An improved bidirectional T-source circuit breaker for MVDC

As the developed version of solid-state circuit breaker, Z-source circuit breakers are providing an attractive research interest as a protection system in DC. Based on the typical Z-source circuit breaker, many topologies have been proposed in recent studies to reduce the breaker size or to demonstrate the breaker performance in different voltage conditions. In this paper, an improved T-source breaker is proposed for medium voltage DC to provide the bidirectional operation which has also become the general requirement for the modern power system. The topology proposed in the paper uses the arrangement of a capacitor, a two-winding transformer, and a set of four diodes to facilitate the bidirectional operation. First, the circuit modeling is formed for the proper size estimation of the breaker components, and then, other properties of the breaker including minimum detectable fault, fault ramp rate, and filter characteristics of the breaker are also analyzed. By the analysis of several overload conditions and short-circuit conditions studied through the simulation for medium voltage level, and experimental prototype in low voltage level, the performance of proposed breaker in different condition is verified to be efficient and satisfactory.