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The hybrid dc circuit breaker is one of the most promising dc circuit breakers (DCCBs). However, its cost is relatively high, and the completion of its fault isolation is significantly delayed because of the large current limiting inductors configured in the multiterminal dc grid. Besides, due to the utilization of overhead lines, the probability of temporary faults is much increased, which means there is a great possibility that the power supply can be rapidly restored by reclosing DCCBs. However, the temporary faults must be distinguished from the permanent faults before the reclosing operation to avoid damaging the fragile power electronic equipment. Therefore, considering the above issues, a novel multiport hybrid dc circuit breaker (MHCB) is proposed in this article. The MHCB mainly has three advantages: the reduced implementation cost by sharing the expensive main breaker among multiple lines, the reduced fault isolation time by bypassing the current limiting inductor during energy dissipation, and the ability to reclose softly. Extensive simulations and experiments verify the effectiveness of the device. In addition, the comparison of the new device and existed solutions is presented. [ABSTRACT FROM AUTHOR]

Two key challenges in meshed multi-terminal dc (MTdc) grids are line power flow management and fault current interruption, which can be solved by current flow controllers (CFCs) and hybrid dc circuit breakers (HCBs), respectively. However, the power losses and the implementation costs of CFCs and HCBs are relatively high. In order to overcome these drawbacks, a combined HCB (CHCB) is proposed in this article by fully utilizing the core ideas of the interline dual H-bridge CFC and the HCB. The proposed device can substitute multiple HCBs at a dc bus with greatly reduced cost. In addition to the fault current interruption capability, the current flows in the adjacent lines can be controlled by the embedded multi-line CFC in the CHCB expanded from the existing interline dual H-bridge CFC. The system-level behavior of the proposed CHCB is similar to the separate solution of the typical HCB and the multi-line CFC. Extensive simulations and experiments verify the effectiveness of the proposed device. Besides, a comparison of the proposed CHCB and the separate solution is presented. [ABSTRACT FROM AUTHOR]