Modular solid state transformer for low medium voltage applications

Abstract

The electric service providers are under constant pressure to afford high quality uninterruptible service to modern day consumers. The renewable energy infiltration into the grid following the ever-rising demand for power necessitates new infrastructure to assimilate storage as well as to allow for better control and more consistent operation of the distribution system. While system expansion can be done to match the mounting need for load capacity,the issues related to source voltage variation, load oscillations, voltage range limitation and other power quality disturbances can be managed only with smart solutions. One such solution is the Smart Transformer based on solid state approach. The Solid State Transformer (SST) is a modernized form of Conventional Distribution Transformer (CDT) with control flexibility and multifunctional capabilities. This thesis presents a single phase minimal footprint three-stage Modular Solid State Transformer (MSST) suitable for low/medium voltage applications. The MSST is an assembly of solid state converters with suitable control circuitry and a high/medium frequency transformer (HFT/MFT). The right pick of the converter topologies among the available choice is the key to accomplish superior functioning of the MSST. In this context, various converter topologies for the ac/dc, dc/dc and dc/ac stages of MSST are explored and the appropriate ones with least device count and simple control without compromising on the performance and efficiency are chosen for implementation. newline newline newline