Q. Introduction to power systems?
Thomas A. Edison's work in 1878 on the electric light led to the concept of a centrally located power station with distributed electric power for lighting in a surrounding area. The opening of the historic Pearl Street Station in New York City on September 4, 1882, with dc generators (dynamos) driven by steamengines,marked the beginning of the electric utility industry. Edison's dc systems expanded with the development of three-wire 220-V dc systems. But as transmission distances and loads continued to grow, voltage problems were encountered. With the advent of William Stanley's development of a commercially practical transformer in 1885, alternating current became more attractive than direct current because of the ability to transmit power at high voltage with corresponding lower current and lower line-voltage drops. The first single-phase ac line (21 km at 4 kV) in the United States operated in 1889 between Oregon City and Portland.
Nikola Tesla's work in 1888 on electric machines made evident the advantages of polyphase over single-phase systems. The first three-phase line (12 km at 2.3 kV) in the United States became operational in California during 1893. The three-phase induction motor conceived by Tesla became the workhorse of the industry.
Most electric energy has been generated by steam-powered (accounting for about 85% of U.S. generation) and by water-powered, or hydro, turbine plants (accounting for about 10% of U.S. generation). Gas turbines are also used for short periods to meet peak loads. Steam plants are fueled primarily by coal, gas, oil, and uranium. While coal is the most widely used fuel in the United States, due to its abundance, nuclear units of 1280-MW steam-turbine capacity are in service today. However, rising construction costs, licensing delays, and public concerns have stopped the growth of nuclear capacity in the United States. Other types of electric power generation are also prevalent, accounting for about 1% of U.S. generation. These include wind-turbine generators, solar-cell arrays, tidal power plants, and geothermal power plants, wherein energy in the form of steam or hot water is extracted from the earth's upper crust. Substantial research now under way shows nuclear fusion energy to be the most promising technology for producing safe, pollution-free, and economical electric energy in this century and beyond, since the needed fuel (deuterium) consumed in a nuclear fusion reaction is present in seawater abundantly.