Fault-Aware-Soft-Restart method for shipboard MVAC power system using inverter coupled energy storage system

Abstract

We show that an inverter coupled energy storage system can be used to provide a soft-restart for the zonal loads by first operating in a “protected ride-through” mode, then pre-energizing the loads, and finally transfer the loads bumplessly to the main generator. This method decreases by over 50% the inrush currents associated with restarting the loads. The inverter is controlled to achieve a voltage and phase matched condition with the main generator before the load transfer takes place so as to minimize voltage or current oscillations associated with reclosure. This process, termed as “Fault-Aware-Soft-Restarting” can eliminate the problems of 1) Unwanted fault-feeding 2) Motor starting inrush currents that causes voltage dips and motor stalling in nearby load zones and, 3) Breaker reclosing transients that may damage line equipment or cause secondary trips.