Review on design and control of solid state transformer based microgrids

Solid state transformer (SST) is a high frequency switched power electronic based transformer with high controllability that enables flexible connectivity between existing medium voltage power distribution network, low voltage AC residential system and envisioned DC residential system. The SST is not a direct replacement of a conventional low frequency transformer, but a multi-purpose device that offers improved functionalities. The demanded requirements of the future power systems such as integration of distributed generation, DC loads and storage have enabled the microgrid technology to evolve. This paper is focused on the SST as an intermediary tool for microgrids. An overview of existing and possible SST based microgrid designs and control architectures, their advantages, disadvantages and the identified selection criteria are presented. With a special focus on existing experimental setups, the paper is concluded highlighting the possible areas of research that would enhance the integration of the SSTs into microgrids in the future.