Research on a Novel DC Circuit Breaker Based on Artificial Current Zero-Crossing

Modular multilevel converter-based high voltage direct-current (MMC-HVDC) transmission has developed rapidly because of its flexibility, reliability and efficiency. DC circuit breaker (DCCB) is one of the key equipments to ensure the safe and stable operation of MMC-HVDC power grids. In this paper, we investigate a novel topology of DC circuit breaker based on artificial current zero-crossing. The proposed DC circuit breaker can effectively limit the magnitude and rise rate of fault current at the converter station side and reduce the impact of DC fault on the converter devices. The principle and operation sequence of this topology are described. Meanwhile, the breaking process of the DC fault is analyzed theoretically and the considerations for parameter design are presented. Finally, the system model of DC circuit breaker and a four-terminal MMC-HVDC test system are built in PSCAD/EMTDC. The simulation results show that the proposed DC circuit breaker is effective for quick breaking after fault.