A Deviation Elimination Control Based on Autonomous Current-Sharing Controller for the Parallel-Connected Inverters in AC Microgrids

Conventional autonomous current-sharing controller (ACSC) will induce inevitable frequency and voltage magnitude deviations due to the output currents and virtual impedances. Thereby secondary control has been proposed to restore the frequency and voltage magnitude deviations by using communication links. In this paper, an autonomous deviation eliminative control method is proposed for the parallel-connected inverters in AC islanded microgrids in order to simplify the control scheme and to improve power quality and control reliability. Two high-pass filters are included in synchronous-reference-frame virtual impedance loop and are activated in steady-state operation to attenuate frequency and voltage magnitude deviations, meanwhile maintaining the autonomous current-sharing performance among the parallel inverters. Simulation results based on two parallel-connected voltage controlled inverters from Matlab/Simulink verify the effectiveness of the proposed approach in different scenarios.