A New Reactive-Power Sharing Scheme for Two Inverter-Based Distributed Generations with Unequal Line Impedances in Islanded Microgrids

This paper proposes a new reactive-power sharing scheme to reduce the circulating current when two inverter-based distributed generations (DGs) operate in parallel through unequal line impedances in an islanded microgrid. If the terminal voltages of the two DGs are not equal due to the unequal line impedances, a circulating current due to reactive-power unbalance occurs, which increases system loss. The proposed droop control compensates the terminal voltage difference to reduce the circulating current by considering a feed-forward path of the line voltage drop. The feasibility of the proposed droop control was first verified through computer simulations, and then experiments with a hardware set-up in the lab. The experimental results were compared with the simulation results to confirm the feasibility of the proposed droop control.