Optimized Circuit Breaker for DC Grids

Abstract:
The advantages of DC grids are well known from numerous scientific studies and practical pilot plants. Apart from many benefits, there are also challenges like interrupting rapidly rising fault currents at the absence of current zero crossing. Thus, DC circuit breakers (DCCBs) play a significant role in terms of feasibility, safe operation, reliability and stability for DC grids. In this paper, the critical faults in DC grids are depicted and the requirements for a DCCB are derived. Various types of switching elements are examined and their suitability for use in a DCCB are evaluated. An optimized DCCB is proposed, where different types of switching elements are combined in one device in order to get the optimal trade-off in terms of fast response, galvanic isolation, power loss, lifetime, size and cost.