A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages between 100 kV and 800 kV.
The HVDC Cross-Channel is the 73-kilometre-long (45 mi) high-voltage direct current (HVDC) interconnector that has operated since 1986 under the English Channel between the continental European grid at Bonningues-lès-Calais and the British electricity grid at Sellindge. The cable is also known as IFA, and should not be confused with the new IFA-2, another interconnect with France that is three times as long but only half as powerful.
The HVDC Inter-Island link is a 610 km (380 mi) long, 1200 MW high-voltage direct current (HVDC) transmission system connecting the electricity networks of the North Island and South Island of New Zealand together. It is commonly referred to as the Cook Strait cable in the media and in press releases, although the link is much longer than its Cook Strait section. The link is owned and operated by state-owned transmission company Transpower New Zealand.
The Pacific DC Intertie is an electric power transmission line that transmits electricity from the Pacific Northwest to the Los Angeles area using high voltage direct current (HVDC). The line capacity is 3.1 gigawatts, which is enough to serve two to three million Los Angeles households and represents almost half of the Los Angeles Department of Water and Power (LADWP) electrical system's peak capacity.
The Nelson River DC Transmission System, also known as the Manitoba Bipole, is an electric power transmission system of three 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 mercury-arc valves, the highest DC transmission voltage and the first use of water-cooled thyristor valves in HVDC.
HVDC Kingsnorth was a high-voltage direct-current (HVDC) transmission system connecting Kingsnorth in Kent to two sites in London. It was at one time the only application of the technology of high voltage direct current transmission for the supply of transformer stations in a city, and the first HVDC link to be embedded within an AC system, rather than interconnecting two asynchronous systems. It was also the first HVDC scheme to be equipped with self-tuning harmonic filters and to be controlled with a "Phase Locked Oscillator", a principle which subsequently became standard on all HVDC systems.
The Inga–Shaba EHVDC Intertie is a 1,700 kilometres (1,100 mi)-long high-voltage direct current overhead electric power transmission line in the Democratic Republic of Congo, linking the Inga hydroelectric complex at the mouth of the Congo River to mineral fields in Shaba (Katanga). It was primarily constructed by Morrison-Knudsen International, an American engineering company, with the converter equipment supplied by ASEA. Construction was completed in 1982 and it cost US$900 million. The scheme was, for many years, the longest HVDC line in the world.
An HVDC converter station is a specialised type of substation which forms the terminal equipment for a high-voltage direct current (HVDC) transmission line. It converts direct current to alternating current or the reverse. In addition to the converter, the station usually contains:
The HVDC Itaipu is a High-voltage direct current overhead line transmission system in Brazil from the Itaipu hydroelectric power plant to the region of São Paulo. The project consists of two ±600 kV bipoles, each with a rated power of 3150 MW, which transmit power generated at 50 Hz from the Paraguay side of the Itaipu Dam to the Ibiúna converter station near São Roque, São Paulo. The system was put in service in several steps between 1984 and 1987, and remains among the most important HVDC installations in the world.
Path 27, also called the Intermountain or the Southern Transmission System (STS), is a high-voltage direct current (HVDC) electrical transmission line running from the coal-fired Intermountain Power Plant near Delta, Utah, to the Adelanto Converter Station at Adelanto, California, in the Southwestern United States. It was installed by Asea, a company based in Sweden, and commercialized in July 1986. The system is designed to carry power generated at the power plant in Utah to areas throughout Southern California. It is owned and operated by the Intermountain Power Agency, a cooperative consisting of six Los Angeles-area cities, the largest member being the Los Angeles Department of Water and Power (LADWP), and 29 smaller Utah municipalities.
Square Butte is the designation of a high-voltage direct current transmission line in the United States between the Milton R. Young Power Plant near Center, North Dakota at 47°4′18″N101°11′45″W and the Arrowhead converter station near Adolph at 46°46′25″N92°17′39″W. It was built by Minnkota Power Cooperative and Minnesota Power and went in service in 1977. In 2009, an agreement was executed between the two companies whereby Minnkota gets the rights to all the power currently transmitted over the line while Minnesota Power takes full ownership of the line to transmit power from new sources in the Center area.
Shin-Shinano Frequency Converter is the designation of a back-to-back high-voltage direct current (HVDC) facility in Japan which forms one of four frequency converter stations that link Japan's western and eastern power grids. The other three stations are at Higashi-Shimizu, Minami-Fukumitsu, and Sakuma Dam.
The GK Dürnrohr was a high-voltage direct current back-to-back scheme west of Dürnrohr substation, which was used for the energy exchange between Austria and Czechoslovakia between 1983 and 1996. The installation is no longer in use.
The Sakuma Dam is a dam on the Tenryū River, located on the border of Toyone, Kitashitara District, Aichi Prefecture on the island of Honshū, Japan. It is one of the tallest dams in Japan and supports a 350 MW hydroelectric power station. Nearby a frequency converter station is installed, allowing interchange of power between Japan's 50 Hz and 60 Hz AC networks.
Zhoushan HVDC was the first HVDC scheme built in China and first put into service in July 2014.
The HVDC Hokkaidō–Honshū or Hokkaidō–Honshū HVDC Link, Kitahon HVDC Link for short, is a 193-kilometre-long (120 mi) high voltage direct current transmission line for the interconnection of the power grids of Hokkaidō and Honshū, Japan. The project went into service in 1979 by the Electric Power Development Company (J-POWER). A 149-kilometre-long (93 mi) overhead line and a 44-kilometre-long (27 mi) submarine cable connect the terminals. The HVDC Hokkaidō–Honshū is a monopolar HVDC line with an operating voltage of 250 kV and rated power of 300 megawatts. This HVDC system uses thyristor converters.
The Moscow–Kashira HVDC transmission system was an early high-voltage direct current (HVDC) connection between the town of Kashira and the city of Moscow in Russia, where the terminal was at 55°39′32″N37°38′16″E. The system was built using mercury-arc valves and other equipment removed from the Elbe Project in Berlin at the end of World War II. Although primarily experimental in nature, the system was the first true static, electronic, high-voltage DC scheme to enter service. Earlier DC transmission schemes had either used electromechanical converters based on the Thury system, such as the Lyon–Moutiers DC transmission scheme or had been at only medium voltage, such as the 12 kV frequency converter scheme at Mechanicville, New York in the United States.
An HVDC converter converts electric power from high voltage alternating current (AC) to high-voltage direct current (HVDC), or vice versa. HVDC is used as an alternative to AC for transmitting electrical energy over long distances or between AC power systems of different frequencies. HVDC converters capable of converting up to two gigawatts (GW) and with voltage ratings of up to 900 kilovolts (kV) have been built, and even higher ratings are technically feasible. A complete converter station may contain several such converters in series and/or parallel to achieve total system DC voltage ratings of up to 1,100 kV.
The Rio Madeira HVDC system is a high-voltage direct current transmission system in Brazil, built to export power from new hydro power plants on the Madeira River in the Amazon Basin to the major load centres of southeastern Brazil. The system consists of two converter stations at Porto Velho in the state of Rondônia and Araraquara in São Paulo state, interconnected by two bipolar ±600 kV DC transmission lines with a capacity of 3,150 megawatts (4,220,000 hp) each. In addition to the converters for the two bipoles, the Porto Velho converter station also includes two 400 MW back-to-back converters to supply power to the local 230 kV AC system. Hence the total export capacity of the Porto Velho station is 7100 MW: 6300 MW from the two bipoles and 800 MW from the two back-to-back converters. When Bipole 1 commenced commercial operation in 2014, Rio Madeira became the world’s longest HVDC line, surpassing the Xiangjiaba–Shanghai system in China. According to the energy research organisation Empresa de Pesquisa Energética (EPE), the length of the line is 2,375 kilometres (1,476 mi).
The Xiangjiaba–Shanghai HVDC system is a ±800 kV, 6400 MW high-voltage direct current transmission system in China. The system was built to export hydro power from Xiangjiaba Dam in Sichuan province, to the major city of Shanghai. Built and owned by State Grid Corporation of China (SGCC), the system became the world’s largest-capacity HVDC system when it was completed in July 2010, although it has already been overtaken by the 7200 MW Jinping–Sunan HVDC scheme which was put into operation in December 2012. It also narrowly missed becoming the world’s first 800 kV HVDC line, with the first pole of the Yunnan–Guangdong project having been put into service 6 months earlier. It was also the world’s longest HVDC line when completed, although that record is also expected to be overtaken early in 2013 with the completion of the first bipole of the Rio Madeira project in Brazil.
