Active Voltage Regulation Transformer for AC Microgrids

This paper presents a novel active voltage regulation transformer (AVRT), to guarantee on-load voltage regulation of AC microgrids, even when supplying unbalanced loads. The proposed AVRT includes a 4-leg AC/AC matrix converter and a series transformer to allow the voltage regulation in the low voltage (LV) AC microgrid. Using the space vector representation, a sliding mode control approach is proposed for the 4-leg matrix converter, and the voltage in the microgrid is then controlled using a linear control approach. Obtained results show that the proposed system regulates the voltage in the LV microgrid even when the loads are unbalanced. Additionally, it allows regulation of the voltage in the microgrid in case of a voltage sag or an overvoltage in the medium voltage (MV) side.