Electric power transmission through interconnectors using high-voltage direct-current (HVDC) involves usually two converter stations and a transmission line. Generally overhead lines are used, but an important class of HVDC projects use submarine power cables. A back-to-back station has no transmission line and joins two separate AC grids at a single point. Historical HVDC systems used the Thury system of motor-generators but these have all been made obsolete by later developments such as mercury-arc valves (now also obsolete), thyristors, and IGBT power transistors.
Built as 250kV 600MW link Paralleled to operate at 270 kV as positive pole with HVDC Inter-Island 2 in 1992. Partially decommissioned in 2007, fully decommissioned in August 2012. Supplier: ABB
Negative pole, operates in bipole configuration with HVDC Inter-Island 3 (previously HVDC Inter-Island 1) Restricted to 500MW due to cable rating. Supplier: ABB
From north bank of Three Gorges to Zhengping, 200km from Shanghai in the East grid Supplier: ABB, Siemens. Sharing of grounding electrode at Chujiahu with HVDC Hubei-Shanghai
Power line shares pylons of HVDC Gezhouba - Shanghai in most part of its track, sharing of grounding electrode at Chujiahu with HVDC Shanghai-Changzhou
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Nanhui Wind Farm Integration
China
China
8.4 (8.4/0)
30
18
2011
IGBT
Supplier: C-EPRI Electric Power Engineering Co., Ltd
SEPRI (Electric Power Research Institute, China Southern Power Grid) is technically responsible for the entire project. Multiple suppliers are involved: three different VSC HVDC valve suppliers, two different HVDC land/sea cable suppliers and three different control & protection system/equipment suppliers.
Opposite pole of Kingsnorth - Beddington. Cable wholly underground except for Thames crossing - crossed on upstream side of Putney District line railway bridge
2 As of 9 December 2015, LitPol Link started trial operations.[179] 3 Caithness Moray HVDC serves a number of renewable energy sources in the north of Scotland - see map[180] 4 Contracts due to be placed in 2016. 5 Elia says construction expected to start in late 2017. 6 Date is that quoted to support the Shetland Wind Farm that SSE is a part investor in.[181] 7 Decision on project expected in 2017 following consultation - see SSE PD reference.
Transmission voltage ±400 kV until 1984 Maximum transmission power 1440 MW until 1982 From 1982 to 1984 1600 MW From 1984 to 1989 2000 MW Merc replaced by Thyr in 2004 Original supplier: ASEA, General Electric In 1989 upgraded by ABB In 2004 upgraded by ABB and Siemens
Used the largest mercury arc rectifiers ever built Original supplier: English Electric. In 1992/1993, Pole 1 upgraded to Thyr by Alstom. In 2004, Pole 2 upgraded to Thyr by Siemens.
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 Moyle Interconnector is a 500megawatt (MW) HVDC link between Scotland and Northern Ireland, running between Auchencrosh in Ayrshire and Ballycronan More in County Antrim. It went into service in 2001 and is owned and operated by Mutual Energy.
NorNed is a 580-kilometre (360 mi) long high-voltage direct current submarine power cable between Feda, Norway and the seaport of Eemshaven in the Netherlands, which interconnects both countries' electrical grids. It was once the longest submarine power cable in the world. Budgeted at €550 million, and completed at a cost of €600m, the NorNed cable is a bipolar HVDC link with a voltage of ±450 kV and a capacity of 700 MW. NorNed is a joint project of the Norwegian transmission system operator Statnett and its Dutch counterpart TenneT. The cable system itself and the two converter stations were produced by ABB.
A submarine power cable is a transmission cable for carrying electric power below the surface of the water. These are called "submarine" because they usually carry electric power beneath salt water but it is also possible to use submarine power cables beneath fresh water. Examples of the latter exist that connect the mainland with large islands in the St. Lawrence River.
The East–West Interconnector is a 500MW high-voltage direct current submarine and subsoil power cable from 2012 which connects the Irish and British electricity markets, between Dublin and the Wales/England border. The project was developed by the Irish national grid operator EirGrid.
NordLink is a subsea 1,400 megawatt (MW) HVDC power cable between Norway and Germany, opened in May 2021. The over 500 kilometres (310 mi) long cable operates at a voltage of 500 kV DC.
TenneT is a transmission system operator in the Netherlands and in a large part of Germany.
Energinet is the Danish national transmission system operator for electricity and natural gas. It is an independent public enterprise owned by the Danish state under the Ministry of Climate and Energy. Energinet has some 1150 employees, and its headquarters are located in Erritsø near Fredericia in Jutland. The gas division is located in Ballerup near Copenhagen.
BritNed is a 1,000MW high-voltage direct-current (HVDC) submarine power cable between the Isle of Grain in Kent, the United Kingdom; and Maasvlakte in Rotterdam, the Netherlands.
The North Sea Link is a 1,400MW high-voltage direct current submarine power cable between Norway and the United Kingdom.
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.
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 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.
COBRAcable is a ±320 kV, 700 MW HVDC submarine power cable pair between Eemshaven, the Netherlands and Endrup near Esbjerg, Denmark. The cable is jointly owned by Energinet.dk and TenneT. Its purpose is to improve the European transmission grid and thus increase the amount of variable wind power in the system while improving supply reliability. Its 700 MW capacity corresponds to an annual transmission capacity of 6.1 TWh.
Viking Link is a 1,400 MW HVDC submarine power cable between the United Kingdom and Denmark, which was completed in 2023. As of 2024, it is the longest land and subsea HVDC interconnector in the world. The project is a cooperation between British National Grid and Danish Energinet.
Nemo Link is a 1,000MegaWatt HVDC submarine power cable between Richborough Energy Park in Kent, the United Kingdom and Zeebrugge, Belgium. The project is a joint venture between British National Grid and Belgian Elia. The 400kV electrical interconnector is the first between the two countries, with an annual transmission capacity of 8.76TWh. The link has been fully operational since 31 January 2019, and has transported 29 TWh during its first 5 years; 24.75 TWh to the UK and 4.25 to Belgium with an availability above 99%.
Kriegers Flak is a 605 MW offshore wind farm in the Baltic Sea on the Danish part of the reef of the same name. It forms part of a new 400 MW interconnector between Denmark and Germany.
EuroAfrica Interconnector is a planned HVDC interconnector and submarine power cable between the Greek, Cypriot, and Egypt power grids. The Interconnector is an energy highway bridging Africa and Europe. It will have a capacity to transmit 2,000 megawatts of electricity in either direction. Annual transmission capacity will be rated at 17.5 TWh, much more than the annual production at the Aswan Dam power stations. President of Egypt Abdel Fattah el-Sisi, President of Cyprus Nicos Anastasiades and Prime Minister of Greece Kyriakos Mitsotakis, issued a joint declaration at the conclusion of the 7th Trilateral Summit, held in Cairo on October 8, 2019, in which they expressed their desire to continue strengthening their cooperation in matters of energy. In particular, the joint declaration by the three leaders stated they recognised the importance of establishing an electrical grid between Egypt, Cyprus and Greece, building on the framework agreement between the Egyptian Electricity Holding Company and the Euro Africa Interconnector Company on 22 May 2019.
↑ "Mutual Energy". Mutual Energy. Archived from the original on 9 January 2016. Retrieved 31 December 2015.
1 2 3 4 5 6 7 8 Working Group on HVDC and FACTS Bibliography and Records (2008-07-07). "HVDC PROJECTS LISTING"(PDF). IEEE Transmission and Distribution Committee. Archived from the original(PDF) on 2008-12-15. Retrieved 2008-12-19.
↑ "REE on INELFE". Spain-France underground interconnection. Red Eléctrica da España. Archived from the original on 20 January 2016. Retrieved 5 January 2016.
↑ "INEFE ready for testing". HVDC link between France and Spain. Siemens. Archived from the original on 20 January 2016. Retrieved 5 January 2016.
↑ "Nemo Link". Nemo Link. Archived from the original on 10 January 2016. Retrieved 31 December 2015.
↑ "Siemens re Nemo Link". Siemens wins major HVDC order to connect British and Belgian power grid. Siemens. Archived from the original on 20 January 2016. Retrieved 13 January 2016.
↑ "ALEGrO Project". ALEGrO Project. Elia. Archived from the original on 30 January 2016. Retrieved 24 January 2016.
↑ "EU PCI 2013 - see Cyprus"(PDF). EU Projects of Common Interest. European Commission. Archived(PDF) from the original on 14 January 2016. Retrieved 24 January 2016.
↑ Westerweller T., Friedrich, K., Armonies, U., Orini, A., Parquet, D., Wehn, S., Trans Bay cable – world's first HVDC system using multilevel voltage-sourced converter, CIGRÉ session, Paris, 2010, paper reference B4-101
↑ "NECPL Submarine Cable Installation"(PDF). New England Clean Power Link: Project Development Portal. TDI New England. 2014-10-09. Archived(PDF) from the original on 2016-01-20. Retrieved 2014-12-30.
↑ "SOO Green HVDC Link". SOO Green HVDC Link. Direct Connect Development Company. 2020. Archived from the original on 2021-06-27. Retrieved 2021-06-15.
Vijay K. Sood (31 May 2004). HVDC and FACTS Controllers: Applications Of Static Converters In Power Systems. Springer-Verlag. p.2. ISBN978-1-4020-7890-3.
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