A novel real-time voltage and frequency compensation strategy for photovoltaic-based microgrid

Weather-dependent photovoltaic (PV) system power variation may become frequent and rapid, which could be regarded as perturbation for the microgrid (MG). This perturbation would lead to voltage and frequency fluctuations and dramatically degrade the MG performances. Conventional secondary control strategy could restore the voltage and frequency after a certain time delay, but it cannot satisfy the speed demands when frequent and rapid perturbations appear. To overcome the limitation, this paper proposes a novel real-time voltage and frequency compensation strategy to suppress the fluctuations. The proposed strategy realizes voltage regulation by an adaptive virtual impedance loop and realizes frequency regulation by a virtual frequency-impedance loop. The novel real-time strategy is simple to be implemented and needless of communication; therefore, it is much more suitable for the PV-based MG. Finally, a PV-based MG is established as laboratory prototype, and experimental results validate the effectiveness of the proposed method.