An enhanced power sharing strategy for islanded microgrids using adaptive virtual impedances

In this paper, an enhanced power sharing strategy employing adaptive virtual impedances for Q-ω and P-V droop-based islanded microgrids (MGs) is proposed. The proposed scheme improves the performance of dynamic response and system stability while accurate power sharing is obtained. The low-bandwidth communication is utilized to send the power commands. The adaptive virtual impedances consist of a resistor tuned by active power deviation and a complex impedance component tuned by reactive power deviation. And the former is to realize accurate active power sharing while the latter is to improve dynamic response and system stability. Meanwhile, the output current delay method to realize the virtual complex impedance is presented, avoiding the differential operation, which has high sensitivity to noises. Simulation results of a MG containing two distributed generation (DG) units with complex feeder impedance are presented to investigate the validity of the proposed strategy.