Regulation of parallel converters based AC microgrid considering non-ideal grid conditions

Abstract

This study proposes an alternating current microgrid that integrates renewable energy sources to enhance energy sustainability. In this system, wind and solar power are initially converted to DC using DC–DC converters; subsequently, they are integrated into a common AC bus through parallel voltage source converters. The goal is to provide uninterrupted power to local loads while addressing power quality issues and efficiently managing power flow within the system. The main contribution of this study is the development of a unified power flow strategy that ensures reliable power delivery by considering peak and off-peak electricity pricing, as well as the battery state of charge for optimised grid and storage utilisation. Moreover, when the power electronics circuitry is integrated with renewable energy sources, the grid encounters power quality issues at the point of common coupling. Therefore, to mitigate power quality issues at the point of common coupling, particularly with power electronics integration, a frequency-locked loop based on an amplitude integrator, coupled with a harmonic decoupling network, is used to extract the fundamental components of the grid voltage and reduce harmonic distortion. The proposed topology and control strategies are validated through laboratory testing using a hardware prototype, with the test results demonstrating their effectiveness.