High Voltage Direct Current Transmission

296 Pages·2008·13.473 MB·English

by  Jos Arrillaga

IET PowEr and EnErgy sErIES, VOLUME 29
High Voltage Direct
Current Transmission
2nd Edition
Jos Arrillaga
The Institution of Engineering and Technology
Published by The Institution of Engineering and Technology, London, United Kingdom
First edition © 1998 The Institution of Electrical Engineers
Reprint with new cover © 2008 The Institution of Engineering and Technology
First published 1998
Reprinted with new cover 2008
This publication is copyright under the Berne Convention and the Universal Copyright
Convention. All rights reserved. Apart from any fair dealing for the purposes of research
or private study, or criticism or review, as permitted under the Copyright, Designs and
Patents Act, 1988, this publication may be reproduced, stored or transmitted, in any
form or by any means, only with the prior permission in writing of the publishers, or in
the case of reprographic reproduction in accordance with the terms of licences issued
by the Copyright Licensing Agency. Inquiries concerning reproduction outside those
terms should be sent to the publishers at the undermentioned address:
The Institution of Engineering and Technology
Michael Faraday House
Six Hills Way, Stevenage
Herts, SG1 2AY, United Kingdom
www.theiet.org
While the author and the publishers believe that the information and guidance given
in this work are correct, all parties must rely upon their own skill and judgement when
making use of them. Neither the author nor the publishers assume any liability to
anyone for any loss or damage caused by any error or omission in the work, whether
such error or omission is the result of negligence or any other cause. Any and all such
liability is disclaimed.
The moral rights of the author to be identified as author of this work have been
asserted by him in accordance with the Copyright, Designs and Patents Act 1988.
British Library Cataloguing in Publication Data
A CIP catalogue record for this book is available from the British Library
ISBN (10 digit) 0 85296 941 4
ISBN (13 digit) 978-0-85296-941-0
Printed in the UK by Short Run Press Ltd, Exeter
Reprinted in the UK by Lightning Source UK Ltd, Milton Keynes
Preface
The high voltage mercury-arc valve and its application to the development
of an HVDC transmission technology have been described in earlier books
by Adamson and Hingorani, Kimbark and Uhlmann. In common with
these texts the first edition of this book, published in 1983, described the
basic principles of static power conversion and their application to power
transmission by high-voltage direct current.
By then, however, in parallel with the development of microelectronic
technology there had been an equally impressive, although less publicised,
macroelectronic development in the power field sharing the same basic
ingredients, i.e. switching and silicon. The main exponent of macroelectro-
nic technology must surely be the solid-state HVDC valve. By the time the
first edition of this book was being prepared, thyristors had already
displaced mercury-arc valves in new HVDC schemes, and the book
reflected the change. Although the basic principles of operation remain
the same, the past 15 years have seen a worldwide acceptance of HVDC
and particularly the installation of a large number of back-to-back inter-
connections. There have also been substantial improvements in the ratings
and reliability of thyristor valves and the appearance of more controllable
solid-state devices; the latter have encouraged a new technology called
FACTS (flexible AC transmission systems) which is proving to be very
competitive with HVDC for some specific applications. However, thyristor
technology has not remained at a standstill and a variety of new concepts
and techniques have been appearing with the aim of reducing the cost of
HVDC and extending its area of application.
This expanded edition of the book includes the main technical advances
of the past 15 years and describes the new concepts which, no doubt, will
help to make HVDC even more competitive in the new millennium.
Again, I would like to acknowledge the valuable help received early
on from all the experts mentioned in the first edition and extend my
gratitude to my present colleagues C.P. Arnold, P.S. Bodger, S. Chen,
xii Preface
W. Enright, B.C. Smith, N.R. Watson and A.R. Wood for their support
and dedication to the HVDC cause. I acknowledge the continued encour-
agement and financial assistance received from TransPower NZ Ltd for
our research into HVDC transmission.
It would be difficult to properly acknowledge all the sources of informa-
tion used in the preparation of this book; I must, however, single out the
vast amount of work carried out by CIGRE study committee 14 on HVDC
transmission from which I have derived inspiration, the practical informa-
tion and photographs obtained from industry, especially GEC-Alsthom
and ABB, and the close collaboration that I have had over the years with
the Manitoba HVDC Research Centre.
Contents
Preface xi
1 Introduction 1
1.1 Historical background 1
1.2 The mercury-arc valve 3
1.3 The silicon controlled rectifier (thyristor) 4
1.4 Future switching trends 7
1.5 The HVDC claims 8
1.6 The advent of a FACTS technology 8
1.7 References 9
2 Static power conversion 10
2.1 Introduction 10
2.2 Basic conversion principle 10
2.3 Selection of converter configuration 13
2.4 The ideal commutation process 13
2.4.1 Effect of gate control 14
2.4.2 Valve current and voltage waveforms 17
2.5 The real commutation process 18
2.5.1 Commutating voltage 18
2.5.2 Commutation reactance 19
2.5.3 Analysis of the commutation circuit 23
2.6 Rectifier operation 24
2.6.1 Mean direct voltage 26
2.6.2 AC current 27
2.7 Inverter operation 27
2.8 Power factor and reactive power 28
2.9 Maximum available power 32
2.10 Characteristic converter harmonics 33
2.11 Noncharacteristic harmonics 39
2.11.1 Harmonic crossmodulation 42
vi Contents
2.12 Harmonic transfer generalisation 50
2.13 Quantified effects of system asymmetries 52
2.14 References 55
Harmonic elimination 56
3.1 Introduction 56
3.2 Pulse number increase 56
3.3 Design of AC filters 57
3.3.1 Design criteria 57
3.3.2 Design factors 58
3.3.3 Network impedance 62
3.3.4 Circuit modelling 70
3.3.5 Tuned filters 70
3.3.6 Self-tuned filters 72
3.3.7 High-pass filters 73
3.3.8 Example of recent filter arrangement 74
3.3.9 Type C damped filters 74
3.3.10• Simplified filtering for 12-pulse converters 76
3.4 DC-side filters 77
3.5 Active; filters 80
3.5.1 AC-side active cancellation 80
3.5.2 DC-side active cancellation 81
3.6 References 82
HVDC system development 84
4.1 Basic DC system configurations 84
4.2 Mercury-arc schemes 86
4.3 Evolution of the modern solid-state HVDC scheme 88
4.3.1 Frequency conversion 93
4.3.2 Asynchronous back-to-back interconnections 93
4.4 Operation reliability 97
4.5 References 97
Control of HVDC converters and systems 100
A - CONVERTER CONTROL 100
5.1 Basic philosophy 100
5.2 Individual phase control 101
5.3 Equidistant firing control 103
5.3.1 Constant-current loop 104
5.3.2 Inverter extinction-angle control 105
5.3.3 Transition from extinction-angle to current control 106
5.3.4 Other equidistant firing-control schemes 106
5.3.5 Application to 12-pulse converter groups 108
5.3.6 Comparative merits 108
Contents vii
B - DC SYSTEM CONTROL 111
5.4 Basic philosophy 111
5.5 Characteristics and direction of DC-power flow 112
5.5.1 Tap-changer control 115
5.5.2 Reversal of power flow 116
5.5.3 Modifications to the basic characteristics 117
5.5.4 Operational nonminimum margin angle 118
5.5.5 Power-flow control 119
5.5.6 Frequency control 120
5.5.7 Power/frequency control 121
5.6 Different control levels 121
5.6.1 Overall control co-ordination 123
5.6.2 Hierarchical power control at the New Zealand link 124
5.7 Telecommunication requirements 126
5.8 References 128
6 Interaction between AC and DC systems 129
6.1 Introduction 129
6.2 System strength definition 130
6.2.1 AC-system Thevenin equivalent 130
6.3 Voltage interaction 132
6.3.1 Dynamic voltage regulation 133
6.4 Dynamic stabilisation of AC systems 136
6.4.1 Large-signal modulation 138
6.4.2 Controlled damping of DC-interconnected systems 138
6.4.3 Damping of su bsynchronous resonances 140
6.4.4 Active and reactive-power co-ordination 141
6.4.5 Transient stabilisation of AC systems 142
6.5 AC-DC frequency interactions 143
6.6 Harmonic instabilities 144
6.6.1 Instability caused by individual firing control 145
6.6.2 Composite resonances 148
6.6.3 Transformer-core-related harmonic instability 150
6.7 AC-DC interaction following disturbances 155
6.7.1 AC-side fault recovery 155
6.7.2 DC-side fault recovery 156
6.8 References 157
7 Main design considerations 159
7.1 Introduction 159
7.2 Mercury-arc circuit components 160
7.2.1 Valve group 160
7.2.2 Converter station 160
7.2.3 Mercury-arc converter layout 162
7.3 Thyristor valves 162
viii Contents
7.3.1 Electrical considerations 162
7.3.2 Mechanical considerations 165
7.3.3 Valve-cooling system 167
7.3.4 Valve-control circuitry 168
7.3.5 Valve tests 171
7.3.6 Valve-hall arrangement 174
1A Station layout 174
7.5 Relative costs of converter components 176
7.6 Converter transformers 178
7.7 Smoothing reactors 181
7.8 Overhead lines 182
7.9 Cable transmission 184
7.10 Earth electrodes 190
7.11 Design of back-to-back thyristor converter systems 192
7.12 HVDC system upgrade 194
7.12.1 The converter stations 195
7.12.2 DC transmission line 197
7.12.3 Submarine power cables 198
7.13 References 198
Fault development and protection 200
8.1 Introduction 200
8.2 Converter disturbances 200
8.2.1 Misfire and firethrough 201
8.2.2 Commutation failure 201
8.2.3 Backfire 207
8.2.4 Internal short circuit 207
8.2.5 Bypass action 208
8.2.6 Bypass action in thyristor bridges 209
8.3 Simulation of practical disturbances 210
8.4 AC-system faults 211
8.4.1 Three-phase faults 214
8.4.2 Unsymmetrical faults 214
8.5 DC-line fault development 216
8.5.1 Fault detection 218
8.5.2 Fault clearing and recovery 219
8.5.3 Overall dynamic response 219
8.6 Overcurrent protection 221
8.6.1 Valve-group protection 224
8.6.2 DC-line protection 225
8.6.3 Filter protection 226
8.7 References 226
Transient overvoltages and insulation co-ordination 228
9.1 Introduction 228
Contents ix
9.2 Overvoltages excited by disturbances on the* DC side 229
9.3 Harmonic overvoltages excited by AC disturbances 231
9.4 Overvoltages owing to converter disturbances 232
9.5 Fast transients generated on the DC system 233
9.5.1 Lightning surges 233
9.5.2 Switching-type surges 235
9.6 Surges generated on the AC system 235
9.7 Fast transient phenomena associated with the converter
plant 238
9.7.1 Mercury-arc converters 238
9.7.2 Thyristor converters 240
9.8 Insulation co-ordination 243
9.8.1 System design 243
9.8.2 Surge arresters 244
9.8.3 Application of surge arresters 245
9.9 Considerations on cable overvoltage protection 250
9.10 References 251
10 DC versus AC transmission 253
10.1 General considerations 253
10.2 Power-carrying capability of AC and DC lines 255
10.3 A comparison of AC and DC transmission characteristics 258
10.4 Other considerations 259
10.5 Infeeds at lower voltage levels 263
10.6 Examples of the application of the break-even distance 264
10.7 Environmental effects 266
10.7.1 Electric field 266
10.7.2 Radiated interference 267
10.7.3 Acoustic noise 269
10.7.4 Visual impact and space requirements 270
10.8 Existing AC transmission facilities converted for use
with DC 270
10.9 Very long-distance transmission 273
10.10 References 276
11 New concepts in HVDC converters and systems 278
11.1 Introduction 278
11.2 Advanced devices 278
11.2.1 Thyristor development 278
11.2.2 Gate turn-off semiconductors (GTO) 279
11.3 New concepts for thyristor converters 279
11.3.1 Capacitor-commutated converter 280
11.3.2 Continuously-tuned AC filters 282
11.3.3 Outdoor valves 283
11.4 Compact converter stations 285
x Contents
11.5 GTO-based voltage-source converters 286
11.5.1 A GTO back-to-back HVDC link 287
11.5.2 HVDC light 289
11.6 DC cable developments 289
11.7 Direct connection of generators to HVDC converters 290
11.8 Small HVDC tappings 292
11.9 References 294
Index 296