The Study of Control Strategy for VSC-HVDC applied in offshore wind farm and grid connection

To solve the problems of voltage fluctuation, flicker, harmonic and long distance transmission caused by offshore large scale wind farm(WF), a wind power integration scheme by using VSC-HVDC system has been proposed. The WF's voltage has kept in stable by the VSC-HVDC system's reactive power control in real time. There is little low-order harmonics and voltage fluctuation because the power has transmitted through the AC-DC-AC convert. Meanwhile, the transmission capacity has been improved by using HVDC technology and without environment problem because of submarine cable. The VSC-HVDC system's control strategy for the offshore WF integration has been described in detail and has been simulated in PSCAD. It can be seem from simulation result that the direct power control (DPC) and double loop control has good performance in VSC-HVDC system's control and the correctness and effectiveness of the integration scheme has also been verified.