A Novel Controllable Oscillating Homopolar Coupling DC Circuit Breaker for VSC-Based DC Grids

The DC circuit breaker (DCCB) is one of the key devices to ensure the stable operation of VSC-based DC grids. Compared to solid-state and hybrid DC circuit breakers, mechanical DC circuit breakers have the advantages of low on-state losses and good economics. However, existing mechanical DC circuit breakers still suffer from problems such as high voltage level of pre-charging system, inability to achieve continuous interruption, and poor economics when applied to high voltage levels. To address these problems, a novel controllable oscillating homopolar coupling DC Circuit Breaker (COHC-DCCB) is proposed in this paper. Firstly, the mathematical model of the controllable oscillating circuit is constructed, and its oscillation mechanism is analyzed. Then, the operation principle of the proposed COHC-DCCB is described. Finally, the effectiveness and feasibility of the proposed COHC-DCCB is verified by extensive simulations with PSCAD/EMTDC.