Coordinated Control of Voltage Unbalance Compensation in Islanded Microgrid Based on Particle Swarm Optimization Algorithm

The system voltage of microgrid in the islanded operation mode is fully supported by the coordinated operation of all microgrid inverters in the network. Thus, the supply voltage quality of the microgrid is highly dependent on the control performance of microgrid inverters. Due to the existence of a large number of single-phase loads, the system load is usually unbalanced, which causes system voltage unbalance. In solve this problem, aiming at controlling the unbalance degrees of voltages both at the inverter port and the point of common coupling (PCC), this paper proposes a compensation algorithm for negative voltage based on the particle swarm optimization (PSO) algorithm, which starts from analysis on unbalance mechanism. The unbalance degrees of voltages at inverter port and PCC are taken as the constraint conditions to establish the objective function. At the same time, the problem of circulating current between inverters is also taken into account. Consequently, the circulating current among microgrid inverters is suppressed while the voltage unbalance degree is controlled. Finally, based on MATLAB and a power electronic real-time simulation platform, the system simulation model and the semi-physical real-time simulation model are built. The simulation and experimental results verify the correctness and effectiveness of the proposed method. © 2020 Automation of Electric Power Systems Press.