DESIGN AND OPERATION OF A SOLID-STATE TRANSFORMER FOR INTEGRATION OF RENEWABLE ENERGY SYSTEMS

Abstract

Renewable energy-based grid integrations in distribution systems cause changes in the energy structure of the grid such as load flow, short circuit and protection coordination. Today, conventional transformers are insufficient in meeting the needs of loads with different profiles and in connection with renewable energy sources such as solar and wind to the grid. Additional mechanisms are needed to overcome power quality problems, especially voltage rise and fall, fraying, or harmonics. With the advances in semiconductor technology, power electronics has emerged as a promising solution to dealing with the problems of complex power systems. Solid-state transformer (SST) is a novel technology that can affect developments in many fields such as renewable energy systems, smart grids, distribution tail systems for flexible power conversion between medium voltage distribution and low-voltage customer side. Compared to the conventional transformers, SSTs provide reactive power compensation, simple connection of renewable energy sources and battery systems, power factor correction, galvanic isolation, smart protection, harmonic control and frequency conversion. As a result, the integration of renewable energy plants to the electrical grid creates big challenges in terms of harmonics, power flow control, power factor correction, isolation and smart protection. Thus, SSTs will play a significant role in future grid topologies. In this study, modeling and analysis of a solid-state transformer for a grid-connected solar PV plant are carried out with MATLAB/Simulink. The power analyses of the proposed system are examined thanks to the simulation study. This analysis would be a significant contribution to the development and implementation of renewable energy-based applications of the SSTs.