A New Method of Coordinating ZCBs and Fuses for a Reliable Short-Circuit Protection in DC Power Networks

With the increasing installations of solar energy, electric vehicles, and other dc-nature power devices in modern systems, short-circuit protection high-power dc circuits is critical HVDC transmission MVDC distribution networks. As a promising protective device, Z-source Circuit Breaker (ZCB) has some unique good features over approaches. But, under circumstance slow-developing faults, ZCB might be “blind” fails to protect circuits. In this paper, new method coordinating fuse developed specify properly compensate ZCB’s functionality thus introduce complete “thermal-magnetic” function hybrid ZCB-fuse circuit breaker. By analyzing current-limiting their interactions, two constraints are identified for proposed coordination relevant thresholds melting energy formulated. A five-step verified by simulation tests with various fault current levels changing time. It proven that, following method, coordinates well as backup designated peak tolerable current. This research work helps increase reliability ZCBs systems.