Design of Bidirectional Z-source Solid-state DC Circuit Breaker with Low Loss

With the continuous development of DC transmission and distribution technology, the problem of DC fault protection is becoming more prominent. As an important device for fault protection, the circuit breaker is gradually developing in the direction of low loss and fast operation. The Z-source solid-state DC circuit breaker has the characteristics of simple structure, rapid response, and arc-free disconnection, which provides a new solution to DC protection. Therefore, this paper proposes a novel bidirectional Z-source solid-state DC circuit breaker. Based on the analysis of its working principle, its design method is given, and the protection characteristics of the existing typical Z-source DC circuit breakers are compared. The novel circuit breaker uses capacitors to replace the reverse blocking effect of diodes in the traditional structure, reduces on-state loss of the circuit breaker, and realizes bidirectional energy flow through reverse-parallel thyristors, without additional detection and control circuits. And the rapid and automatic response to short-circuit faults can be realized through the design of impedance network parameters. Finally, the validity of the designed solid-state DC circuit breaker is verified by simulations and principle prototype experiments. © 2022 Automation of Electric Power Systems Press.