A Novel DC Energy Dissipation Topology and Control Method

A DC energy dissipation arm(EDA) structure with coupled transformer is proposed to solve the problem of DC voltage rise caused by AC voltage sag fault in offshore wind power generation systems; The proposed method reduces the cost of the high-voltage wall bushing and improves the economy of the equipment by reducing the voltage at both ends of the energy dissipation resistors; According to the calculation, the cost of high-voltage wall bushing can be reduced by 23 ~ 28% under 230 kV condition; The IGBT overvoltage caused by inconsistent turn-off time was successfully avoided by connecting IGBT and MOV in parallel, and reduce the volume of converter station caused by excessive capacitance; The proposed control strategy successfully dissipates surplus energy. At the same time, a fault operation control strategy is proposed, in which the device can cooperate with the receiving end converter(REC)in the case of partial IGBT faults and continue to operate at a specific power.