CU is the designation of a line for high-voltage direct current (HVDC) transmission between the Coal Creek Station power plant south of Underwood, North Dakota at 47°22′24″N101°9′23″W / 47.37333°N 101.15639°W and the Dickinson converter station near Buffalo, Minnesota at 45°06′40″N93°48′36″W / 45.11111°N 93.81000°W .
The designation most likely refers to two Minnesota-based power generation/transmission cooperatives that originally partnered to build the Coal Creek plant and associated line - Cooperative Power Association and United Power Association, which later merged to become Great River Energy. Great River Energy recently announced that the mine-mouth plant that supplies this line, Coal Creek Station, will be decommissioned in 2022, unless another entity steps up to acquire (and continue operating) the plant, leaving the future of this line in doubt.
The CU project controversy in 1978 and 1979 was a result of protests by farm landowners in the path of the CU line right of way.
The CU line, which went in service in 1978, can transfer an electrical power of 1,000 megawatts at a symmetrical transmission voltage of 400 kV. An overhead line connection 436 miles (710 kilometers) long is used, with two conductors per pole. Thyristor static inverters are used. [1]
Southeast of Wing, North Dakota, at 47°02′48″N100°05′49″W / 47.04667°N 100.09694°W CU crosses Square Butte, another HVDC powerline. This is the only crossing point of two HVDC overhead powerlines in the Western hemisphere.
The ground return electrode line at Coal Creek Station uses the towers of the AC line between 47°22′28.01″N101°9′47.65″W / 47.3744472°N 101.1632361°W and 47°22′43.03″N101°10′4.94″W / 47.3786194°N 101.1680389°W as support before it ends at 47°24′53.2″N101°13′40.81″W / 47.414778°N 101.2280028°W .
The electrode line at Dickinson converter plant runs on the towers of the main line until a tower at 45°9′27.81″N94°2′15.06″W / 45.1577250°N 94.0375167°W . From this tower it runs on a line on 4 poles until its endpoint situated at 45°9′33.73″N94°2′23.74″W / 45.1593694°N 94.0399278°W .
A transmission tower, also known as an electricity pylon or simply a pylon in British English and as a hydro tower in Canadian English, is a tall structure, usually a steel lattice tower, used to support an overhead power line.
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.
HVDC Vancouver Island is a de-energized high-voltage direct current interconnection between Arnott Substation (ARN) in Delta, British Columbia at 49°5′31″N123°2′31″W on the Canadian mainland, and the Vancouver Island Terminal (VIT) in Duncan, British Columbia on Vancouver Island at 48°49′39″N123°42′55″W. It went into operation in 1968 and was extended in 1977. HVDC Vancouver Island consists of three overhead line sections with a total length of 42 kilometres and two submarine cable sections with a length of 33 kilometres. Pole 1 ceased operation in 2014, and Pole 2 ceased operation in 2016. The infrastructure remains in place and portions may be re-used in the future.
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 3,100 megawatts, 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 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.
Path 27, or the Intermountain Power Project DC Line, or the Southern Transmission System is a HVDC transmission line that carries electricity from the Intermountain Power Plant near Delta, Utah to the city of Los Angeles via the Adelanto Converter Station in Adelanto, California. It is owned and operated by the Intermountain Power Agency, a large cooperative primarily owned by the Los Angeles Department of Water and Power (LADWP) (50%) along with five other Los Angeles area cities (25%) and 30 small Utah municipalities.
Fenno–Skan is the designation of the high voltage direct current transmission between Dannebo in Sweden and Rauma in Finland.
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.
The HVDC Three Gorges – Changzhou is an 940-kilometre (580 mi) long bipolar HVDC transmission line in China for the transmission of electric power from the Three Gorges power plant to the area of Changzhou.
The HVDC Three Gorges – Guangdong is a 940 kilometre-long bipolar HVDC transmission line in China for the transmission of electric power from the Three Gorges power plant to the area of Guangdong. The powerline went into service in 2004. It runs from the static inverter station Jingzhou near the Three Gorges power plant to the static inverter plant Huizhou near Guangdong. The HVDC Three Gorges-Guangdong is a bipolar 500 kV powerline with a maximum transmission power rating of 3,000 megawatts.
Wolmirstedt substation is a large node in the power grid of former East Germany and termination of Germany's longest powerline, running from Lubmin nuclear power station to Wolmirstedt substation.
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.
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 CU project controversy involved years of protest against a proposed high-voltage direct current powerline that was erected on the property of hundreds of farmers in west central Minnesota in the late 1970s. The electrical cooperatives Cooperative Power Association (CPA) and United Power Association (UPA) proposed construction of the powerline, which was part of a larger project that also involved the construction of an electrical generating station and coal mine.
HVDC Tian–Guang is a bipolar 500 kV HVDC system used for transmitting power generated at Tianshengqiao Hydroelectric Plant to Guangzhou. HVDC Tian–Guan, which was built by Siemens and inaugurated in 2001 is capable of transmitting a maximum power of 1,800 MW.
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.