Advanced third-order super-twisting sliding mode control for enhanced control of grid-connected wind energy systems

Wind energy systems (WES) utilizing doubly fed induction generators (DFIG) face significant challenges due to nonlinear uncertainties and disturbances, necessitating an effective and robust control system to ensure smooth power transfer. A robust variant of sliding mode control (SMC), referred to as super-twisting SMC (STSMC), efficiently reduces chattering, enabling smooth and continuous power transfer. Despite its advantages, STSMC has some drawbacks, including limited disturbance rejection due to the nonlinear aspects of the variable reaching law and delays in the state space trajectory following disturbances. This paper proposes enhancing the reaching phase of STSMC by introducing a third-order STSMC (TO-STSMC), which improves disturbance rejection and further reduces chattering compared to the traditional STSMC. The proposed controller's stability is analyzed using Lyapunov theory for both the sliding and reaching phases. Extensive Matlab/SIMULINK simulations under various conditions are conducted to evaluate performance, and the simulation outcomes are validated with real-time experimental data using a Typhoon hardware-in-the-loop (HIL) setup.