A multi‐port hybrid circuit breaker integrated with power flow control ability

Abstract

Power flow controllers and DC circuit breakers are compulsory components in a multi-terminal DC grid with overhead lines. They are both composed of similar power electronic devices and thus can be reasonably combined together to realize cost savings. This paper proposes a multi-port circuit breaker integrated with a multi-port power flow controller (M-PFCHCB). The topology structure, operation principles, control strategy and parameter configuration are illustrated in detail. The main breakers are composed of unidirectional power electronic switches, and the selection branch is based on two diode strings, which can significantly save the investment of the breaker. The proposed M-PFCHCB is able to deal with the fault isolation and the ultra-fast disconnector failure with high performance. Besides, the power flow of multiple lines can be simultaneously regulated by the M-PFCHCB without any external power supply. The internal power balance is achieved by controlling the AC circulating current inside the M-PFCHCB. The simulations conducted on PSCAD in a five-terminal DC grid with eight DC lines verify the feasibility of the proposed M-PFCHCB. The technical and economic analysis performed proves that the proposed M-PFCHCB can achieve the comprehensive functions of fault isolation and power flow control with low construction cost.