Secondary Control for Power Sharing in a Standalone Microgrid under Unequal Feeder Impedance and Complex Loads

Abstract

AC Microgrids (MG) play significant roles in maintaining the stability of the conventional power system. A MG may contain linear, nonlinear and unbalanced loads whose nature of energy consumption can result in distorted voltage causing system instability. In the MG, the discrepancy in feeder impedance and complexity of loads results in poor power sharing. Therefore, this research focusses on the poor power sharing arising from the above stated conditions. The hierarchical control consisting of the proportional integral resonance (PIR) and adaptive virtual impedance-based compensation primary and secondary control for power sharing in a stand-alone AC MG is proposed and verified in MATLAB/Simulink. The results demonstrate that the DG units in the MG achieve balanced power sharing in transient and steady-state operation despite the difference in feeder impedances. In addition, a slight deviation in frequency and voltage magnitude caused by the conventional droop control is restored using the secondary control.