HISTORY OF ELECTRIC POWER SYSTEMS
Over the past century, the electric power industry continues to shape
and contribute to the welfare, progress, and technological advances of the
human race. The growth of electric energy consumption in the world has been
nothing but phenomenal. In the United States, for example, electric energy sales
have grown to well over 400 times in the period between the turn of the century
and the early 1970s. This growth rate was 50 times as much as the growth rate
in all other energy forms used during the same period. It is estimated that the
installed kW capacity per capita in the U.S. is close to 3 kW.
and contribute to the welfare, progress, and technological advances of the
human race. The growth of electric energy consumption in the world has been
nothing but phenomenal. In the United States, for example, electric energy sales
have grown to well over 400 times in the period between the turn of the century
and the early 1970s. This growth rate was 50 times as much as the growth rate
in all other energy forms used during the same period. It is estimated that the
installed kW capacity per capita in the U.S. is close to 3 kW.
Edison Electric Illuminating Company of New York inaugurated the
Pearl Street Station in 1881. The station had a capacity of four 250-hp boilers
supplying steam to six engine-dynamo sets. Edison’s system used a 110-V dc
underground distribution network with copper conductors insulated with a jute
wrapping. In 1882, the first water wheel-driven generator was installed in
Appleton, Wisconsin. The low voltage of the circuits limited the service area of
a central station, and consequently, central stations proliferated throughout
metropolitan areas.
The invention of the transformer, then known as the “inductorium,”
made ac systems possible. The first practical ac distribution system in the U.S.
was installed by W. Stanley at Great Barrington, Massachusetts, in 1866 for
Westinghouse, which acquired the American rights to the transformer from its
British inventors Gaulard and Gibbs. Early ac distribution utilized 1000-V
overhead lines. The Nikola Tesla invention of the induction motor in 1888
helped replace dc motors and hastened the advance in use of ac systems.
made ac systems possible. The first practical ac distribution system in the U.S.
was installed by W. Stanley at Great Barrington, Massachusetts, in 1866 for
Westinghouse, which acquired the American rights to the transformer from its
British inventors Gaulard and Gibbs. Early ac distribution utilized 1000-V
overhead lines. The Nikola Tesla invention of the induction motor in 1888
helped replace dc motors and hastened the advance in use of ac systems.
The first American single-phase ac system was installed in Oregon in
1889. Southern California Edison Company established the first three phase 2.3
kV system in 1893.
By 1895, Philadelphia had about twenty electric companies with
distribution systems operating at 100-V and 500-V two-wire dc and 220-V
three-wire dc, single-phase, two-phase, and three-phase ac, with frequencies of
60, 66, 125, and 133 cycles per second, and feeders at 1000-1200 V and 2000-
2400 V.
The subsequent consolidation of electric companies enabled the
realization of economies of scale in generating facilities, the introduction of
equipment standardization, and the utilization of the load diversity between
areas. Generating unit sizes of up to 1300 MW are in service, an era that was
started by the 1973 Cumberland Station of the Tennessee Valley Authority.
Underground distribution at voltages up to 5 kV was made possible by
the development of rubber-base insulated cables and paper-insulated, leadcovered
cables in the early 1900s. Since then, higher distribution voltages have
been necessitated by load growth that would otherwise overload low-voltage
circuits and by the requirement to transmit large blocks of power over great
distances. Common distribution voltages presently are in 5-, 15-, 25-, 35-, and
69-kV voltage classes.
realization of economies of scale in generating facilities, the introduction of
equipment standardization, and the utilization of the load diversity between
areas. Generating unit sizes of up to 1300 MW are in service, an era that was
started by the 1973 Cumberland Station of the Tennessee Valley Authority.
Underground distribution at voltages up to 5 kV was made possible by
the development of rubber-base insulated cables and paper-insulated, leadcovered
cables in the early 1900s. Since then, higher distribution voltages have
been necessitated by load growth that would otherwise overload low-voltage
circuits and by the requirement to transmit large blocks of power over great
distances. Common distribution voltages presently are in 5-, 15-, 25-, 35-, and
69-kV voltage classes.
The growth in size of power plants and in the higher voltage equipment
was accompanied by interconnections of the generating facilities. These
interconnections decreased the probability of service interruptions, made the
utilization of the most economical units possible, and decreased the total reserve
capacity required to meet equipment-forced outages. This was accompanied by
use of sophisticated analysis tools such as the network analyzer. Central control
of the interconnected systems was introduced for reasons of economy and
safety. The advent of the load dispatcher heralded the dawn of power systems
engineering, an exciting area that strives to provide the best system to meet the
load requirements reliably, safely, and economically, utilizing state-of-the-art
computer facilities.
Extra higher voltage (EHV) has become dominant in electric power
transmission over great distances. By 1896, an 11-kv three-phase line was
transmitting 10 MW from Niagara Falls to Buffalo over a distance of 20 miles.
Today, transmission voltages of 230 kV, 287 kV, 345 kV, 500 kV, 735 kV, and
765 kV are commonplace, with the first 1100-kV line already energized in the
early 1990s. The trend is motivated by economy of scale due to the higher
transmission capacities possible, more efficient use of right-of-way, lower
transmission losses, and reduced environmental impact.
In 1954, the Swedish State Power Board energized the 60-mile, 100-kV
dc submarine cable utilizing U. Lamm’s Mercury Arc valves at the sending and
receiving ends of the world’s first high-voltage direct current (HVDC) link
connecting the Baltic island of Gotland and the Swedish mainland. Currently,
numerous installations with voltages up to 800-kV dc are in operation around
the world.
In North America, the majority of electricity generation is produced by
investor-owned utilities with a certain portion done by federally and provincially
(in Canada) owned entities. In the United States, the Federal Energy Regulatory
Commission (FERC) regulates the wholesale pricing of electricity and terms and
conditions of service.
The North American transmission system is interconnected into a large
power grid known as the North American Power Systems Interconnection. The
grid is divided into several pools. The pools consist of several neighboring
utilities which operate jointly to schedule generation in a cost-effective manner.
A privately regulated organization called the North American Electric
Reliability Council (NERC) is responsible for maintaining system standards and
reliability. NERC works cooperatively with every provider and distributor of
power to ensure reliability. NERC coordinates its efforts with FERC as well as
other organizations such as the Edison Electric Institute (EEI). NERC currently
has four distinct electrically separated areas. These areas are the Electric
Reliability Council of Texas (ERCOT), the Western States Coordination
Council (WSCC), the Eastern Interconnect, which includes all the states and
provinces of Canada east of the Rocky Mountains (excluding Texas), and
Hydro-Quebec. These electrically separate areas exchange with each other but
are not synchronized electrically.
power grid known as the North American Power Systems Interconnection. The
grid is divided into several pools. The pools consist of several neighboring
utilities which operate jointly to schedule generation in a cost-effective manner.
A privately regulated organization called the North American Electric
Reliability Council (NERC) is responsible for maintaining system standards and
reliability. NERC works cooperatively with every provider and distributor of
power to ensure reliability. NERC coordinates its efforts with FERC as well as
other organizations such as the Edison Electric Institute (EEI). NERC currently
has four distinct electrically separated areas. These areas are the Electric
Reliability Council of Texas (ERCOT), the Western States Coordination
Council (WSCC), the Eastern Interconnect, which includes all the states and
provinces of Canada east of the Rocky Mountains (excluding Texas), and
Hydro-Quebec. These electrically separate areas exchange with each other but
are not synchronized electrically.
The electric power industry in the United States is undergoing
fundamental changes since the deregulation of the telecommunication, gas, and
other industries. The generation business is rapidly becoming market-driven.
The power industry was, until the last decade, characterized by larger, vertically
integrated entities. The advent of open transmission access has resulted in
wholesale and retail markets. Utilities may be divided into power generation,
transmission, and retail segments. Generating companies (GENCO) sell directly
to an independent system operator (ISO). The ISO is responsible for the
operation of the grid and matching demand and generation dealing with
transmission companies as well (TRANSCO). This scenario is not the only
possibility, as the power industry continues to evolve to create a more
competitive environment for electricity markets to promote greater efficiency.
The industry now faces new challenges and problems associated with the
interaction of power system entities in their efforts to make crucial technical
decisions while striving to achieve the highest level of human welfare.
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