Autonomous Control of Inverter-Interfaced Distributed Generation Units for Harmonic Current Filtering and Resonance Damping in an Islanded Microgrid

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.