Thyristor-Based Multiport Hybrid DC Circuit Breaker for Multiterminal DC Grid Protection

Since the multiport hybrid dc circuit breaker (HCB) can share the expensive main breaker among multiple adjacent lines, it is considered as a more cost-efficient choice than typical HCB to isolate the dc-side fault in the large-scale multiterminal dc grid. However, the existing multiport HCBs still require a large number of fully controlled semiconductor switches (FCSSs), such as insulated gate bipolar transistors and integrated gate-commutated thyristors. Considering the high unit price and weak current turn-off capability of the FCSS, the total costs of the multiport HCBs are still high. Compared with the FCSS, the thyristor has significantly lower unit price, larger surge current withstanding capability, and higher reliability. Therefore, in this article, a thyristor-based multiport hybrid dc circuit breaker (T-MHCB) is proposed to replace the FCSS-based MHCB, which has close action speed but significantly lower costs. Extensive simulations and experiments have verified the effectiveness of the proposed T-MHCB. Besides, the performance comparison of the T-MHCB with existing solutions is elaborated.