A Dual-Frequency-Droop Based Nonactive Power Sharing Control Method for AC Microgrids

Droop control has the advantages of realizing active power sharing and reliable operation of each distributed generators (DG) in AC microgrids. However, the nonactive power generated by reactive load, nonlinear load and single-phase load cannot be shared among DGs under droop control, which may lead to overloading of certain inverters or even cause system paralysis. This paper proposes a dual-frequency-droop based nonactive power sharing control strategy for AC microgrids, which achieves active power sharing through active power-fundamental frequency droop, and achieves nonactive power sharing through nonactive power-injected harmonic frequency droop. A specific harmonic signal is deliberately injected by each DG to adaptively regulate the virtual impedance to realize nonactive power sharing. Simulation and experimental results have been provided to verify the effectiveness of the proposed strategy.