Application of multi-port solid state transformers for microgrid-based distribution systems

Recent developments in the design of power electronic elements with higher voltage and power rating and medium/high frequency enable the use of solid state transformer at different voltage levels for microgrid design. In this study, the concept of a Multi-Port Solid State Transformer (MPSST) for distribution network application is introduced to achieve the goal of creating galvanic isolation between different nodes connected to the converter and between upper and lower zones in a zonal microgrid. MPSST enables compact, integrated and galvanically isolated multi-port node for the microgrid elements and at the same time reduces the number and size of converters. This article proposes a new architecture for the distribution system with dispersed Distributed Generation (DG) resources in all voltage zones of the network using MPSST as the main component in the system. The developed concept interconnects different voltage types and levels using a single compact converter with a centralized control logic. By controlling the phase shift between ports of the converter, the power flow through the legs can be controlled. Also the voltage of different legs is actively regulated.