Abstract: Considering the performanceof microsources equipped with energy storage devices in an islanded-mode microgrid, an adaptive inverse control strategy applied to active power conditioning is developed. Regarding the P-f droop curve as a controlled object, the primary ideology of this method focuses on building an inverse function of the controlled object as a previa controller by using a digital filter with variable weight coefficients, with which a P-f slope coefficient can be obtained to modify the P-f droop curve. For a given microgrid in which unbalanced active power exists, this strategy can quickly find the best P-f slope coefficient along the negative gradient direction of the mean square error. Through the controlling process, the unbalanced active power among different microsources can be redistributed and the frequency of the microgrid can be preserved at the rated value. The validity and feasibility of this control strategy are verified by the simulation of a two-DG microgrid.

Key words: microgrid, microsource, P-f droop characteristic, adaptive inverse control, zero-error frequency regulation