500kVA Hybrid Solid State Transformer (HSST): Modelling and Control

This paper presents a full order average model of a Hybrid Solid State Transformer (HSST) and a controller design to regulate the HSST output voltage. The developed 500kVA HSST comprises of a higher-power line frequency transformer (LFT) and a lower power Solid State Transformer (SST). The SST is based on a soft-switched single stage dual-active bridge (DAB) AC/AC topology. The model and the controller have been verified through simulation studies. The HSST has been tested in several scenarios to validate the controller experimentally.