A multi-port DC circuit breaker with fault-current limiting capability

The DC circuit breaker (DCCB) is the key equipment to realize the fast interruption of fault currents for VSC-based DC grids. At present, the hybrid DCCB characterized by low loss and fast breaking is widely considered as one of the important development directions in the future. However, the hybrid DCCB requires a large number of cascaded power electronic modules in the transfer branch to withstand the electrical stress in the breaking process, which not only directly leads to high development cost, but also seriously restricts its large-scale applications. In order to adapt to the protection requirements proposed by VSC-based DC grids and reduce the construction cost, based on the study of operation principles of fault-current limiters and the traditional two-port hybrid DCCBs, a multi-port DCCB with the fault current limitation capability is proposed in this paper, which not only improves the fault current limitation performance, but also reduces the energy dissipation stress of the metal oxide varistors, and moreover ensures the continuous and reliable operation of VSC-based DC grids to the greatest extent. Finally, the performance of the pro-posed multi-port DCCB with fault-current limiting capability is verified in PSCAD/EMTDC, which shows that the proposed multi-port DCCB has significant effectiveness and adaptability.