A High-Performance and Economical Multiport Hybrid Direct Current Circuit Breaker

Hybrid DC circuit breaker (HCB) is an effective device for interrupting DC fault currents in DC grids. Conventional two-port HCB requires too many IGBTs in series in its main breaker, resulting in considerable costs. Recently proposed multi-port hybrid DC circuit breakers (multi-port HCBs, and the number of ports is greater than or equal to 2) interrupt fault currents on multiple lines using only one shared main breaker, significantly reducing the implementation costs but losing some fault handling capabilities. To overcome these obstacles, we propose a novel high-performance economical multi-port hybrid DC circuit breaker (MP-HCB) in this paper. The topology and its control method are proposed. Due to the designed ring-connection structure, the proposed MP-HCB can avoid DC bus fault, and thus is more reliable. The electrical stresses of the breaker are theoretically analyzed, and the parameters are determined to make the MP-HCB capable of multiple-line faults. Compared with the typical two-port HCB and the existing multi-port HCBs, the proposed MP-HCB can achieve full fault current interruption capability with lower costs. To protect a DC node connecting with three lines, the cost of the semiconductors of the proposed MP-HCB is only 1/3 of the typical two-port HCB and 1/2 of the existing multi-port HCB. Finally, the performances of the proposed MP-HCB are verified via a four-terminal HVDC system in PSCAD/EMTDC.