Distributed control scheme for accurate reactive power sharing with enhanced voltage quality for islanded microgrids

This study presents a distributed control scheme for islanded microgrids to eliminate power sharing errors as well as frequency and voltage deviations based on distributed cooperative control. A consensus algorithm is developed through adaptive regulation of the virtual impedances for accurate power sharing regardless of load variations. The proposed power sharing controller is quite easy to implement with only one simple integral gain. It is achieved without using information about the feeder impedances, load powers or detailed microgrid structure. To remove the deviations in the frequency and voltage magnitude, conventional droop equations are enhanced by adding compensating signals, which are simply determined from the neighbors' droop information without a PI controller. Therefore, the control complexity is significantly reduced. The control performance is theoretically analyzed using a small-signal state-space model to evaluate the system dynamics and stability. A digital simulation is done using PSIM, and experiments are carried out with a scaled-down microgrid prototype to verify the proposed scheme.