Performance analysis of RCD and MOV snubber circuits in low-voltage DC microgrid system

Abstract

In order to protect solid-state circuit breaker (SSCB) from transient impacts under short circuit fault, an effective and economical snubber design is quite important. Traditional RCD snubbers are widely used because of their good voltage-clamping ability and short fault clearing time. Meanwhile, metal oxide varistor (MOV) also emerges as a suitable solution due to its non-linear U-I characteristic and simplicity. To optimize snubber design, it is imperative to analyze and compare the performance of these two snubber candidates. Therefore, a set of measurements is selected to focus on the performance analysis of RCD snubber and MOV, which contains five indicators: peak SSCB voltage, peak bus current, fault clearing time, snubber reliability and cost. A ±200 V Low-voltage DC (LVDC) system experiment is conducted for comparison. The results show that improved RCD snubber, Discharge-Suppressing Type I has smaller overvoltage but its cost is much higher than that of MOV. MOV stands out for shorter fault clearing time, however, its transient fluctuation is larger than that of RCD.