Extra high voltage AC transmission engineering

531 Pages·2013·8.987 MB·English

by  Begamudre, Rakosh Das

E
XTRA
H V
IGH OLTAGE
AC T
RANSMISSION
E
NGINEERING
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E
XTRA
H V
IGH OLTAGE
AC T
RANSMISSION
E
NGINEERING
(FOURTH EDITION)
RAKOSH DAS BEGAMUDRE
Ex-Professor
Department of Electrical Engineering
Indian Institute of Technology, Kanpur, India
New Academic Science Limited
The Control Centre, 11 A Little Mount Sion
Tunbridge Wells, Kent TN1 1YS, UK
www.newacademicscience.co.uk
NEW
ACADEMIC
SCIENCE e-mail: [email protected]
Copyright © 2013 by New Academic Science Limited
The Control Centre, 11 A Little Mount Sion, Tunbridge Wells, Kent TN1 1YS, UK
www.newacademicscience.co.uk • e-mail: [email protected]
ISBN : 978 1 781830 44 4
All rights reserved. No part of this book may be reproduced in any form, by photostat, microfilm,
xerography, or any other means, or incorporated into any information retrieval system, electronic or
mechanical, without the written permission of the copyright owner.
British Library Cataloguing in Publication Data
A Catalogue record for this book is available from the British Library
Every effort has been made to make the book error free. However, the author and publisher have no
warranty of any kind, expressed or implied, with regard to the documentation contained in this book.
Preface to the Third Edition
It is nearly a decade since the publication of the Second Edition of this text-reference book
authored by me and needs a revision. No significant developments have taken place in the basic
theory and principles of E.H.V. transmission engineering, except for increase in transmission-
voltage levels, cables, magnitudes of power-handling capabilities, as well as of course the cost
of equipment and lines.
But two problems that need mentioning are: (1) harmonics injected into the system by
modern extensive use and developments in Static VAR systems which have an effect on control
and communication systems; and (2) effect on human health due to magnetic fields in the
vicinity of the E.H.V. transmission line corridor. The first one of these is a very advanced topic
and cannot be included in a first text on E.H.V. transmission engineering, as well as several
other topics of a research nature fit for graduate-level thesis. The second topic is considered
important enough from epidemiological point of view to necessitate elaboration. Thus a new
addition has been made to Chapter 7 under the title: Magnetic Field Effects of E.H.V. Lines.
Since the date of publication of the first edition, the I.E.E.E. in New York has thought
it fit to introduce an additional transactions called I.E.E.E. Transactions on Power Delivery.
The author has expanded the list of references at the end of the text to include titles of
significant technical papers pertaining to transmission practice.
Vancouver, R.D. BEGAMUDRE
British Columbia, Canada.
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Preface to the First Edition
Extra High Voltage (EHV) A.C. transmission may be considered to have come of age in 1952 when
the first 380–400 kV line was put into service in Sweden. Since then, industrialized countries all
over the world have adopted it. However, it was found high voltage levels have an impact on the
environment because of high surface voltage gradients on conductors which interfere with TV
frequencies. Thus electrostatic fields in the line vicinity, corona effects, losses, audible noise,
carrier interference, radio interference and TVI were recognized as steady-state problems, governing
the line conductor design, line height, and phase-spacing to keep the interfering fields within
limits. The line-charging current is so high that providing synchronous condensers at load end
only was impractical to control voltages at the sending-end and receiving-end buses. Shunt
compensating reactors for voltage control at no load and switched capacitors at load conditions
became necessary. The use of series capacitors to increase power-handling capacity has brought
its own problems such as increased current density, temperature rise of conductors, increased
short-circuit current and subsynchronous resonance. All these are still steady-state problems.
However, the single serious problem encountered with E.H.V. voltage levels is the
overvoltages during switching operations, commonly called switching-surge overvoltages. Very
soon it was found that a long airgap was weakest for positive polarity switching-surges. The
coordination of insulation must now be based on switching impulse levels (SIL) and not on lightning
impulse levels only.
Investigation high-voltage effects from E.H.V. and U.H.V. lines have brought line designs to
a more scientific basis, although all variables in the problem are statistical in nature and require
long-term observations. Along with field data, analysis of various problems and calculations using
the Digital Computer have advanced the state of the art of E.H.V. line designs to a high level of
scientific attainment. Most basic mechanisms are now on a firm footing, although there is an
endless list of problems that require satisfactory solution.
During my long teaching career for undergraduate and postgraduate courses on High Voltage
A.C. Transmission I have not found a suitable text book. The existing text books are either for
first courses in High Voltage Engineering concentrating on breakdown phenomena of solid, liquid,
gaseous and vacuum insulation, together with high voltage laboratory and measurement
techniques, or reference books of very highly specialized levels. To bridge the gap, this text-
reference book for a course in EHV A.C. Transmission is presented. The material has been tried
out on advanced courses at the I.I.T. Kanpur, in special short-term courses offered to teachers
and practising engineers through the Quality Improvement Programme. Some of the material is
based on the author's own work at the National Research Council of Canada, and similar
organizations in India, over the past 25 years. But no single person or organization can hope to
viii Preface
deal with all problems so that over the years, the author's notes have grown through reference
work of technical and scientific journals which have crystallized into the contents of the book. It
is hoped that it will be useful also for engineers as well as scientists engaged in research,
development, design, and decision-making about E.H.V. a.c. transmission lines.
Acknowledgements
The preparation of such a work has depended on the influence, cooperation and courtesy of many
organizations and individuals. To start with, I acknowledge the deep influence which three of my
venerable teachers had on my career—Principal Manoranjan Sengupta at the Banaras Hindu
University, Professor Dr. Shigenori Hayashi at the Kyoto University, Japan, and finally to Dean
Loyal Vivian Bewley who exercised the greatest impact on me in the High Voltage field at the
Lehigh University, Bethlehem, Pennsylvania, USA. Thanks finally are due to my colleagues,
postgraduate students, who have helped me at many stages in preparing this book.
RAKOSH DAS BEGAMUDRE
Contents
Preface to the Third Edition.................................................................................v
Preface to the First Edition............................................................................... vii
Chapter 1 Introduction to EHV AC Transmission.....................................................3–8
1.1 Role of EHV AC Transmission ..............................................................................3
1.2 Brief Description of Energy Sources and their Development................................3
1.3 Description of Subject Matter of this Book ..........................................................4
Chapter 2 Transmission Line Trends and Preliminaries......................................9–21
2.1 Standard Transmission Voltages ..........................................................................9
2.2 Average Values of Line Parameters....................................................................11
2.3 Power-Handling Capacity and Line Loss............................................................11
2.4 Examples of Giant Power Pools and Number of Lines .......................................14
2.5 Costs of Transmission Lines and Equipment .....................................................15
2.6 Mechanical Considerations in Line Performance ...............................................17
Chapter 3 Calculation of Line and Ground Parameters......................................22–60
3.1 Resistance of Conductors.....................................................................................22
3.2 Temperature Rise of Conductors and Current-Carrying Capacity.....................26
3.3 Properties of Bundled Conductors.......................................................................28
3.4 Inductance of EHV Line Configurations .............................................................30
3.5 Line Capacitance Calculation..............................................................................38
3.6 Sequence Inductances and Capacitances ............................................................41
3.7 Line Parameters for Modes of Propagation.........................................................44
3.8 Resistance and Inductance of Ground Return ....................................................50
Chapter 4 Voltage Gradients of Conductors.........................................................61–112
4.1 Electrostatics.......................................................................................................61
4.2 Field of Sphere Gap .............................................................................................63