Distributed Secondary Robust Controller Design for Islanded Microgrid in the Presence of Load Uncertainty and Nonlinear Terms

Abstract

This paper presents a novel distributed method for the secondary voltage control of islanded microgrids. To achieve consensus-based voltage control of distributed generation (DG) units within the microgrid structure, a new robust technique is proposed, rooted in a nonlinear approach and Lyapunov stability criterion. Specifically, error dynamics are first defined, leading to the design of a robust controller aimed at tracking the reference frequency. Subsequently, inspired by the design principles of the backstepping approach and leveraging Lyapunov stability theory, a robust tuner is developed to regulate the voltages of various DGs in the microgrid system. Beyond offering a simultaneous distributed control framework for both frequency and voltage, the proposed method ensures robust performance by guaranteeing high-speed convergence of the closed-loop system response. This is achieved through the proof of consensus finite-time Lyapunov stability. A key contribution of the proposed combined strategy is its inherent ability to effectively mitigate the adverse effects of disturbances and load changes within the microgrid. The efficacy of the method is rigorously evaluated through comprehensive simulations conducted in the MATLAB environment. Simulation results, even under worst-case scenario conditions, demonstrate the superior efficiency and resilience of the proposed control scheme, highlighting its potential for practical deployment in challenging islanded microgrid operations.