Making connections at sea
As Europe’s offshore wind energy industry moves into deeper waters, the cables it uses to transfer the power produced to land are also evolving.
The traditional AC (Alternating Current) cables are being replaced by High Voltage Direct Current cables (HVDC). These offer several benefits, notably less power loss over long distances.
“The break-even distance for DC versus AC is about 80 kilometres”, Dr Dietmar Retzmann from Siemens Energy told Wind Directions.
Other benefits of HVDC are the greater amount of electricity that can be transmitted through a smaller cable, and the greater power flow controllability, which is well suited to a variable power source like the wind.
The main drawback to HVDC is the need for a sophisticated transformer system once the DC current reaches land and has to be changed into AC. The extra costs this entails, however, are expected to be made up for by the savings from reduced power losses.
For a more in-depth look at HVDC, see the latest issue of Wind Directions.