HVDC Grids E-Book

Dirk Van Hertem

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: IEEE Press Series on Power Engineering
• Sprache: Englisch

Seitenzahl: 824

Veröffentlichungsjahr: 2016

Beschreibung

This book discusses HVDC grids based on multi-terminal voltage-source converters (VSC), which is suitable for the connection of offshore wind farms and a possible solution for a continent wide overlay grid. HVDC Grids: For Offshore and Supergrid of the Future begins by introducing and analyzing the motivations and energy policy drives for developing offshore grids and the European Supergrid. HVDC transmission technology and offshore equipment are described in the second part of the book. The third part of the book discusses how HVDC grids can be developed and integrated in the existing power system. The fourth part of the book focuses on HVDC grid integration, in studies, for different time domains of electric power systems. The book concludes by discussing developments of advanced control methods and control devices for enabling DC grids. * Presents the technology of the future offshore and HVDC grid * Explains how offshore and HVDC grids can be integrated in the existing power system * Provides the required models to analyse the different time domains of power system studies: from steady-state to electromagnetic transients This book is intended for power system engineers and academics with an interest in HVDC or power systems, and policy makers. The book also provides a solid background for researchers working with VSC-HVDC technologies, power electronic devices, offshore wind farm integration, and DC grid protection.

Leseprobe

IEEE Press

445 Hoes Lane

Piscataway, NJ 08854

IEEE Press Editorial Board

Tariq Samad, Editor in Chief

George W. Arnold

Xiaoou Li

Ray Perez

Giancarlo Fortino

Vladimir Lumelsky

Linda Shafer

Dmitry Goldgof

Pui-In Mak

Zidong Wang

Ekram Hossain

Jeffrey Nanzer

MengChu Zhou

Kenneth Moore, Director of IEEE Book and Information Services (BIS)

Technical Reviewer

Dragan Jovcic, University of Aberdeen

HVDC GRIDS

For Offshore and Supergrid of the Future

Edited by

DIRK VAN HERTEM ORIOL GOMIS-BELLMUNT JUN LIANG

Copyright © 2016 by The Institute of Electrical and Electronics Engineers, Inc.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey. All rights reserved. Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, [phone], fax [phone], or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, [phone], fax [phone], or online at http://www.wiley.com/go/permission.

Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.

For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at [phone], outside the United States at [phone] or fax [phone].

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com.

Library of Congress Cataloging-in-Publication Data is available.

ISBN: 978-1-118-85915-5

To Els, Elena, Sílvia, Clara,

Rita, Chunmei, Qianyun,

our wives and daughters,

for keeping us onshore

and connected to ground

CONTENTS

CONTRIBUTORS

FOREWORD

PREFACE

ACKNOWLEDGMENTS

ACRONYMS

PART

I

HVDC GRIDS IN THE ENERGY VISION OF THE FUTURE

CHAPTER 1

DRIVERS FOR THE DEVELOPMENT OF HVDC GRIDS

1.1 INTRODUCTION

1.2 FROM THE VERTICALLY INTEGRATED INDUSTRY TO FAST MOVING LIBERALIZED MARKET

1.3 DRIVERS FOR CHANGE

1.4 INVESTMENTS IN THE GRID

1.5 TOWARDS HVDC GRIDS

1.6 CONCLUSIONS

REFERENCES

NOTES

CHAPTER 2

ENERGY SCENARIOS: PROJECTIONS ON EUROPE’S FUTURE GENERATION AND LOAD:

2.1 INTRODUCTION

2.2 SYSTEM SETTING

2.3 SCENARIOS FOR EUROPE’S ENERGY PROVISION

2.4 CONCLUSIONS

REFERENCES

PART

II

HVDC TECHNOLOGY AND TECHNOLOGY FOR OFFSHORE GRIDS

CHAPTER 3

HVDC TECHNOLOGY OVERVIEW

3.1 INTRODUCTION

3.2 LCC-HVDC SYSTEMS

3.3 LCC-HVDC CONVERTER STATION TECHNOLOGY

3.4 VSC-HVDC SYSTEMS

3.5 VSC-HVDC CONVERTER STATION TECHNOLOGY

3.6 TRANSMISSION LINES

3.7 CONCLUSIONS

REFERENCES

CHAPTER 4

COMPARISON OF HVAC AND HVDC TECHNOLOGIES

4.1 INTRODUCTION

4.2 CURRENT TECHNOLOGY LIMITS

4.3 TECHNICAL COMPARISON

4.4 ECONOMIC COMPARISON

4.5 CONCLUSIONS

REFERENCES

NOTES

CHAPTER 5

WIND TURBINE TECHNOLOGIES

5.1 INTRODUCTION

5.2 PARTS OF THE WIND TURBINE

5.3 WIND TURBINE TYPES

5.4 CONCLUSIONS

REFERENCES

CHAPTER 6

OFFSHORE WIND POWER PLANTS (OWPPS)

6.1 INTRODUCTION

6.2 AC OWPPs

6.3 DC OWPPs

6.4 Other OWPPs Proposals

6.5 CONCLUSIONS

REFERENCES

PART

III

PLANNING AND OPERATION OF HVDC GRIDS

CHAPTER 7

HVDC GRID PLANNING

7.1 CONTEXT OF TRANSMISSION SYSTEM PLANNING

7.2 TRANSMISSION EXPANSION OPTIMIZATION METHODOLOGIES

7.3 SPECIALTIES OF GRID PLANNING WITH HVDC TECHNOLOGY

7.4 ILLUSTRATIVE EXAMPLES

REFERENCES

CHAPTER 8

HVDC GRID LAYOUTS

8.1 WHAT IS AN HVDC GRID?

8.2 HVDC GRID TOPOLOGIES

8.3 TOPOLOGIES OF HVDC GRIDS FOR OFFSHORE WIND POWER TRANSMISSION

8.4 HVDC CONVERTER STATION CONFIGURATION

8.5 SUBSTATION CONFIGURATION

8.6 CONCLUSIONS

REFERENCES

NOTE

CHAPTER 9

GOVERNANCE MODELS FOR FUTURE GRIDS

9.1 INTRODUCTION

9.2 TRANSMISSION GRID PLANNING

9.3 TRANSMISSION GRID OWNERSHIP

9.4 TRANSMISSION GRID FINANCING

9.5 TRANSMISSION GRID PRICING

9.6 TRANSMISSION GRID OPERATION

9.7 CONCLUSIONS

REFERENCES

CHAPTER 10

POWER SYSTEM OPERATIONS WITH HVDC GRIDS

10.1 INTRODUCTION

10.2 WHO OPERATES THE HVDC LINK OR GRID?

10.3 RELIABILITY CONSIDERATIONS IN SYSTEMS WITH HVDC

10.4 MANAGING ENERGY UNBALANCES IN THE SYSTEM

10.5 ACTIVE AND REACTIVE POWER CONTROL

10.6 ANCILLARY SERVICES

10.7 GRID CODES

10.8 CONCLUSIONS

REFERENCES

NOTES

CHAPTER 11

OPERATION AND CONTROL OF OFFSHORE WIND POWER PLANTS

11.1 INTRODUCTION

11.2 SYSTEM UNDER ANALYSIS

11.3 CONTROL AND PROTECTION REQUIREMENTS

11.4 WIND POWER PLANT CONTROL STRUCTURE

11.5 DYNAMIC SIMULATION OF A SIMPLIFIED EXAMPLE

11.6 CONCLUSIONS

REFERENCES

NOTES

PART

IV

MODELING HVDC GRIDS

CHAPTER 12

MODELS FOR HVDC GRIDS

12.1 INTRODUCTION

12.2 POWER SYSTEM COMPUTATION PROGRAMS

12.3 MODELING POWER ELECTRONIC CONVERTERS

12.4 HVDC GRIDS MODELING CHALLENGES

12.5 CONCLUSIONS

REFERENCES

CHAPTER 13

POWER FLOW MODELING OF HYBRID AC/DC SYSTEMS

13.1 INTRODUCTION

13.2 SIMPLIFIED POWER FLOW MODELING

13.3 DETAILED POWER FLOW MODELING

13.4 SEQUENTIAL AC/DC POWER FLOW

13.5 SOFTWARE IMPLEMENTATION

13.6 TEST CASE

13.7 CONCLUSIONS

REFERENCES

NOTES

CHAPTER 14

OPTIMAL POWER FLOW MODELING OF HYBRID AC/DC SYSTEMS

14.1 INTRODUCTION

14.2 OPTIMAL POWER FLOW: STANDARD FORMULATION AND EXTENSION

14.3 OPTIMAL POWER FLOW WITH DC GRIDS AND CONVERTERS

14.4 ADDING SECURITY CONSTRAINTS

14.5 CONCLUSIONS

REFERENCES

NOTE

CHAPTER 15

CONTROL PRINCIPLES OF HVDC GRIDS

15.1 INTRODUCTION

15.2 BASIC CONTROL PRINCIPLES

15.3 BASIC CONVERTER CONTROL STRATEGIES

15.4 ADVANCED CONVERTER CONTROL STRATEGIES

15.5 BASIC GRID CONTROL STRATEGIES

15.6 ADVANCED GRID CONTROL STRATEGIES

15.7 CONVERTER INNER CURRENT CONTROL

15.8 SYSTEM POWER FLOW CONTROL

15.9 CONCLUSIONS

REFERENCES

NOTES

CHAPTER 16

STATE-SPACE REPRESENTATION OF HVDC GRIDS

16.1 INTRODUCTION

16.2 MULTI-TERMINAL GRID MODELING

16.3 FOUR-TERMINAL GRID EXAMPLE

16.4 CONCLUSIONS

REFERENCES

CHAPTER 17

DC FAULT PHENOMENA AND DC GRID PROTECTION

17.1 INTRODUCTION

17.2 SHORT-CIRCUIT FAULTS IN THE DC GRID

17.3 DC GRID PROTECTION

17.4 DC PROTECTION COMPONENTS

17.5 CONCLUSIONS

REFERENCES

CHAPTER 18

REAL-TIME SIMULATION EXPERIMENTS OF DC GRIDS

18.1 INTRODUCTION

18.2 REAL-TIME SIMULATION IN POWER SYSTEMS

18.3 DESIGN OF EXPERIMENTAL TEST RIG

18.4 POTENTIAL APPLICATIONS OF HIL TESTS IN DC GRIDS

REFERENCES

PART

V

APPLICATIONS

CHAPTER 19

POWER SYSTEM OSCILLATION DAMPING BY MEANS OF VSC-HVDC SYSTEMS

19.1 INTRODUCTION

19.2 POWER SYSTEM STABILITY

19.3 VSC-HVDC SYSTEMS DAMPING CONTRIBUTION: APPLICATION EXAMPLES

19.4 CONCLUSIONS

REFERENCES

CHAPTER 20

OPTIMAL DROOP CONTROL OF MULTI-TERMINAL VSC-HVDC GRIDS

20.1 INTRODUCTION

20.2 CONTROL OF MULTI-TERMINAL VSC-HVDC GRIDS

20.3 TIME-VARYING DESCRIPTION FOR DROOP CONTROL DESIGN

20.4 DESIGN OF OPTIMAL CONTROL DROOPS

20.5 FOUR-TERMINAL VSC-HVDC NETWORK EXAMPLE

20.6 CONCLUSIONS

REFERENCES

NOTES

CHAPTER 21

DC GRID POWER FLOW CONTROL DEVICES

21.1 DC POWER FLOW CONTROL DEVICES (DCPFC)

21.2 GENERIC MODELING OF DC POWER FLOW CONTROL DEVICES

21.3 SENSITIVITY ANALYSIS OF DCPFC IN DC GRID

21.4 CASE STUDY OF POWER FLOW CONTROL DEVICES IN DC GRIDS

21.5 CONTROL SENSITIVITY OF DCPFC IN DC GRIDS

21.6 COMPARISON OF POWER CONTROL DEVICES

21.7 CONCLUSIONS

REFERENCES

CHAPTER 22

MODELING AND CONTROL OF OFFSHORE AC HUB

22.1 REASONS FOR DEVELOPING AC HUB

22.2 WHAT IS THE AC HUB?

22.3 FREQUENCY-DEPENDENT MODELING OF AC HUB COMPONENTS

22.4 AC HUB CONTROL USING VARIABLE FREQUENCY

22.5 CONCLUSIONS

REFERENCES

INDEX

IEEE Press Series on Power Engineering

EULA

List of Tables

Chapter 2

Table 2.1

Table 2.2

Table 2.3

Table 2.4

Chapter 3

Table 3.1

Table 3.2

Chapter 4

Table 4.1

Table 4.2

Table 4.3

Table 4.4

Table 4.5

Table 4.6

Table 4.7

Table 4.8

Chapter 6

Table 6.1

Table 6.2

Chapter 7

Table 7.1

Table 7.2

Table 7.3

Table 7.4

Chapter 8

Table 8.1

Chapter 9

Table 9.1

Table 9.2

Chapter 13

Table 13.1

Chapter 14

Table 14.1

Table 14.2

Table 14.3

Table 14.4

Chapter 16

Table 16.1

Table 16.2

Chapter 17

Table 17.1

Table 17.2

Table 17.3

Table 17.4

Table 17.5

Chapter 18

Table 18.1

Table 18.2

Table 18.3

Table 18.4

Table 18.5

Table 18.6

Table 18.7

Chapter 20

Table 20.1

Chapter 21

Table 21.1

Table 21.2

Table 21.3

Table 21.4

Table 21.5

Chapter 22

Table 22.1

Table 22.2

Table 22.3

Guide

Cover

Table of Contents

Preface

Pages

xxvii

xxviii

xxix

xxx

xxxi

xxxii

xxxiii

xxxiv

xxxv

xxxvii

xxxviii

xxxix

xl

1

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

45

46

47

48

49

50

51

52

53

56

57

58

60

61

62

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

210

211

212

213

214

215

216

217

218

219

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

239

240

241

242

243

244

245

246

247

248

249

254

255

256

257

258

259

260

261

262

263

264

265

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

345

346

347

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

391

392

393

394

395

396

397

398

399

400

401

402

403

405

406

407

408

409

410

411

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

429

430

431

432

433

434

435

436

437

438

439

440

441

443

444

445

446

447

448

449

450

451

452

453

454

455

457

458

459

460

462

463

464

465

466

467

468

469

470

471

473

474

475

476

477

478

479

480

481

483

484

485

486

CONTRIBUTORS

OLUWOLE DANIEL ADEUYI   Institute of Energy, School of Engineering, Cardiff University, Cardiff, Wales

MONICA ARAGUES PENALBA,   Research Group CITCEA, Electrical Engineering Department, Technical University of Catalonia (UPC), Barcelona, Spain

JEF BEERTEN   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

FERNANDO D. BIANCHI   Research Group Wind Energy, Electrical Engineering Department, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

MARC CHEAH,   Institute of Energy, School of Engineering, Cardiff University, Cardiff, Wales

CEDRIC DE JONGHE   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

MIKEL DE PRADA-GIL   Research Group Wind Energy, Electrical Engineering Department, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

KRISTOF DE VOS   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

ERIK DELARUE   Research Group TME, Department of Mechanical Engineering, University of Leuven, Leuven, Belgium

FRANCISCO DIAZ GONZALEZ   Electrical Engineering Department, Technical University of Catalonia (UPC), Barcelona, Spain

JOSE LUIS DOMINGUEZ GARCIA   Research Group Wind Energy, Electrical Engineering Department, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

AGUSI EGEA   Research Group CITCEA, Electrical Engineering Department, Technical University of Catalonia (UPC), Barcelona, Spain

HAKAN ERGUN   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

CHUNMEI FENG   Engineering Department, Power Conversion, GE Energy Management, Stoke-on-Trent, United Kingdom

ORIOL GOMIS-BELLMUNT   Research Group CITCEA, Electrical Engineering Department, Technical University of Catalonia (UPC), Barcelona, Spain; and Research Group Wind Energy, Electrical Engineering Department, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

XIAOBO HU   Power System Department, China Electric Power Research Institute (CEPRI), Bejing, China

DIYUN HUANG   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

WILLEM LETERME   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

CHUANYUE LI   Institute of Energy, School of Engineering, Cardiff University, Cardiff, Wales

GEN LI   Institute of Energy, School of Engineering, Cardiff University, Cardiff, Wales

JUN LIANG   Institute of Energy, School of Engineering, Cardiff University, Cardiff, Wales

QING MU   Power System Department, China Electric Power Research Institute (CEPRI), Beijing, China

EDUARDO PRIETO-ARAUJO   Research Group CITCEA, Electrical Engineering Department, Technical University of Catalonia (UPC), Barcelona, Spain

ROBERT H. RENNER   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

JOHAN RIMEZ   Division TGX, Elia Engineering, Brussel, Belgium

ANDREAS SUMPER   Research Group Wind Energy, Electrical Engineering Department, Catalonia Institute for Energy Research (IREC), Barcelona, Spain; and Research Group CITCEA, Electrical Engineering Department, Technical University of Catalonia (UPC), Barcelona, Spain

MUHAJIR TADESSE MEKONNEN   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

CARLOS E. UGALDE LOO   Institute of Energy, School of Engineering, Cardiff University, Cardiff, Wales

DIRK VAN HERTEM   Research Group Electa, Department of Electrical Engineering, University of Leuven, Leuven, Belgium

TIL KRISTIAN VRANA   Norwegian University of Science and Technology, Trondheim, Norway

FOREWORD

Dear Reader,

The present book is one of the first and most significant studies on the concept of a European electricity Supergrid. The editors’ work fills the scientific vacuum in this area. It is very much welcome!

The concept of an electricity Supergrid is now a well-routed expression in the sector, especially in Europe. However, clear definitions are still lacking, and one of the merits of this book is to tackle this. The notion of “Supergrid” has embraced various concepts. I would believe that it is correct to say that initially the Supergrid was limited to that part of the offshore grid which could—potentially—interconnect offshore wind farms located in the North and Baltic Seas. Gradually, the concept was enlarged in order to encompass all of Europe and now represents the very high voltage grid which would be needed to enable the transmission of significant volumes of renewables from where they would be produced to their consumption points. What is meant by “very high voltage” is at this very moment still not precisely defined as are the technical details of the needed technical equipment HVDC and/or others. Again, as mentioned, this work addresses many of these matters.

Today, we can affirm that (almost) nobody really opposes the need to build as soon as possible additional transmission infrastructure in Europe and that the “Supergrid” must become an essential part of that new transmission infrastructure.

The technical challenges are still numerous, but they are not the only ones. Financing the needed infrastructure is definitely another important challenge. The amounts needed to fund the infrastructure are not counted in the millions but in the hundreds of billions. Of course, transmission infrastructure is highly regarded by long-term investors, especially when the investment occurs in a regulated environment. Unfortunately, when one looks closer to the different regulatory regimes currently applicable in the 28 European countries, one will observe that, for the same kind of assets, the rate of returns approved by the respective authorities do greatly vary and could lead to forum shopping by investors, which will make the development of an Energy Union in Europe unfortunately more remote or at least more difficult. We believe it is urgent that Europe looks efficiently into the implementation of, at least, a harmonized regulatory system which will not only provide an attractive investment proposal but will also accelerate the development and construction of the infrastructure as well as foster Europe’s security of supply.

Infrastructure, including high-voltage grids, can only be developed and built inasmuch as the developers have obtained the numerous environmental and other permits prior to construction. When it comes to supra-national infrastructure as is the Supergrid, the developers have to abide by the permitting laws and regulations in several countries. The rights protected by these permits as their respective procedures are more or less similar everywhere in Europe. However, the developer still needs to go country by country. Europe is certainly not (yet…) “lawyer-land” as is the United States of America, but everybody will agree that legal proceedings related to permits can and do take a lot of time (7 to 10 years is definitively not an exception, unfortunately!). This needs to be solved if one wants Europe to become less dependent on foreign energy sources.

The 2013 Electricity Infrastructure Regulation wants the Member States of the European Union to offer a “one-stop shop” body handling the various national permits. This is a strong indicator of Europe’s will to try to clean up this situation without, however, limiting or reducing the individual rights of the European citizens. This initiative is mostly welcome and we hope that the Member States which today are trailing behind regarding for the implementation of this “one-stop shop” body will soon take the necessary steps to comply with this important European Regulation.

Even though permitting remains principally a national competence, we wonder if it would not make sense for Europe to think about an efficient and pragmatic way to have a “European One-Stop Shop” for essential infrastructure having a cross-border impact. A breakthrough herein would certainly significantly reduce the time but also the cost for new infrastructure in Europe.

It is now time to let you, dear Reader, dive into the important work of professors Van Hertem, Gomis-Bellmunt, and Liang and to hope that you too, once you will have been through this book, will definitely be a fan of the European electricity Supergrid!

Enjoy the read.

Pierre Bernard

Chairman of the Board of Friends of the Supergrid

PREFACE

THE FIRST electricity transmission line in the world was a DC line which was built in 1882. Since Westinghouse and Tesla won the “War of Currents” against Edison in the 1890s, AC technology has dominated the electric power transmission. However, DC transmission has enjoyed a revival since the middle of the twentieth century and, so far, more than 200 high-voltage DC (HVDC) projects have been built around the world and offer efficient transmission of large amounts of power over long distances. In the past couple of years, development of DC transmission has gained significant momentum as a result of two key drivers: firstly, the development of modern conversion technology (voltage source converter) and secondly, the need for transmission of offshore wind power. Plans for the interconnection of multiple renewable power sources, loads, and AC grids through DC technologies are leading to an exciting transmission concept: HVDC grids. HVDC grids and supergrids have sparked so much interest that researchers and engineers across the globe are talking about them, studying them, supporting them, or questioning them.

The editors of this book and their research teams have been carrying out extensive and collaborative research on HVDC grids for offshore wind power transmission and have achieved a series of outcomes. It is the editors’ motivation to share their understanding and vision of HVDC grids. It is also the editors’ privilege and responsibility to present a complete picture of HVDC grid technologies by collecting and summarizing recent technological advances, academic research development, and engineering applications.

The objectives of this book are to answer why HVDC is favorable over AC technologies for power transmission; what the key technologies and challenges are for developing an HVDC grid; how an HVDC grid will be designed and operated; and how future HVDC grids will evolve. The book also devotes significant attention to nontechnical aspects such as the influence of energy policy and regulatory frameworks. As such, this book is the first to discuss all relevant topics within the scope of HVDC for offshore grids and the supergrid. It provides valuable information for researchers, industry, and policy makers.

There are 5 parts in this book consisting of 22 chapters.

Part I, “HVDC Grids in the Energy Vision of the Future,” discusses the reasons for and the necessity of building HVDC grids from the viewpoint of energy development and supply. There are two chapters in this part.

Chapter 1: Describes the motivations for developing new transmission infrastructure, including HVDC grids. Clean, cheap, and secure energy supply is a policy goal that drives grid development, requiring new transmission infrastructure. The development of offshore grids and of a supergrid will produce such a closely interconnected energy system.

Chapter 2: Elaborates on the basis of the transmission of electrical energy: generation and demand, and their evolution. The energy balance between supply and demand is emphasized, and its implication toward the DC grid development are investigated. Some future scenarios for the European energy mix are summarized.

Part II, “HVDC Technology and Technology for Offshore Grids,” discusses two of the main technologies for future HVDC grids: HVDC and offshore wind power technologies. These are the foundations which will steer the management, operation, and control of HVDC grids. There are four chapters in this part.

Chapter 3: Gives an overview of both conventional LCC HVDC and newly emerging VSC HVDC technologies. The components of these HVDC technologies are analyzed. The benefits of VSC HVDC over LCC technology for grids are emphasized.

Chapter 4: Gives comprehensive technical and economic comparison between HVAC and HVDC transmission, indicating the advantages of HVDC over traditional HVAC.

Chapter 5: Briefly summarizes the wind turbine technology, with fixed-speed and variable-speed wind turbines.

Chapter 6: Discusses offshore wind power plants using AC or DC collection and transmission technologies.

From Part III, “Planning and Operation of HVDC Grids,” readers can expect to learn how an HVDC grid will be planned, designed, regulated, operated, and controlled. There are five chapters in this part.

Chapter 7: Focuses on the planning of HVDC grids. It provides answers for the four “W” questions on HVDC grid planning—that is, Where, What, When, and Who to invest HVDC grids. Design methods for HVDC grid expansion are also given in this chapter.

Chapter 8: Presents possible layouts of HVDC grids which can be designed in future. This chapter starts from HVDC substation configurations, to VSC pole and grounding configurations and extension, and to the network topologies of HVDC grids. Analyses of topologies particular suitable for offshore HVDC grids are also given.

Chapter 9: Discusses governance issues with national and transnational systems. Ownership, financing, and tariffs of such HVDC grids are described.

Chapter 10: Gives the operation and control principles for future HVDC grids, specifically looking at the interface with AC systems.

Chapter 11: Gives more specific operation and control methods for offshore wind power plants which are connected to HVDC links and HVDC grids.

Part IV, “Modeling HVDC Grids,” presents models and modeling requirements of HVDC grids under various time frames for the purposes of power flow calculation, control design, protection, and system validation. There are seven chapters in this part.

Chapter 12: Defines different time frames for the modeling of HVDC grids for different applications. The objective is to highlight the need for different models within power system analysis and to indicate the specifics of HVDC grids with respect to modeling. The models themselves are introduced in greater detail in Chapters 13 to 18.

Chapter 13: Power flow calculations form the basis of all further analysis of the power system, including economics and stability. This chapter provides models and calculation methods of HVDC grids, particularly when HVDC grids are operating alongside AC grids.

Chapter 14: Deals with the theoretical and practical implementation of optimal power flow (OPF) for DC grids. Both the regular and security constrained OPF are presented as an extension to the deterministic AC optimal power flow case.

Chapter 15: Discusses the control principles of HVDC grids and covers requirements, modes, and strategies for the control of converters, DC networks, and hybrid AC/DC systems. The main focus lies on the power–voltage regulation in DC grids.

Chapter 16: Discusses state-space representation, which is a key tool for steady-state or dynamic analysis of power systems. The chapter describes a methodology to obtain a state-space model of HVDC grids. The procedure is based on combining the equations representing different parts of the transmission grid.

Chapter 17: Deals with DC grid protection, which is a major challenge for the development of an HVDC grid. The behavior of DC short-circuit faults is discussed in this chapter, as well as the special protection requirements of HVDC grids. The chapter summarizes the DC protection methods and algorithms and describes the DC relaying protection equipment.

Chapter 18: Describes the use of real-time simulation and physical experimental tests to validate the operation of HVDC grids and control systems which provide more reliable verification than the use of offline simulation. Physical experimental platforms are the most feasible representation of a real system and can be combined with real-time simulation.

Part V, “Applications,” presents advanced ideas of operation and control HVDC grids. These include optimal control of VSC within HVDC grids to improve HVDC grid dynamics, flexible DC power flow control using advanced control devices, design of an offshore AC hub to remove the need for DC circuit breakers, and AC/DC grid interactions. There are four chapters in this part.

Chapter 19: Discusses the AC/DC grid interactions, focusing on the damping of AC system oscillations, low-frequency oscillation, and subsynchronous resonance (SSR) by using converter control of HVDC grids.

Chapter 20: Presents a design method to achieve optimal droop control of HVDC grid converters in order to improve the dynamic response of grid control.

Chapter 21: Summarizes advanced control devices which can be used in HVDC grids to increase control freedom and flexibility of power regulation. Device configurations, control systems, and control effectiveness are discussed and compared.

Chapter 22: Starts from the fact that, so far, HVDC circuit breakers are not yet commercially available. The chapter discusses a solution without DC circuit breakers for HVDC design, an AC hub, also referred to as the Super-node concept. This idea is particularly suitable for offshore applications. Design and control system of AC hubs is presented. Use of a variable nonstandard frequency idea is described in this chapter.

ACKNOWLEDGMENTS

THE WRITING of this book has only been possible thanks to the support of many. First and foremost, the editors would like to thank all authors of the individual chapters for their contribution. Writing a book in a collaborative manner is not a simple task, but we believe that together we achieved a very nice result. This was not possible without their work. We would also like to thank Toni Pérez-Villegas Morey for his help with the figures and our publisher for dealing with our (minor) delays. The editors would also like to gratefully acknowledge the support from ABB, Alstom Grid, Alstom Renewable Energy, National Grid UK, Nordex, and Siemens (in alphabetical order) for their kind consent of using their pictures and diagrams. Lastly, we would like to thank Pierre Bernard of the Friends of the Supergrid for contributing the Foreword to this book.

We hope that the book proves to be useful for researchers and engineers. The comments and discussions from readers with diverse backgrounds are highly appreciated as the field of HVDC grids is an emerging one and significant research and development is still required to reach the ultimate objective of a secure, sustainable, and cost-effective energy supply with the aid of HVDC grids.

ACRONYMS

AAC

Alternate arm converter

AC

Alternating current

ACE

Area control error

ACER

Agency for the Cooperation of Energy Regulators

AVR

Automatic voltage regulator

BAU

Business as usual

BLDFIG

Brushless DFIG

CACM

Capacity allocation and congestion management

CAES

Compressed air energy storage

CCC

Capacitor commutated converter

CCGT

Combined cycle gas turbine power plant

CCS

Carbon capture and storage

CIGRE

International Council on Large Electric Systems

CPI

Current policy initiative

CPU

Central processing unit

CSC

Current source converter

CSCC

Controlled series capacitor converter

CSP

Concentrated solar power

CTL

Cascaded two level

DACF

Day ahead congestion forecast

DAEs

Differential algebraic equations

DC

Direct current

DCC

Demand connection code

DCCS

Delayed CCS

DCPFC

DC power flow control devices

DFIG

Doubly fed induction generator

DP

Dynamic programming

DSO

Distribution system operator

DSP

Digital signal processor

DST

Diversified supply technologies

EB

Balancing network code

EENS

Expected energy not supplied

EHV

Extra-high voltage

EIB

European investment bank

EMT

Electromagnetic transients

ENTSO-E

European Network for Transmission System Operators for Electricity

ENTSO-G

European Network for Transmission System Operators for Gas

EPR

Ethylene propylene rubber

ER

Energy restoration

ESCR

Effective SCR

EU ETS

European Union Emission Trading Scheme

FACTS

Flexible AC transmission systems

FCA

Forward capacity allocation

FCG

Fully rated converter generators

FCR

Frequency containment reserves

FPGA

Field programmable gate array

FRR

Frequency restoration reserves

GHG

Greenhouse gas

GIL

Gas-insulated lines

GIS

Gas-insulated switchgear

GRT

General ring topology

GSC

Grid side converter

GTO

Gate turn-off thyristor

GUI

Graphical user interface

HEE

High-energy efficiency

HF

High frequency

HIL

Hardware in the loop

HRES

High RES

HTS

High temperature superconducting

HVAC

High-voltage alternating current

HVDC

High-voltage direct current

IEM

Internal electricity market

IGBT