Great interest has been developed in renewable energy systems to mitigate the greenhouse effect. In Western Europe, therefore, the focus is on wind power and especially offshore sites, due to increased energy production, longer service life and lack of adequate wind turbine sites on the mainland . A DC cable is the preferred option when connecting large offshore wind farms to the grid. The use of Dc cables was enabled by the new HVDC transmission technology that uses voltage converters.
The offshore wind farms being built today use an AC connection to the shore and the distances to the shore are also quite moderate. This document describes three different solutions with a direct current connection and compares the cost and loss of a DC system with a traditional AC system that is used as a reference. DC systems will be competitive solutions in ten years and have several advantages compared to an AC system. This document includes several reasons for selecting a DC cable is the preferred option when connecting large offshore wind farms, to the grid.