Quadratic-Droop-Based Distributed Secondary Control of Microgrid With Detail-Balanced Communication Topology

This article proposes a quadratic-droop-based fixed-time distributed secondary voltage control of an islanded ac microgrid. The microgrid consists of inverter-based distributed generators, connected over a detail-balanced communication topology with bidirectional unequal edge weights. The proposed voltage restoration strategy is derived from the quadratic relation between voltage and reactive power for inductive microgrids against their linear dependence, which has been conventionally used in designing voltage droop controllers. It has been illustrated that the proposed quadratic-droop-based control design strategy shows better performance as compared with the linear counterpart. We provide a rigorous Lyapunov stability analysis for the proposed controller and also obtain an upper bound on the convergence time, independent of the system's initial conditions. In addition, frequency restoration and proportional active power sharing among the generators are realized in the fixed time. Simulations are provided to verify the efficacy of the proposed controllers, including a comparative analysis with conventional droop control and finite-time control through a case study.