Fault Recovery Overvoltage Suppression in DC System Based on SFCL

Aiming at the overvoltage during fault recovery of DC system, this paper studies overvoltage generation mechanism and puts forward an overvoltage suppression method based on superconducting fault current limiter (SFCL) matching design. Based on the equivalent circuit of the system after fault isolation, the generation mechanism and influencing factors of fault recovery overvoltage are analyzed. It is found that the root cause of fault recovery overvoltage is the inconsistent voltage drop rate of each converter during the fault. Therefore, this paper puts forward a method to match SFCL of each converter’s outlet, so that the voltage drop rate of each converter during the fault is almost the same, and inhibiting the fault recovery overvoltage could be achieved. Finally, the simulation results of PSCAD/EMTDC show that the proposed method has good overvoltage suppression effect.