Cascaded commutation circuit for a hybrid DC breaker with dynamic control on fault current and DC breaker voltage

Abstract

This study proposed a cascaded commutation circuit based on current commutation approach for low- to medium-voltage DC fault current interruption, without snubber circuits, which slows the fault current di/dt prior to current-zero and the rate of rise of the transient recovery voltage dv/dt across the mechanical breaker contacts after current-zero. The proposed dynamic control of the fault current di/dt and circuit breaker voltage dVVCB/dt increase the fault current interruption capability at the first and second current-zeros. Detailed mathematical equations are presented to evaluate the operational waveform profile and the validity of the cascaded commutation principle is confirmed by simulation and experimental results at 600 Vdc, 110 and 330 A.