An Accurate Autonomous Islanding Microgrid Reactive Power, Imbalance Power and Harmonic Power Sharing Scheme

To address inaccurate power sharing problems in autonomous islanding microgrids, an enhanced droop control method through adaptive virtual impedance adjustment is proposed. First, a term associated with DG reactive power, imbalance power or harmonic power is added to the conventional real power-frequency droop control. The transient real power variations caused by this additional term are captured to realize DG series virtual impedance tuning. With the regulation of DG virtual impedance at fundamental positive sequence, fundamental negative sequence, and harmonic frequencies, an accurate power sharing can be realized at the steady-state.