Robust hybrid control of parallel inverters for accurate power-sharing in microgrid

There are some challenges in control of parallel inverters in high-voltage microgrids such as voltage and frequency deviations, presence of communication links, low reliability, and inaccurate power sharing. This paper proposes a hybrid control method using the impedance-power droop and conventional droop method to cover the problems of both methods as much as possible. In the proposed method, the impedance-power droop acts as the main controller and the conventional droop method is employed as auxiliary controller during startup and transient states. The notable advantages of the proposed method are low virtual impedances, no need for recognition of system parameters, and simple and low calculations. Moreover, the voltage deviation in the steady state is minimized and the frequency deviation is completely eliminated. Finally, the performance of the control method is validated by simulation results. The hybrid method is compared with the both methods individually that shows the superiority of the proposed method.