Voltage Containment and Reactive Power-Sharing in Microgrids: Centralized and Distributed Approaches

In this article, a secondary voltage controller is proposed for ac microgrids, which ensures proportional reactive power-sharing among the distributed energy resources while their voltages stay within limits. The control objectives are formulated and analyzed as the steady-state control objectives, achieved by a nonlinear secondary controller for the energy resources. Both centralized and distributed forms of the proposed controller are presented, and the closed-loop system equilibrium and stability are discussed briefly. We show that the steady-state control objective is always achieved, if it is feasible. The effectiveness of the controller for different case studies is validated by adapting it to a microgrid system, based on the Conseil International des Grands Réseaux Electriques (CIGRE) benchmark MV distribution network.