Grid connection of offshore wind farms

The large wind resources offshore can contribute a lot to reach the goal of regenerative energy supply. Constant wind for many hours a year and large free space are the main advantages. The challenges are offshore conditions and connecting the wind farms on land on large scale of power transmission. Sea cables are limited in power supply and in case of AC also in length. DC converter stations installed offshore are a challenge, too. The concentration of offshore wind before transmitting onshore will reduce the number of sea cable landing points. The gas insulated transmission line in a tunnel offers a practical solution. In a European Union feasibility study the possibilities have been studied and options are recommended.