Multi-port hybrid DC circuit breaker with shared main breaker circuit

Hybrid DC circuit breaker (HCB) is an effective solution to realize fault isolation when DC side fault occurs in DC grid. However, the main breaker (MB) in the conventional two-port HCB requires a large number of insulated gate bipolar transistors (IGBTs) in series, which raises the cost. With the expansion of the DC grid, a single DC bus in the multi-terminal DC grid is usually connected to numerous DC lines. In order to ensure absolute selectivity of protection, the two-port HCB needs to be installed on each DC line, which is extremely costly. Additionally, a crucial assurance for the fault isolation of the HCB is the successful opening of the ultra-fast disconnector (UFD). Nevertheless, the majority of the existing HCBs ignore remedial actions in the case of UFD failure. In response to the above problems, this article proposes a multi-port HCB (MPCB) with a shared MB. The proposed MPCB integrates n HCBS on the DC bus to become an n-port HCB sharing two MBs. The two MBs are able to achieve fault isolation on either line or the DC bus, guaranteeing fault current interruption performance while significantly reducing economic costs. Moreover, to avoid the problem of fault isolation failure caused by UFD failure, the proposed MPCB is equipped with UFD failure protection function by adding a UFD failure auxiliary switch.