Extra high voltage ac transmission engineering

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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 theses and dissertations. 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.


Introduction to EHV AC Transmission



ROLE OF EHV AC TRANSMISSION
Industrial-minded countries of the world require a vast amount of energy of which electrical
energy forms a major fraction. There are other types of energy such as oil for transportation
and industry, natural gas for domestic and industrial consumption, which form a considerable
proportion of the total energy consumption. Thus, electrical energy does not represent the
only form in which energy is consumed but an important part nevertheless. It is only 150 years
since the invention of the dynamo by Faraday and 120 years since the installation of the first
central station by Edison using dc. But the world has already consumed major portion of its
natural resources in this short period and is looking for sources of energy other than hydro and
thermal to cater for the rapid rate of consumption which is outpacing the discovery of new
resources. This will not slow down with time and therefore there exists a need to reduce the
rate of annual increase in energy consumption by any intelligent society if resources have to be
preserved for posterity. After the end of the Second World War, countries all over the world
have become independent and are showing a tremendous rate of industrial development, mostly
on the lines of North-American and European countries, the U.S.S.R. and Japan. Therefore,
the need for energy is very urgent in these developing countries, and national policies and
their relation to other countries are sometimes based on energy requirements, chiefly nuclear.
Hydro-electric and coal or oil-fired stations are located very far from load centres for various
reasons which requires the transmission of the generated electric power over very long distances.
This requires very high voltages for transmission. The very rapid strides taken by development
of dc transmission since 1950 is playing a major role in extra-long-distance transmission,
complementing or supplementing e.h.v. ac transmission. They have their roles to play and a
country must make intelligent assessment of both in order to decide which is best suited for
the country's economy. This book concerns itself with problems of e.h.v. ac transmission only.
1.2 BRIEF DESCRIPTION OF ENERGY SOURCES AND THEIR
DEVELOPMENT
Any engineer interested in electrical power transmission must concern himself or herself with
energy problems. Electrical energy sources for industrial and domestic use can be divided into
two broad categories: (1) Transportable; and (2) Locally Usable.
1Introduction to EHV AC Transmission

2 Extra High Voltage AC Transmission Engineering
Transportable type is obviously hydro-electric and conventional thermal power. But locally
generated and usable power is by far more numerous and exotic. Several countries, including
India, have adopted national policies to investigate and develop them, earmarking vast sums of
money in their multi-year plans to accelerate the rate of development. These are also called
'Alternative Sources of Power'. Twelve such sources of electric power are listed here, but there
are others also which the reader will do well to research.
Locally Usable Power
(1) Conventional thermal power in urban load centres;
(2) Micro-hydel power stations;
(3) Nuclear Thermal: Fission and Fusion;
(4) Wind Energy;
(5) Ocean Energy: (a) Tidal Power, (b) Wave Power, and © Ocean thermal gradient
power;
(6) Solar thermal;
(7) Solar cells, or photo-voltaic power;
(8) Geo-thermal;
(9) Magneto hydro-dynamic or fluid dynamic;
(10) Coal gasification and liquefaction;
(11) Hydrogen power; and last but not least,
(12) Biomass Energy: (a) Forests; (b) Vegetation; and © Animal refuse.