An integrated multi-port hybrid DC circuit breaker for VSC-based DC grids

DC circuit breakers are of great significance for the reliable and flexible operation of VSC-based DC grids. The hybrid DC circuit breaker (HDCB) combines the advantages of low on-state loss of the mechanical DC circuit breaker and fast breaking speed of the solid-state DC circuit breaker, showing excellent application prospects. However, the cluster of two or more HDCBs connected to the same DC bus could significantly increase the total project investment. At present, the solution based on multiport HDCB (M-HDCB) has been proposed to practically reduce the construction cost, but the power transmission among adjacent healthy DC lines will also be interrupted after the isolation of DC bus fault, which is still a challenging problem. Therefore, in order to solve this problem, a novel integrated multiport HDCB (IM-HDCB) is proposed in this paper. In addition to the shared transfer and energy dissipation branches, the key auxiliary units composed of diode-stacks and thyristor-stacks are also integrated into the IM-HDCB to enhance the overall performance. Compared with existing solutions, it is shown that the proposed IM-HDCB has more excellent performance. Finally, the capabilities of the proposed novel IM-HDCB are validated by simulations in PSCAD/EMTDC.