Distributed robust secondary control of islanded microgrid with stochastic time-varying delays and external disturbances

In the islanded microgrid (MG) with multiple distributed generation units (DGs), the stochastic time-varying communication delays and external disturbances have a great impact on its operation. In this paper, we propose a distributed secondary robust control to realize the robust stability of voltage and frequency. First, a small-signal model is built for a single DG unit, and then the global closed-loop state-space model for MG is derived. Afterward, a new Lyapunov–Krasovskii functional is introduced to analyze the robust stability of the MG. According to the proposed stability theorem, a controller design method optimizing the robust performance of the MG system is presented. Lastly, we verify the correctness of the robust stability theorem and the validity of the controller design method by simulation.