A Discrete-time Robust Adaptive Second-Order Sliding Mode Controller for Grid-connected Power Systems with LCL Filter

This work presents a novel discrete-time robust adaptive super-twisting sliding mode (STSM) controller, which is based on the robust model reference adaptive control theory. The controller is used to regulate the currents of a grid-connected three-phase full-bridge voltage-source static inverter with an LCL filter. The proposed control strategy provides enhanced performance to the grid-tied power system by incorporating robustness to unmodeled dynamics and the ability to handle grid uncertainties. The effectiveness of the proposed controller is validated through reliable simulation results in PSIM, which consider the inverter modulation, synchronization of the controller with the grid voltages using the Kalman filter, and grid inductance variation.