An Improved Reactive Power Sharing in an Isolated Microgrid with a Local Load Detection

Abstract

Accurate reactive power sharing is one of the main issues in isolated microgrids to avoid circulating currents and overloading small distributed generation (DG) units. A simple and enhanced method for improving reactive power sharing among parallel-connected DG systems in an isolated microgrid was proposed. The proposed method uses a compensator term with an integral action to minimize the reactive power-sharing error internally without any need for communication or information shared among the DG units. Moreover, a small disturbance carrying part of the reactive power-sharing error is injected into the active power-droop controller, maintaining the essential system parameters within their allowable limits. Consequently, a simple compensation trigger system is proposed to effectively detect any local load change in the network and provide compensation gains to activate the proposed control method. The stability of the proposed method was verified and analyzed using a detailed small-signal model. Moreover, the effectiveness and robustness of the proposed method were validated through comprehensive simulation studies and comparisons with other related techniques.