Multi-Port Hybrid DC Circuit Breaker Based on Bridge Commutation Branch

Flexible dc grids have become an important means to support large-scale new energy integration utilization due to their advantages of flexible power control and high efficiency. Flexible dc grids generally consist of multiple converter stations and dc lines. Therefore, there are multiple line intersection points, and dc circuit breakers (DCCBs) need to be installed at the intersection to isolate faults. Multiport hybrid DCCBs (MPHCBs) based on topology optimization can greatly reduce the cost by replacing multiple two-port DCCBs with one multiport DCCB at the intersection. However, currently researched multiport DCCBs still have a high cost and large volume while lacking engineering verification. This letter proposes a hybrid multiport DCCB based on a bridge commutation branch that greatly reduces the number of power electronic devices used and the cost and volume of the DCCB. First, the topology and control method of the proposed MPHCB are studied, and its cost and reliability are analyzed. Then, the breaking test of the proposed MPHCB based on the bridge commutation branch is carried out at a 15 kV voltage level. The results show that the proposed MPHCB can interrupt a 15 kA current in 3 ms, which verifies the feasibility of the scheme.