Individual Pitch Angle Control of a Variable Speed Wind Turbine Using Adaptive Fractional Order Non-Singular Fast Terminal Sliding Mode Control

Pitch angle control strategy has been applied to mitigate the influence of mechanical load and also output power control at above-rated wind speeds. In this paper, a wind turbine is modeled based on simplified two-mass model and an adaptive fractional-order non-singular fast terminal sliding mode controller (AFO-NFTSMC) is proposed based on individual pitch control strategy to control pitch angle of wind turbine against uncertainties and external disturbances. To do this, the single-blade approach is used and the wind turbine is divided into aerodynamics and mechanical subsystems and governing equations of each subsystem are derived. By designing and applying the AFO-NFTSMC to the two-mass model, system behavior is observed and simulated in terms of step and turbulent wind speed inputs. In addition, to verify the validity of the AFO-NFTSMC, the proposed controller is implemented in the FAST environment in which the wind speed profiles are generated using TurbSim. In order to analyze the environmental effects on the dynamic behavior of the system, the controller performance is explored in presence of parametric uncertainties. Simulation results reveal the priority and high-precision performance of the controller compared to conventional adaptive and adaptive sliding mode controller. Moreover, rotor speed tracking error is evaluated and demonstrated through different criteria.