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Multiport Hybrid DC Circuit Breaker with Reduced Fault Isolation Time

The typical hybrid dc circuit breaker (HCB) has the advantages of low operating loss and fast action speed, which is an ideal design scheme for dc circuit breakers (DCCBs). However, since the main breaker (MB) of the typical HCB requires many semiconductor switches, it is extremely expensive and difficult to be applied to the multi-terminal dc (MTdc) grid on a large scale. Besides, due to the large current-limiting inductors (CLIs) in the MTdc grid configured to suppress the fault current, their stored energy should be dissipated, thereby leading to the extension of the fault isolation for several milliseconds. In order to solve these problems, a multiport hybrid dc circuit breaker (MHCB) is designed in this paper, which greatly reduces the manufacturing costs by sharing expensive MB among multiple lines at a dc bus. In addition, by bypassing the CLI in the energy dissipation stage, the implementation cost of the arresters in the MB and the total fault isolation time are both greatly reduced. Extensive simulations verify the feasibility of the proposed MHCB.