Improved MVDC Breaker Operation by Active Fault Current Sharing (FCS) of Existing Power Converters for Shipboard Applications

In this article, an active fault current sharing (FCS) strategy is proposed to improve the dc circuit breaker (CB) operation in a breaker-based medium-voltage dc (MVdc) system. The peak turn-off current of CBs can be decreased by controlling the existing converters located in parallel with activated CBs to share the fault current. This reduction effect can be amplified from the systematic perspective since one single converter with the proposed FCS can benefit different CBs in various fault scenarios. The short-circuit fault scenarios of a shipboard breaker-based MVdc system are analyzed and the corresponding fault equivalent circuits, including power converters adjacent to CBs, are developed. The device stress of voltage-fed (VF) and current-fed (CF) converters applying the proposed active FCS strategies during short-circuit faults is derived and compared with those of passively shutdown counterparts. Finally, a downscaled experimental test bed was built to emulate a 6-kV/6-MW MVdc system fault scenarios. The experimental results are provided to verify the proposed FCS.

Automated summary

This article proposes an active fault current sharing strategy to improve the operation of circuit breakers in a medium-voltage DC system. By sharing fault current, the peak turn-off current of circuit breakers can be reduced, benefiting multiple circuit breakers in different fault scenarios. Experimental results from a downscaled test bed validate the effectiveness of the proposed FCS strategy.