A Dual-Bridge Hybrid DC Circuit Breaker

Various DC circuit breakers (DCCBs) have been widely proposed for the DC fault protection of high-voltage direct-current (HVDC) grids. In recent years, hybrid DCCBs (HCBs) have been paid significant attentions due to their features of low power losses and fast dynamic response. However, several aspects regarding the design of HCB should be further addressed. For instance, the requirement of deploying a large surge arrester to dissipate the large fault current energy should be further addressed and the strategy to perform zero-voltage switching (ZVS) of semiconductor devices during the post-fault restoration processes should be investigated. In this paper, a dual-bridge hybrid DC circuit breaker (DB-HCB) with freewheeling diode branches is proposed to address the above issues. The operation principle of the proposed DB-HCB for pole-to-ground and pole-to-pole faults is presented. Compared with other HCBs, the capacity of the surge arrester is obviously reduced, so that the capital cost and volume of the proposed DB-HCB is decreased. Moreover, the ZVS is implemented during the post-fault restoration processes. Simulation results in PSCAD/EMTDC are given to validate the effectiveness of the proposed DB-HCB.