| HVDC Gotland | |
|---|---|
 Map of HVDC Gotland | |
| Location | |
| Country | Sweden |
| To | Gotland |
| Construction information | |
| Commissioned | 1954 (Gotland 1) 1983 (Gotland 2) 1987 (Gotland 3) |
| Technical information | |
| Power rating | 20MW (Gotland 1) 150MW (Gotland 2) 150MW (Gotland 3) |
| DC voltage | 100kV (Gotland 1) 150kV (Gotland 2) 150kV (Gotland 3) |
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 first HVDC Gotland link (Gotland 1) went into service in 1954. It could transfer 20 megawatts over a 98-kilometer-long submarine cable between Västervik on the mainland and Ygne on the island of Gotland, with a voltage of 100 kV. As a static inverter, Mercury arc valves were used.
In 1970 the service was re-engineered to transmission capacity of 30 megawatts at a voltage of 150 kV by using the first thyristor module for HVDC applications.
However even this capacity was not high enough and in 1983 a new monopolar link, HVDC Gotland 2 with a transmission capacity of 130 MW and a transmission voltage of 150 kV was established. It consists of a 92.9 kilometers long cable with a single copper conductor of 800 mm2 cross section, from which 92 kilometres are submarine and 0.9 kilometres underground. Beside this, HVDC Gotland 2 has a 6.6 kilometres long overhead powerline section between Västervik static inverter plant and the Swedish Coast. It has 2 Aluminium conductors each with a cross section of 910 mm2, which are installed on wooden poles - perhaps the only HVDC powerline using such poles.
In 1987 HVDC Gotland 3, a further monopolar link, with a transmission capacity of 130 MW and transmission voltage of 150 kV was installed. It consists of a 98 kilometers long cable with a single copper conductor of 800 mm2 cross section. 92 kilometres of this cable are laid in the sea and 6 kilometres underground on land.
The grounding electrode of the Västervik Inverter Station is situated at Almvik on Östra Eknö, that of Ygne Inverter Station at Gravfält. Both electrodes are used for Gotland 2 and Gotland 3 and are situated in sea-water filled basins close to the sea. At Almvik there are 2 such basins, while Gravfält uses only one. The basin design of the electrodes prevents fishes from getting too close to the electrodes, which may harm them. The Almvik electrode is connected with Västervik Inverter Station by an 18.95 kilometres long line with 4 overhead line and 3 submarine cable sections for strait crossings. The overhead line sections, which have a total length of 17 kilometres are installed on wooden poles and consist of 2 Aluminium conductors each with 910 mm2 cross section. The total length of the cable sections amounts to 1.95 kilometres and consist of 2 cables each with 1000 mm2 cross section. The connection between Ygne Inverter Station and Gravfält Electrode has a length of 12.75 kilometres. It consists of a 12 kilometres long overhead line on wooden poles, which uses 2 Aluminium conductors each with 910 mm2 cross section and a 0.75 kilometres long underground cable consisting of 2 Aluminium conductors each with 1000 mm2 cross section.
| Site | Coordinates |
|---|---|
| Västervik HVDC Static Inverter | 57°43′41″N16°38′51″E / 57.72806°N 16.64750°E |
| Händelöp HVDC Gotland 2 Cable Terminal | 57°41′07″N16°42′47″E / 57.68528°N 16.71306°E |
| Lilla Nävelsvik Electrode Line Terminal | 57°40′57″N16°38′22″E / 57.68250°N 16.63944°E |
| Narsvik Overhead Electrode Line Terminal | 57°40′41″N16°38′19″E / 57.67806°N 16.63861°E |
| Grönvall Overhead Electrode Line Terminal | 57°38′54″N16°37′25″E / 57.64833°N 16.62361°E |
| Grytsholmen Overhead Electrode Line Terminal | 57°38′42″N16°37′21″E / 57.64500°N 16.62250°E |
| Hamudden Overhead Electrode Line Terminal | 57°36′29″N16°39′33″E / 57.60806°N 16.65917°E |
| Västerbofjärden Overhead Electrode Line Terminal | 57°36′10″N16°40′25″E / 57.60278°N 16.67361°E |
| Almvik Electrodes | 57°34′32″N16°41′49″E / 57.57556°N 16.69694°E ; 57°34′29″N16°41′50″E / 57.57472°N 16.69722°E |
| Ygne HVDC Static Inverter | 57°35′13″N18°11′44″E / 57.58694°N 18.19556°E |
| Gravfält Electrode | 57°30′52″N18°6′35″E / 57.51444°N 18.10972°E |
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.
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 Kontek HVDC is a 170-kilometre (110 mi) long, monopolar 400 kV high-voltage direct current cable between Germany and the Danish island Zealand. Its name comes from "continent" and the name of the former Danish power transmission company "Elkraft", which operated the power grid on the Danish islands Lolland, Falster and Zealand and had the abbreviation "ek". As of today, the cable is operated by Energinet.dk in Denmark and 50Hertz Transmission GmbH in Germany.
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).
Konti–Skan is the name of high-voltage direct-current transmission line between Denmark (DK1) and Sweden (SE3).
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.
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 3.1 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.
Skagerrak is the name of a 1,700 MW high-voltage direct current (HVDC) transmission facility between Tjele (Denmark) and Kristiansand (Norway). It is owned and operated by Statnett in Norway, and Energinet in Denmark. The lines connect the hydroelectric-based Norwegian grid and the wind and thermal power-based Danish grid. In operation it enables more renewable energy in the energy mix, and more efficient use of electricity.
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 Italy–Greece is a monopolar submarine power cable link between Italy and Greece with a maximum transmission power of 500 megawatts. It went in service in 2001. The HVDC Italy–Greece begins in the static inverter plant Galatina situated at 40°9′53″N18°7′49″E in Italy and is implemented in its first 43 kilometres (27 mi) as underground cables. Then it crosses the Ionian Sea as a 160 kilometres (99 mi) long submarine cable. It reaches shore just a few kilometres south of Albanian border at 39°41′00″N20°1′09″E, where the 110 kilometres (68 mi) long overhead line to Arachthos static inverter station situated at 39°11′00″N20°57′48″E starts. The cathode is implemented as bare copper wire on the Italian site, the anode is installed in a bay in Greece at 39°40′28″N20°4′05″E.
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.
The HVDC Haenam–Cheju is a 101 kilometer long HVDC submarine cable connection between the Korean Peninsula and the island of Jeju in South Korea, which went into service in 1996. The connection is bipolar, consisting of two 180kV cables with a maximum transmission power of 300 megawatts.
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.
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 Talcher–Kolar HVDC system, otherwise known as the East–South interconnection II is a 1450 km HVDC transmission connection between the eastern and southern regions in India connecting four states namely Odisha, Andhra Pradesh, Tamil Nadu and Karnataka. The system has a transmission voltage of ±500 kV and was originally put into service in March 2003, with a rated power of 2000 MW. In 2007 the scheme was upgraded to 2500 MW.
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