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.

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Converter technology: Line status: {{legend|#FFFFFF|Existing}} {{legend|#BFBFFF|Under construction}} {{legend|#EFFFBF|Planned}} {{legend|#EFBFBF|Decommissioned}}

Africa

Australia and Oceania

Asia

Europe

2 As of 9 December 2015, LitPol Link started trial operations. 3 Caithness Moray HVDC serves a number of renewable energy sources in the north of Scotland - see map 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. 7 Decision on project expected in 2017 following consultation - see SSE PD reference.

North America

South America

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Maps

Europe

[{{legend|#f80e34|Existing}} {{legend|lime|Under construction}}

{{legend|#0e1ef8|Options under consideration}} HVDC interconnections in Europe | upload.wikimedia.org/wikipedia/commons/6/60/HVDC///Europe///annotated-2019.svg]

Sources