An Impedance-Power Droop Method for Accurate Power Sharing in Islanded Resistive Microgrids

摘要

In this paper, a novel and simple control strategy is proposed for parallel inverters in islanded resistive low voltage (LV) microgrids. In the proposed algorithm, first, the effect of inherent inverter impedance is removed by a proper feedforward term. By eliminating inherent impedances, power sharing is affected only by microgrid line impedances. Then, the new impedance-power droop is proposed based on the virtual impedance. The proposed control method can accurately share the load power, without recognition of microgrid parameters and high-bandwidth communication links. The parameters of the proposed controller are designed systematically based on the nominal power of the inverters and the approximated impedance of microgrid lines. Also, the stability of the whole closed-loop system, including the feedforward and impedance-power droop, is evaluated. Finally, simulation and experimental results confirm the feasibility of the proposed control scheme and its application, even in the presence of local loads and more than two inverters.