Topology of a thyristor based bidirectional DC circuit breaker and its control strategy

HVDC circuit breaker is an important protection device for DC power grid, also a key equipment to promote the development of DC grid. When the fault occurs, it can effectively cut off the fault current and prevent the expansion of the failure. In this paper, we proposed a thyristor based hybrid HVDC circuit breaker scheme based on the existing main hybrid HVDC circuit breakers, which has shown advantage in high switching speed, low cost and easy implementation. The theory of the proposed scheme is firstly introduced, together with calculating various stages of the equivalent circuit by the mathematical analysis. Meanwhile, an electric current pretransfer strategy is also provided for different running states. The effectiveness of the proposed control strategy and the feasibility of the topological structure of the proposed HVDC circuit breaker are eventually proven through a Matlab simulation research.