Fixed-Time Integral Sliding Mode Control with Fixed-Time Nonlinear Disturbance Observer for MPPT of Wind Turbines

This paper develops a faster convergent and robust control scheme for maximum power point tracking (MPPT) of wind turbines under multiple challenges. The control objective is to maximize energy capture efficiency, while accommodating the increasing integration of on-site renewable energy, managing fluctuating power demand, and promoting consumer participation in energy production. The proposed approach employs a composite controller using a new fixed time nonlinear disturbance observer with a fixed time integral sliding mode control (ISMC) scheme. The proposed controller tackles aerodynamic disturbances and model uncertainties without knowing the nominal dynamics of the system. The proposed observer estimates the overall disturbances and forwards them to the composite controller for compensation and helps in alleviating the input chattering problem. In addition, the composite ISMC tracks the optimal rotational speed of the rotor within a fixed time without relying on the initial conditions. The closed loop system stability is rigorously analyzed using Lyapunov analysis, which guarantees the fixed time convergence of disturbance estimation error, the sliding surface variable, and the tracking error. Moreover, the analysis guarantees that the settling times of the all the above variables are independent of the initial conditions. Additionally, the simulation analysis validates the effectiveness of the proposed strategy by comparing it with the state-of-the-art method.