Efficiency Improvement of Parallel Source Inverters in Islanded AC Microgrid

The limited capacity of a single inverter has led to the implementation of parallel inverters for interconnecting renewable energy generation systems. Droop control is commonly used for operating parallel inverters; however, conventional droop control has a low conversion efficiency under heavy loads. Therefore, this paper designed an efficient control strategy to enhance the conversion efficiency of parallel inverters. The employed method incorporates an internal current and voltage control loop based on a synchronous reference frame, along with conventional PI controllers. Additionally, Particle Swarm Optimization (PSO) is utilized to determine the optimal conversion efficiency of the parallel inverters. In this approach, the distributed generation (DG) unit adjusts its control mode to modify system voltage and frequency in response to dynamic load conditions. Efficiency improvements were observed in the range of 0.19% to 0.41% across various initial power distribution ratios, highlighting the efficacy of optimized droop parameters in maintaining robust and efficient power systems. Simulation results using MATLAB/SIMULINK demonstrate that the proposed control system improves system efficiency