Distributed optimal control of reactive power and voltage in islanded microgrids

The paper proposes a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without communication system. To realize the twofold objective, an improved small signal model is developed first to reconstruct the system input-output relationship, where the relationship is evaluated with sensitivity analysis. A state estimator is then constructed based on the new input-output relationship in order to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive power sharing and system voltage restoration. And the dynamic performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides the expected reliability and flexibility for optimizing the reactive power sharing and system voltages restoration.