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A Coordinated Control Strategy for AC Fault Ride-Though at Receiving End of Offshore Wind Farm Integration based on VSC-HVDC

For large-capacity offshore wind power based on VSC-HVDC, fault ride-through (FRT) is one of the most important problems to be solved. During the AC fault at the receiving end, the wind power system continues to provide wind power while the power transmission at the receiving end is blocked, which indicates that excessive active power would cause DC overvoltage risk. This paper first analyzed the topological structure and operating characteristics of a full bridge-dynamic braking system(FB-DBS). Combing the DBS, frequency increase method, and magnitude reduction method, a coordinated control strategy is proposed for offshore wind farms for fault ride-through(FRT). When the DC voltage exceeds the threshold value, FB-DBS is used to absorb the transient excessive active power of the DC links. Meanwhile, the wind turbine generator (WTG) would reduce the active power output by designed characteristics. By WTGs’ power reduction, FB-DBS rated capacity can be reduced effectively, which can achieve higher cost-efficiency, lower heat dissipation requirements and better FRT effects. Finally, a case study of a three-terminal VSC-HVDC for offshore wind power transmission is simulated in the PSCAD/EMTDC. The simulation results verify the effectiveness and superiority of the proposed control strategy.