Modified Controller for Smooth Transition of Grid-Connected and Standalone Modes in AC Microgrid

Microgrids have significant potential in delivering high power quality and an uninterrupted power supply, enhancing reliability and stability for all consumers. Intelligent control techniques are essential for the reliable and stable operation of microgrids. These systems can function in two modes: utility grid-connected and standalone. In the utility grid-connected mode, distributed generators (DGs) typically operate under grid-following control, while in standalone mode, at least one DG must use grid-forming strategies. Microgrids may encounter voltage and current fluctuations during unintentional standalone events. This paper introduces a novel approach to seamlessly synchronize utility grid-connected and standalone modes while effectively mitigating disturbances. The strategy involves implementing a Modified Voltage Controller (MVC) with capacitor current feedback (CCF) and load current feed-forward (LCFF) to enhance system dynamics, broaden the controller’s bandwidth, and suppress voltage, current, and frequency fluctuations. This ensures a smooth transition between utility grid-connected and standalone modes in AC microgrids, validated through simulation results in the paper.