A Multiport DC Breaker With Integrated Energy Dissipation Capability for Offshore MTDC Systems

DC circuit breakers (DCCBs) and dc choppers are reliable solutions for flexible multiterminal dc (MTdc) transmission systems under offshore–onshore integration, as they ensure uninterrupted operation during ac/dc short-circuit faults. However, their high costs challenge their widespread applicability. In this article, a multiport hybrid DCCB with integrated energy dissipation capability (MP-IEDC-HDCCB), achieving high performance and lower cost, is proposed. The principle of handling dc faults is given, and the performance is theoretically analyzed, which is verified in a four-terminal MTDC simulation system. Based on the theoretical analysis, the configuration of components is compared with typical schemes. Besides, the feasibility of the proposed device is validated on a scaled-down hardware experimental platform. It can be seen that the proposed device can clear dc fault current within 5 ms and stabilize dc voltage within 10%. Compared to two-port DCCB with dc chopper, this device offers a cost reduction of 58.8% at least. The theoretical analysis, simulation verification, and experimentation showcase the potential for enhancing the cost-effectiveness of MTDC systems.