Design of an IGBT-series-based Solid-State Circuit Breaker for Battery Energy Storage System Terminal in Solid-State Transformer

In medium-voltage direct-current (MVDC) distribution grid, the solid-state transformer (SST) with battery energy storage system (BESS) can be used for energy exchange, voltage matching and port power decoupling, etc. However, when dc grid-side short-circuit fault occurs, the energy storage terminal of such transformer should have the ability to prevent from large overcurrent which may violate the safe operation of the system. This paper proposes a cost-efficient solid-state circuit breaker (SSCB) using series-connected IGBTs configured at the terminal of BESS for fault-isolation purpose. A multi-pulse fault-detection method (MPFD) for the SSCB is also proposed, which can not only realize fault-isolation, but also alleviate the thermal dissipation of IGBTs and achieve the voltage-balancing of series-connected switches cycle by cycle. Such an overcurrent protection can contribute to the reliability improvement of the SST system.