Integral Sliding Mode-Composite Nonlinear Feedback Control Strategy for Microgrid Inverter Systems

Abstract

To enhance the dynamic performance and robustness of the voltage control system of islanded microgrid inverters, a new control strategy combining integral sliding mode (ISM) control and composite nonlinear feedback (CNF) control is proposed. In ISM control, firstly, a new reaching law is designed to improve movement quality in the reaching phase by improving the power term and introducing the inverse tangent function. Then, to improve disturbance observation accuracy, a variable gain extended state observer is designed by improving the regulation mechanism of the state variables according to deviation control. Using the idea of variable damping, linear and nonlinear feedback are combined into CNF control. Specifically, linear feedback provides a small damping ratio for faster system response, while nonlinear feedback increases the damping ratio to improve steady-state performance. Simulation results show that the integral sliding mode-composite nonlinear feedback (ISM-CNF) control strategy cam balances convergence speed and chattering better and achieves higher steady-state accuracy than conventional strategies. Moreover, ISM-CNF control has better robustness to reference voltage variations and disturbances caused by sudden load changes. Therefore, the ISM-CNF control strategy can accomplish voltage control of islanded microgrid inverters quickly and steadily, effectively suppressing system disturbances and enhancing stability and power quality. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.