A Novel Hybrid DC Circuit Breaker Based on Precharged Capacitors

Low impedance in DC grid leads to sharp increase of fault current, which may do damage to power grid security, once short-circuit fault occurs. DC circuit breaker technology has been becoming one of the most essential factors contributing to DC power grid. Hybrid DC circuit breaker (DCCB) is prominent in DC grid due to its fast working speed and high reliability. However, the existing hybrid DCCB schemes suffer from high cost and current-limiting shortage. To solve these problems, this paper proposes a novel hybrid DCCB based on pre-charged capacitors, which can not only suppress short current and cut off the fault line timely, but also reduce the cost of breaker greatly. Operating principle, parameter design and control strategy are demonstrated in detail. The economic and technical comparison between the proposed and existing schemes is carried out. The effectiveness and stability of the novel DCCB are validated by the simulation in PLECS.