High-Power DC Distribution Systems for Offshore Wind Farms

Abstract:
During the past decade the share of renewable energy sources in power systems has increased significantly. Especially, wind power is becoming an important energy supplier in future energy systems. Currently, one promising solution for increasing drastically the installed wind power are offshore wind farms. Because of the high installation cost only large farms are considered, with power levels of several 100 MW placed up to 100 km out in the sea. Considering the interconnection of offshore wind farms, new technologies must be investigated. One promising solution for an interconnection is a DC distribution system which is also discussed for new (onshore) medium-voltage distribution systems. In contrast to standard AC systems new components have to be developed to enable connection to high-power DC grids. This paper will focus on two major components for future offshore DC grids, on the one hand a hybrid circuit breaker will be presented, which is able to switch off high DC currents and on the other hand a high power DC/DC converter will be presented, which is able to step-up DC voltages within the grid.