MPPT Performance and Power Quality Improvement by Using Fractional-Order Adaptive Backstepping Control of a DFIG-Based Wind Turbine with Disturbance and Uncertain Parameters

This paper proposes a fractional-order adaptive backstepping control (FOABC) with disturbance and uncertainty terms compensation for improving the MPPT (maximum power point tracking) performance and output power quality of a doubly fed induction generator (DFIG)-based wind turbine. In the proposed high-efficacy controller, disturbance and uncertainty terms are estimated in real time using an adaptive estimator designed using a recursion design process based on the nonlinear backstepping control. Meanwhile, a robust compensator is schemed and incorporated into the backstepping control algorithm so that it suppresses the effects of external disturbances and system uncertainties and, as a result, ensures the maximum wind energy extraction as much as possible, which is usually well known as MPPT. Furthermore, the fractional-order control approach was deployed in the proposed adaptive backstepping controller to provide a smooth control signal for enhancing the quality of the power injected into the grid. The stability analysis of the overall closed-loop system was performed using Lyapunov's stability theory. The high effectiveness of the proposed control method was assessed through simulation studies carried out in MATLAB/Simulink of a DFIG-wind turbine operating in various conditions.