Impact of Secondary Control Design on the Microgrid Domain of Stability Considering Reactive Power Sharing

The basic objective of microgrid primary control is to preserve microgrid stability. On the other hand, microgrid secondary control has been proposed for ensuring reactive power-sharing and restoring the frequency and voltages of the microgrid. Therefore, this paper presents a complete model for evaluating the combined impact of primary and secondary control actions on microgrid domain of stability since the impact of the secondary control design on the domain of stability of the microgrid has not been addressed. Further, the developed model is used to assess the impact of reactive power-sharing, secondary controller design parameters, and communication delay on the domain of stability of the microgrid. The domain of stability is a supportive tool for determining the stable operating range for different microgrid droops. Simulation results have been obtained to validate the developed model and the domain of stability analysis. These results demonstrated that secondary control actions have a significant influence on the domain of stability of the microgrid, and thus it is important to consider the secondary control design in the determination of the microgrid's stable range. Moreover, it has been demonstrated that primary control gains can be severely constrained by reactive power sharing gains.