91
9.8 Capacitor-Commutated Converters for HVDC 93
9.9 AC System with Low Inertia 93
10 Fault Management and HVDC System Protection 98
10.1 Introduction 98
10.2 DC Line Faults 98
10.3 AC System Faults 101
10.4 System Reconfiguration for Permanent DC Faults 103
10.5 Overvoltage Protection 106
11 LCC HVDC System Harmonics 107
11.1 Harmonic Performance Criteria 107
11.2 Harmonic Limits 108
11.3 Thyristor Converter Harmonics 109
11.4 Harmonic Filters 110
11.5 Noncharacteristic Harmonic Reduction Using HVDC Controls 118
Bibliography Part I Line Commutated Converter HVDC 119
Part II HVDC with Voltage Source Converters 121
12 VSC HVDC Applications and Topologies, Performance and Cost Comparison with LCC HVDC 123
12.1 Voltage Source Converters (VSC) 123
12.2 Comparison with Line-Commutated Converter (LCC) HVDC 125
12.3 Overhead and Subsea/Underground VSC HVDC Transmission 126
12.4 DC Cable Types with VSC HVDC 129
12.5 Monopolar and Bipolar VSC HVDC Systems 129
12.6 VSC HVDC Converter Topologies 130
12.7 VSC HVDC Station Components 135
12.8 AC Reactors 139
12.9 DC Reactors 139
13 IGBT Switches and VSC Converter Losses 141
13.1 Introduction to IGBT and IGCT 141
13.2 General VSC Converter Switch Requirements 142
13.3 IGBT Technology 142
13.4 Development of High Power IGBT Devices 147
13.5 IEGT Technology 148
13.6 Losses Calculation 148
13.7 Balancing Challenges in Series IGBT Chains 154
13.8 Snubbers Circuits 155
14 Single-Phase and Three-Phase Two-Level VSC Converters 156
14.1 Introduction 156
14.2 Single-Phase Voltage Source Converter 156
14.3 Three-Phase Voltage Source Converter 159
14.4 Square-Wave, Six-Pulse Operation 159
15 Two-Level PWM VSC Converters 167
15.1 Introduction 167
15.2 PWM Modulation 167
15.3 Sinusoidal Pulse-Width Modulation (SPWM) 168
15.4 Third Harmonic Injection (THI) 171
15.5 Selective Harmonic Elimination Modulation (SHE) 172
15.6 Converter Losses for Two-Level SPWM VSC 173
15.7 Harmonics with Pulse-Width Modulation (PWM) 175
15.8 Comparison of PWM Modulation Techniques 178
16 Multilevel VSC Converters 180
16.1 Introduction 180
16.2 Modulation Techniques for Multilevel Converters 182
16.3 Neutral Point Clamped Multilevel Converter 183
16.4 Flying Capacitor Multilevel Converter 185
16.5 H-Bridge Cascaded Converter 186
16.6 Half Bridge Modular Multilevel Converter (MMC) 187
16.7 MMC Based on Full Bridge Topology 200
16.8 Comparison of Multilevel Topologies 208
17 Two-Level PWM VSC HVDC Modelling, Control and Dynamics 209
17.1 PWM Two-Level Converter Average Model 209
17.2 Two-Level PWM Converter Model in DQ Frame 210
17.3 VSC Converter Transformer Model 212
17.4 Two-Level VSC Converter and AC Grid Model in ABC Frame 213
17.5 Two-Level VSC Converter and AC Grid Model in DQ Rotating Coordinate Frame 213
17.6 VSC Converter Control Principles 214
17.7 The Inner Current Controller Design 215
17.8 Outer Controller Design 218
17.9 Complete VSC Converter Controller 221
17.10 Small-Signal Linearized VSC HVDC Model 224
17.11 Small-Signal Dynamic Studies 224
18 Two-Level VSC HVDC Phasor-Domain Interaction with AC Systems and PQ Operating Diagrams 226
18.1 Power Exchange between Two AC Voltage Sources 226
18.2 Converter Phasor Model and Power Exchange with an AC System 230
18.3 Phasor Study of VSC Converter Interaction with AC System 232
18.4 Operating Limits 234
18.5 Design Point Selection 236
18.6 Influence of AC System Strength 239
18.7 Influence of Transformer Reactance 243
18.8 Operation with Very Weak AC Systems 247
19 Half Bridge MMC Converter: Modelling, Control and Operating PQ Diagrams 254
19.1 Half Bridge MMC Converter Average Model in ABC Frame 254
19.2 Half-Bridge MMC Converter-Static DQ Frame and Phasor Model 257
19.3 Differential Current at Second Harmonic 262
19.4 Complete MMC Converter DQ Model in Matrix Form 263
19.5 Second Harmonic Circulating Current Suppression Controller 264
19.6 DQ Frame Model of MMC with Circulating Current Controller 267
19.7 Phasor Model of MMC with Circulating Current Suppression Controller 269
19.8 Dynamic MMC Model Using Equivalent Series Capacitor CMMC 270
19.9 Full Dynamic Analytical MMC Model 273
19.10 MMC Converter Controller 275
19.11 MMC Total Series Reactance in the Phasor Model 275
19.12 MMC VSC Interaction with AC System and PQ Operating Diagrams 277
20 VSC HVDC under AC and DC Fault Conditions 280
20.1 Introduction 280
20.2 Faults on the AC System 280
20.3 DC Faults with Two-Level VSC 281
20.4 Influence of DC Capacitors 286
20.5 VSC Converter Modelling under DC Faults and VSC Diode Bridge 287
20.6 Converter-Mode Transitions as DC Voltage Reduces 294
20.7 DC Faults with Half-Bridge Modular Multilevel Converter 294
20.8 DC Faults with Full-Bridge Modular Multilevel Converter 298
21 VSC HVDC Application for AC Grid Support and Operation with Passive AC Systems 302
21.1 VSC HVDC High-Level Controls and AC Grid Support 302
21.2 HVDC Embedded inside an AC Grid 303
21.3 HVDC Connecting Two Separate AC Grids 304
21.4 HVDC in Parallel with AC 304
21.5 Operation with a Passive AC System and Black Start Capability 305
21.6 VSC HVDC Operation with Offshore Wind Farms 305
21.7 VSC HVDC Supplying Power Offshore and Driving a MW-Size Variable-Speed Motor 307
Bibliography Part II Voltage Source Converter HVDC 309
Part III DC Transmission Grids 311
22 Introduction to DC Grids 313
22.1 DC versus AC Transmission 313
22.2 Terminology 314
22.3 DC Grid Planning, Topology and Power-Transfer Security 314
22.4 Technical Challenges 315
22.5 DC Grid Building by Multiple Manufacturers 316
22.6 Economic Aspects 316
23 DC Grids with Line-Commutated Converters 317
23.1 Multiterminal HVDC 317
23.2 Italy–Corsica–Sardinia Multiterminal HVDC Link 318
23.3 Connecting LCC Converter to a DC Grid 319
23.4 Control of LCC Converters in DC Grids 321
23.5 Control of LCC DC Grids through DC Voltage Droop Feedback 321
23.6 Managing LCC DC Grid Faults 323
23.7 Reactive Power Issues 325
23.8 Large LCC Rectifier Stations in DC Grids 325
24 DC Grids with Voltage Source Converters and Power-Flow Model 326
24.1 Connecting a VSC Converter to a DC Grid 326
24.2 DC Grid Power Flow Model 327
24.3 DC Grid Power Flow under DC Faults 331
25 DC Grid Control 334
25.1 Introduction 334
25.2 Fast Local VSC Converter Control in DC Grids 334
25.3 DC Grid Dispatcher with Remote Communication 336
25.4 Primary, Secondary and Tertiary DC Grid Control 337
25.5 DC Voltage Droop Control for VSC Converters in DC Grids 338
25.6 Three-Level Control for VSC Converters with Dispatcher Droop 339
25.7 Power Flow Algorithm When DC Powers are Regulated 340
25.8 Power Flow and Control Study of CIGRE DC Grid-Test System 344
26 DC Grid Fault Management and DC Circuit Breakers 349
26.1 Introduction 349
26.2 Fault Current Components in DC Grids 350
26.3 DC System Protection Coordination with AC System Protection 352
26.4 Mechanical DC Circuit Breaker 352
26.5 Semiconductor Based DC Circuit Breaker 355
26.6 Hybrid DC Circuit Breaker 359
26.7 DC Grid-Protection System Development 361
26.8 DC Grid Selective Protection System Based on Current Derivative or Travelling Wave Identification 362
26.9 Differential DC Grid Protection Strategy 363
26.10 DC Grid Selective Protection System Based on Local Signals 364
26.11 DC Grids with DC Fault-Tolerant VSC Converters 365
27 High Power DC/DC Converters and DC Power-Flow Controlling Devices 372
27.1 Introduction 372
27.2 Power Flow Control Using Series Resistors 373
27.3 Low Stepping-Ratio DC/DC Converters 376
27.4 High Stepping Ratio Isolated DC/DC Converter 383
27.5 High Stepping Ratio LCL DC/DC Converter 383
27.6 Building DC Grids with DC/DC Converters 385
27.7 DC Hubs 387
27.8 Developing DC Grids Using DC Hubs 390
27.9 North Sea DC Grid Topologies 390
Bibliography Part III DC Transmission Grids 394
Appendix A Variable Notations 396
Appendix B Analytical Background for Rotating DQ Frame 398
Appendix C System Modelling Using Complex Numbers and Phasors 409
Appendix D Simulink Examples 411
Index 000
