An improved controller for reactive power sharing in islanded microgrid

The control to stabilize the frequency and voltage is the main goal of controlling the islanded microgrid. The microgrid can include different inverters, which are connected in parallel to each other by lines that have different impedances. The loads in the microgrid include local and public loads. With the different line impedances and local loads, it has made the voltage and current controller-type PI (proportional integral) or PID (proportional integral derivative) unable to guarantee the stability for the microgrid, and also, the power sharing between inverters is not made accurate. In this study, an improved power sharing controller is proposed by adjusting the droop voltage slope, in order to increase the accuracy of power sharing, while the microgrid has local loads and the line impedances have significant differences for inverters connected to a microgrid. This controller is combined with a sliding mode control to improve accuracy in power sharing and improve the quality of the voltage supplied to the loads. The control model has been simulated and experimental with two inverters connected in parallel. The simulation and experimental results demonstrate the effectiveness of the proposed control method.