An Improved SSCB Combining Fault Interruption and Fault Location Functions for DC Line Short-Circuit Fault Protection

At the occurrence of a permanent fault in a DC microgrid, apart from isolating the faulty section using a solid-state circuit breaker, the protection system should also have the fault position located so that repair crew can be sent to clear the fault and restore the isolated section. Available fault location methods are either influenced by network topology or need to add costly equipment. Located immediately next to the faulty line, the solid-state circuit breaker has the advantage of position required for injecting and detecting fault location signals, and it is isolated from the rest of the system by disconnector after fault interruption. Therefore, using the solid-state circuit breaker for fault location has a potential research value. However, it is rarely discussed in previous literatures. In this paper, an improved topology of the solid-state circuit breaker is proposed, which is able to inject signals into the isolated faulty line to determine fault position. By reusing components, the improved topology can achieve function expansion without much increasing the size and cost for fault protection, obtaining an accurate result uninfluenced by the network topology. Simulations and experiments are conducted in a 200 V/DC system to verify the effectiveness of the design.