A novel control strategy of an islanded microgrid based on virtual flux droop control and direct flux fuzzy control

This paper proposes a novel control strategy of an islanded microgrid based on virtual flux droop (VFD) control. In the conventional VFD method, the direct flux control (DFC) technique is used to generate the switching signals using the hysteresis regulators and a switching look-up table. Therefore, the voltage and the current ripples are inevitable. Moreover, as a single switching vector is applied in each control period and none of the switching vectors can produce the desired voltage, the desired dynamic performance is not achieved. Here, a novel direct flux fuzzy control (DFFC) technique is proposed to choose the best switching vector based on fuzzy logic. Furthermore, only a fraction of the control period is allocated to an appropriate active switching vector which is selected by the DFFC technique whereas the rest of the time is allocated to a null vector. The duty cycle of the selected active switching vector is optimized using a simple and robust mechanism. In order to evaluate the performance of the proposed method, an islanded microgrid and the proposed control strategy is simulated in Matlab/Simulink software. The results prove that the dynamic performance response is improved and the demanded load power is proportionately shared between the sources, while the voltage and current ripples are significantly reduced.