An Optimal Secondary Voltage Control Strategy for an Islanded Multibus Microgrid

In this paper, an optimal secondary voltage control (SVC) strategy has been proposed for an islanded multibus microgrid (MG). The proposed strategy consists of a multiobjective function, power flow equality constraints, and four sets of inequality constraints. The multiobjective function aims to achieve a compromise between multibus voltage regulation and reactive power distribution among voltage modulation units by taking full advantage of both droop-controlled and PQ-controlled distributed energy resource (DER) units in the MG. Power flow equations for an islanded MG with or without secondary frequency control were considered as equality constraints. The limits of DER capacities, bus voltages, power flows on distribution lines, and system frequency must be accommodated during the process of solving the proposed SVC control strategy iteratively using the primal-dual interior-point method. Finally, simulation results have been presented to validate the feasibility of the proposed optimal SVC strategy.