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 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).
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.
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 Rihand–Delhi is a HVDC connection between Rihand and Dadri in India, put into service in 1990. It connects the 3,000 MW coal-based Rihand Thermal Power Station in Uttar Pradesh to the northern region of India. The project has an 814 kilometres (506 mi) long bipolar overhead line. The transmission voltage is 500 kV and the maximum transmission power is 1,500 megawatts. The project was built by ABB.
Murraylink is an Australian high voltage direct current electricity transmission link between Berri in South Australia and Red Cliffs in Victoria, connecting the two state electricity grids. Murraylink was commissioned in 2002 and is believed to be the world's longest underground transmission system and cost more than A$177 million. It was built by TransEnergie Australia, a subsidiary of Hydro-Québec. It was sold to the Australian Pipeline Trust in March 2006 for A$153 million. In December 2008 ownership of Murraylink was transferred to the newly formed Energy Infrastructure Investments Group, while APA continued as the operator. The ownership of EII is APA with 19.9%, with the balance with Japan-based Marubeni Corporation with 49.9% and Osaka Gas with 30.2%.
BritNed is a 1,000 MW high-voltage direct-current (HVDC) submarine power cable between the Isle of Grain in Kent, the United Kingdom; and Maasvlakte in Rotterdam, the Netherlands.
HVDC DolWin1 is a high voltage direct current link built to transmit offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters are used and the total cable length is 165 km. The project was built by ABB and was handed over to its owner, TenneT, in July 2015, the fifth such project to be completed in Germany in 2015.
HVDC HelWin1 is a high voltage direct current (HVDC) link built to transmit Offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters are used and the total cable length is 130 km. The project was completed and handed over to its owner, TenneT, in February 2015.
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 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.
HVDC BorWin2 is a high voltage direct current (HVDC) link built to transmit offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters are used and the total cable length is 200 km. The project was completed by the Siemens/ Prysmian consortium and handed over to its owner, TenneT, in January 2015, becoming the first such project to be completed.
HVDC HelWin2 is a high voltage direct current (HVDC) link built to transmit offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters with DC ratings of 690 MW, ±320 kV are used and the total cable length is 130 km. The project was built by the Siemens/Prysmian consortium with the offshore platform built by Heerema in Zwijndrecht, Netherlands. The topside measures 98 m x 42 m x 28 m and weighs 10200 tonnes. The project was handed over to its owner, TenneT, in June 2015, the fourth such project to be completed in 2015.
HVDC SylWin1 is a high voltage direct current (HVDC) link to transmit offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters with DC ratings of 864 MW, ±320 kV are used and the total cable length is 205 km. The project is similar to the HVDC BorWin2 project but has slightly higher power and voltage ratings. It is being built by the Siemens/ Prysmian consortium and was handed over to its owner, TenneT, in April 2015.
HVDC DolWin2 is a high voltage direct current (HVDC) link to transmit offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters with DC ratings of 900 MW, ±320 kV are used and the total cable length is 135 km. The project is similar to the HVDC DolWin1 project but has a slightly higher power rating and uses a different design of offshore platform. The platform was designed by Norwegian company Aibel and built by Drydocks World in Dubai and transported to Europe in the summer of 2014 to be fitted out at the Aibel yard in Haugesund in Norway. The platform, which is of a floating, self-installing design not previously used in an HVDC project, sailed out from Haugesund on 1 August 2015 and was installed in the North Sea ten days later.
HVDC DolWin3 is a high voltage direct current (HVDC) link to transmit Offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters with DC ratings of 900 MW, ±320 kV are used and the total cable length is 160 km.
HVDC BorWin3 is a high voltage direct current (HVDC) link under construction to transmit offshore wind power to the power grid of the German mainland. The project differs from most HVDC systems in that one of the two converter stations is built on a platform in the sea. Voltage-Sourced Converters with DC ratings of 900 MW, ±320 kV are used and the total cable length is 160 km. The project is the most recent of the German offshore HVDC projects to be awarded. It is being built by the Siemens/ Petrofac consortium with the offshore platform contract awarded to Drydocks World in Dubai. The project is expected to be handed over to its owner, TenneT, in 2019. The project started power transmission in August 2019. TenneT took control of operations in February 2020.
