Investigations on Droop Control for Stable Transitions Between Islanded and Grid Operations in Microgrids

This paper investigates parallel inverter architectures in grid-connected PV systems, focusing on utilizing a droop control strategy (P-ω and Q-E) to enhance active and reactive power sharing. The objective is to ensure stable voltage and frequency in isolated and grid-connected modes in microgrid configurations, which include two PV-connected inverter units of different ratings, a 3-φ load, and a grid. This paper is particularly relevant for implementation in remote villages where solar-tied parallel inverter systems are utilized. The proposed control strategy is also extended to the parallel-connected inverter units. According to this method, no communication channel needs to be established between inverter units, and it offers a prominent solution for areas with multiple PV sources. Along with MPPT, the proposed system optimizes power-sharing. Regulation of voltage and frequency during varying loads in both islanded. Grid-tie modes further justify this control methodology as an engineering solution to improve the performance of parallel-connected solar PV systems. Simulated results validate the robustness of the control methodologies presented here.