Semicentralized Power Sharing Scheme for Islanded Parallel-Connected Inverters

This paper presents a new control scheme that permits flexible power sharing between parallel inverters connected to microgrid operating in an island mode. The presented scheme processes the information of active and reactive output powers from all inverters in a central controller that calculates the set points for each inverter, based on the desired ratios of their output powers. These necessitate adjustment of the inverters’ terminal voltages (phase and magnitude) relative to the voltage at the common AC bus. The proposed power-sharing scheme uses a robust low bandwidth-based sharing communication to achieve precision and fast dynamic response, minimum circulating current between parallel inverters, and adapting to changes in line impedance, even under information transfer delays. The presented power-sharing scheme has been validated using MATLAB/Simulink simulation and experimental results obtained from a prototype of three three-phase parallel inverters connected to a number of loads. The results emphasize the superiority of the proposed topology performance under different loads (25% to 100%), line impedances, grid conditions, and communication delay.