Performance of 3-phase 4-wire solid state transformer under imbalanced loads

The modern distribution grid has seen a substantial change in load profile over recent decades, with a growing proliferation of imbalanced loads. This presents a major challenge for power quality on the distribution grid leading to a possible re-evaluation of grid topologies. The Solid Sate Transformer (SST) is a potential enabling technology to control and regulate system operation under these imbalanced conditions. This paper investigates the operation of a 3-stage SST design (Rectifier-Dual Active Bridge — Inverter) under imbalanced load conditions. The performance of the SST in a 3-phase, 3 wire system and in a 3 phase, 4 wire system is studied using Matlab based simulations. It is shown that the proposed SST can ensure distribution level feeder voltage balance in the face of significant voltage imbalance.