Research on Breaking Function for Two Bidirectional Γ-Source DC Solid-State Circuit Breakers

This article proposed two bidirectional Gamma-source dc circuit breakers (Bi-Gamma DCCB1 and Bi-Gamma DCCB2) only using diodes and mechanical switches to construct bidirectional topology without introducing passive components, leading to owning a simpler and smaller structure in terms of bidirectional dc circuit breakers. Both of these proposed circuit breakers have the advantages of common ground between source and load, accurately and quickly isolating bidirectional faults. Meanwhile, the operation modes including steady-state, fault isolation, resonance, and inductance discharge of two bidirectional Gamma-source circuit breaker topologies have been analyzed, the model of the bidirectional Gamma-source circuit breaker at different stages has been established, and the turn-off time of thyristor, the minimum detectable fault admittance rise rate, and the device parameters design of circuit breaker are calculated in detail. Then, this article provides a multidimensional and systematic comparison and summary of the circuit breakers studied by previous scholars. Finally, the experimental results have verified that the two proposed bidirectional dc circuit breakers can achieve effective bidirectional autonomous breaking and bidirectional manual breaking performance in short-circuit faults, and have the ability to identify load step changes.