Dc micro grid protection with the z-source breaker

Abstract

Many components of a modern micro grid operate using a dc interface including solar panels, fuel cells, and battery energy storage. For this reason, a dc micro grid has been suggested and utilized in some power systems. With the absence of a zero-crossing in the current waveform, the dc breaker faces a unique challenge in that there is no natural method of extinguishing an arc that occurs during breaker operation. This is handled in practice by using over-sized ac breakers, using a solid-state breaker, or using a hybrid solid-state/mechanical breaker. A recently introduced z-source breaker is a unique form of the solid-state breaker that automatically reacts in real-time to system faults; not requiring the typical fault sensing and detection. It has the ability to clear the fault within microseconds. Furthermore, the source will not experience the fault current. In this paper, the theory behind the z-source breaker is reviewed and the breaker is studied in the context of several micro grid topological arrangements using non-real-time and real-time simulation.