Operation of Meshed Hybrid Microgrid during Adverse Grid Conditions with Storage Integrated Smart Transformer

Abstract

Microgrid faces various challenges such as reverse power flow, peak power demand, voltage limit violations, etc., due to significant installations of renewable energy sources (RESs) and electric vehicles (EVs). For continuous and effective operation of such a system, enhanced and complex control methodologies are needed. Smart transformer (ST) has emerged as a promising solution for overcoming such challenging issues. This paper proposes the operation of battery energy storage system (BESS) integrated ST in a meshed hybrid microgrid. Instead of connecting through ac interconnections with normally open (NO) circuit breakers (CBs), the same line is connected through the medium voltage (MV) dc links of ST. This introduces several paths for controlled power flow in the system. As compared to ac interconnections, this configuration improves the performance of the overall system during various adverse operating conditions such as reverse power flow, peak power demand, and voltage sag. Moreover, the MVDC line voltage is controlled by one ST, resulting in reduced control complexity of other power converters. Detailed simulation and experimental results are provided to show the merits of the proposed system.