Fractional-order adaptive Type-3 fuzzy logic super-twisting sliding mode control algorithm for PMSG-based variable speed wind energy conversion system

Wind energy conversion systems present several sources of disturbances and uncertainties due to nonlinear and complex dynamics. These phenomena can negatively impact the expected behavior of the controlled system and, consequently, lead to a decrease in maximum power extraction. This study focuses on designing a novel fractional-order control method for permanent magnet synchronous generator-based wind turbine systems. To improve the control performance in the presence of external disturbances and parametric variations, the proposed approach combines the robust super-twisting sliding mode technique with adaptive Type-3 fuzzy logic systems. Resulting from the evolution of Type-2 fuzzy logic systems, the interval Type-3 provides better approximation capabilities, especially in the presence of a higher degree of uncertainties. Combined with the super-twisting algorithm, fuzzy systems are used both to approximate unknown nonlinear functions and to replace discontinuous control laws. The system stability is ensured by the extended fractional Lyapunov criterion. Furthermore, a new lemma is proposed to demonstrate the finite time convergence. A comparative study including other well-known control techniques is presented to validate the effectiveness of the proposed approach.