8th International Conference on Advanced Power System Automation and Protection (APAP2019)

893 / 2019-04-30 14:56:04

A Novel Mechanical DC Circuit Breaker Based on Pre-charged Capacitor

DC circuit breaker,Current interruption,Active current injection

Mechanical DC circuit breakers （MDCBs） have attracted extensive attention because of their low construction cost and low conduction losses. Traditional MDCBs require AC grids to pre-charge capacitors, thus, their application is limited when the active AC grid is non-available. In this paper, a novel MDCB is proposed, which pre-charges capacitors using DC system voltage. The capacitors can be pre-charged to a desired value by adjusting the ratio of two capacitances. During interruptions, the capacitor discharge current creates a current zero in the mechanical breaker and commutates the fault current into the capacitor. With the increase of capacitor voltage, the fault current commutates to the arrester and gradually decreases to zero. The performance of the novel MDCB is verified using PSCAD/EMTDC simulations. Because the pre-charging AC grid is avoided, the novel MDCB has lower cost and is more suitable for DC grids compared to traditional MDCBs.