Feasible Range and Optimal Value of the Virtual Impedance for Droop-Based Control of Microgrids

Abstract

This paper presents a systematic method to determine the feasible range and optimal value of the virtual impedance of the droop-based control to enhance a microgrid system performance with respect to power decoupling, reactive power sharing, system damping, and node voltage profile. A modified power flow analysis and an augmented small-signal dynamic model of the droop-based controlled microgrid, considering the impact of the virtual impedance, are developed. Subsequently, based on the developed methods, the feasible range of the virtual impedance, which can satisfy all the system performances requirements, is determined and presented. Based on a particle swarm optimization technique, an optimization process is introduced to select a virtual impedance value within the feasible range to achieve the overall optimal microgrid performance. Finally, simulation results in the PSCAD/EMTDC platform are provided to validate the feasibility and effectiveness of the proposed methods.