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.
A transmission tower is a tall structure, usually a lattice tower made of steel that is used to support an overhead power line. In electrical grids, transmission towers carry high-voltage transmission lines that transport bulk electric power from generating stations to electrical substations, from which electricity is delivered to end consumers; moreover, utility poles are used to support lower-voltage sub-transmission and distribution lines that transport electricity from substations to electricity customers.
The Baltic Cable is a monopolar HVDC power line running beneath the Baltic Sea that interconnects the electric power grids of Germany and Sweden. Its maximum transmission power is 600 megawatts (MW).
The HVDC Gotland, on the Swedish east coast, was the first fully commercial static plant for high-voltage direct current transmission (HVDC) in the world.
The HVDC Volgograd–Donbass is a 475 kilometres (295 mi) long bipolar ±400 kV high voltage direct current powerline used for transmitting electric power from Volga Hydroelectric Station at Volgograd in Russia to Donbas in eastern Ukraine and vice versa.
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.
The Pylons of Messina are two free-standing steel towers, the Sicilian one in Torre Faro and the Calabrian one in Villa San Giovanni. They were used from 1955 to 1994 to carry a 220 kilovolt power line across the Strait of Messina, between the Scilla substation in Calabria on the Italian mainland at 38°14′42″N15°40′59″E and the Messina-Santo substation in Sicily at 38°15′57″N15°39′04″E.
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.
HVDC Leyte–Luzon is a high-voltage direct current transmission link in the Philippines between geothermal power plants on the islands of Leyte and Luzon.
An electrode line is used in some high-voltage direct-current (HVDC) power transmission systems, to connect the converter stations to distant ground electrodes. Many long-distance HVDC systems use sea or ground return for the DC neutral current since this is considerably cheaper than providing a dedicated metallic return conductor on an overhead wire or cable. The ground electrode is separated from the converter station so that current returning through the ground electrode does not cause corrosion of parts of the station in contact with the earth.
Maple Bay is a seaside community located in the Cowichan Valley of southern Vancouver Island, British Columbia, Canada. A narrow inlet and surrounded by smooth, pebbled beaches, Maple Bay is home to marine activity all year round. Maple Bay is a small town with a population of 2,640.
Parker Island is a roughly 400-acre (160 ha) island in the Southern Gulf Islands of British Columbia, Canada. It forms the western side of Montague Harbour, sheltering it from the strong wind gusts of Trincomali Channel. The island may be reached by floatplane, private boat, helicopter or water taxi; there is no public ferry service.
Sansum Narrows is a strait or channel between Vancouver Island (W) and Saltspring Island (E) in the Southern Gulf Islands region of British Columbia, Canada. The narrows are between Maple Bay and Tl’ulpalus.
The Saint Lawrence River HVDC Powerline Crossing is the crossing of Hydro-Québec's Quebec-New England HVDC transmission line over the Saint Lawrence River between Grondines and Lotbinière, Quebec, Canada. The crossing is remarkable, for being first implemented as an overhead crossing, and then later replaced by a cable tunnel. Hydro-Québec wanted to complete the transmission line in time, which was only possible with an overhead crossing of Saint Lawrence River. However, due to the negative visual impact of the large towers of the overhead crossing on the local populations of Grondines and Lotbinière, it was decided to build a cable tunnel under the river, although this made the project more expensive.
HVDC Ekibastuz–Centre is an unfinished HVDC transmission line between Ekibastuz in Kazakhstan and Tambov in Russia whose construction was started in 1978. It was planned to have a length of 2,414 kilometres (1,500 mi), which would have made it the longest powerline of the world with a maximum transmission rate of 6,000 MW and a transmission voltage of 750 kV between conductor and ground. For this line the erection of 4,000 pylons, most 41 metres (135 ft) tall, were required. Several hundred kilometres were built, including a Volga crossing on three 124 metres (407 ft) tall towers near Saratov, which were erected between 1989 and 1991. At Ekibastuz construction work at the terminal was started, while it was not the case at Centre substation, Tambov.
Zhoushan HVDC was the first HVDC scheme built in China and first put into service in July 2014.
The power grid of Vancouver Island is owned and operated by BC Hydro, and is connected with that of the Mainland of British Columbia by high voltage AC submarine cables, and formerly by a DC submarine cable system.
