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The Nelson River DC Transmission System, also known as the Manitoba Bipole, is an electric power transmission system of two high voltage, direct current lines in Manitoba, Canada, operated by Manitoba Hydro as part of the Nelson River Hydroelectric Project. It is now recorded on the list of IEEE Milestones in electrical engineering. Several records have been broken by successive phases of the project, including the largest (and last) mercury-arc valves, the highest DC transmission voltage and the first use of water-cooled thyristor valves in HVDC. The system transfers electric power generated by several hydroelectric power stations along the Nelson River in Northern Manitoba across the wilderness to the populated areas in the south. It includes two rectifier stations, Radisson Converter Station near Gillam at and Henday Converter Station near Sundance at , one inverter station, Dorsey Converter Station at Rosser located north west of Winnipeg at ), and two sets of high-voltage direct current transmission lines. Each HVDC transmission line has two parallel overhead conductors to carry the positive and negative feeds. There are no intermediate switching stations or taps. Both bipolar systems have extensive ground return electrodes to allow use in monopolar mode. ==History== Construction in 1966 of the 1,272 MW Kettle Rapids generating station required a long transmission line to connect it to load centers in the southern part of Manitoba. The Government of Canada agreed to finance installation of an HVDC line to be repaid by Manitoba Hydro when the load growth permitted the utility to assume the debt due to the line. Delivery of direct current electric power began on June 17, 1972. One unit of the Kettle generating station was completed before the direct current converters were completed.〔Leonard A. Bateman, ''An Engineering Career in the Hydroelectric Industry'', Engineering Institute of Canada Working Paper 22/2004, July 2004〕 For the winter of 1970 the bipole lines were energized with alternating current, contributing a useful amount of energy to the Manitoba system; a shunt reactor was installed to prevent excess voltage rise due to the Ferranti effect. At that time, Bipole I used the world's highest operating voltage to deliver the largest amount of power from a remote site to a city, and employed the largest mercury arc valves ever developed for such an application. The line required construction of over 3,900 guyed towers and 96 self-supporting towers across varied terrain. Permafrost in some areas led to foundation settling of up to 3 feet (1 m). The loan by the Government of Canada was discharged when Manitoba Hydro bought the line and outstanding debt in 1992.〔L. A. Bateman, "A History of Electric Power Development in Manitoba", in IEEE Canadian Review, Winter 2005〕 In 1997 a tornado damaged 19 towers of the DC lines. During repairs, some major customers were advised to curtail load, but imports over the 500 kV lines from adjacent utilities in the United States prevented serious interruption of power. A third such line, called Bipole 3 has been proposed, with current plans calling for it to run along the west side of Manitoba. On October 26, 2009, the Canadian Taxpayers Federation, along with engineering and environmental experts, released an analysis which they claimed refuted each of the government's claims for why the line must be built down the west side of the province.〔 ()〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Nelson River DC Transmission System」の詳細全文を読む スポンサード リンク
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