PERFORMANCE INVESTIGATION OF SOLID STATE TRANSFORMER (SST) BASED DC MICROGRID SYSTEM

Abstract

The motivation behind development of SST is to provide a robust, lightweight and controllable solution for power transfer between two different AC voltage levels. Significant reduction in weight is achieved by replacing conventional transformer with a high-frequency transformer isolated power electronic converters. In the past few decades, deregulation of power generation is being considered as a viable option to meet the increasing power demands. The deregulation policy has resulted in increased penetration of distributed energy resources (DER) in the distribution system, which is now causing power quality issues. The harmonics introduced in power system by DER’s are posing challenges for transformer design. The resulting active power electronic transformer (APET) complies with all requirements of the smart grid concept. This report presents an overview of all the three major stages of the Solid State Transformer (SST) i.e the AC to DC rectifier stage, DC to DC Dual Active Bridge & DC to AC Inverter stage. The simulations of all the respective stages have been performed and satisfactory results have been obtained. A comparative analysis of various control strategies of AC to DC boost rectifier stage has been made in detail and from the results obtained optimum strategy has been suggested. A prototype of single phase AC-DC active boost rectifier has been developed in the laboratory environment to validate the simulation results, which has been reported at the end