Harmonic current filtering and resonance damping have become important concerns in the operation and control of the islanded microgrids. To address these challenges, this paper proposes a control method for the inverter-interfaced Distributed Generation (DG) units, which can autonomously share the harmonic currents and resonance damping burdens. The approach employs a load compensator, which is based on the decomposition of output current, in addition to the outer droop-based power controller as well as the inner voltage and current controllers. The load compensator consists of a virtual fundamental impedance loop for the enhanced reactive power sharing, and a variable harmonic impedance loop which allows to counteract the harmonic voltage drops across the grid-side inductance of DG inverter and also to dampen out harmonic resonance propagation in the microgrid. Lastly, the laboratory tests on a three-phase islanded microgrid setup are carried out to validate the performance of the proposed control scheme.
I E E E Transactions on Industry Applications, 2014, Vol 50, Issue 1, p. 452-461