Feasible protection strategy for HVDC system by means of SFCL and passive resonance DC breaker

The key obstacle in implementing high-voltage direct current (HVDC) grid, which is considered as the future of power grid, is the absence of effective DC circuit breaker (DCCB). At present, HVDC grid could be based on half-bridge (HB) or full-bridge (FB) voltage source converter (VSC). Among these two converter topologies, FB topology has an advantage of reverse current blocking at a much higher cost compared to HB technology and still requires a DCCB for isolating the faulty line. Therefore, HB technology is more realistic to implement HVDC grid economically if DC fault current could be controlled more effectively. In this respect, this article suggests feasible fault protection strategy based on superconducting fault current limiter (SFCL) and passive resonance circuit breaker (PRCB) which could be applied effectively to HB system. To evaluate the performance of suggested protection scheme, comparative study of full-bridge modular multilevel converter (FB-MMC) protection was performed. In addition, the process to determine the optimal range for quenching resistance of SFCL was also investigated. Consequently, the authors’ suggested protection scheme has shown remarkably improved fault current limiting and interruption performance compared to FB-MMC protection scheme.