Pitch Blade Regulation of Wind Turbines Using Dynamic Sliding Mode Control and Nonlinear Sliding Observer

Wind turbines (WTs), particularly those with two-shaft drivetrain and variable speed, present a complex model. This study initially shifts all WT variables to the low-speed shaft. Subsequently, the Taylor series for the torque is generated by the wind, or rotor torque, is computed near the optimal blades pitch angle and the optimal blades tip speed ratio (TSR). At these optimal points, wind power extraction is maximized, i.e. maximum power point tracking (MPPT) is achieved. The paper introduces two novel state feedbacks and derives a linear model with uncertainty, represented by a new input variable. This uncertainty can lead to mechanical stress, particularly if the new input variable lacks smoothness. To address these issues, a robust sliding mode controller using a dynamic approach (D-SMC) is employed, which eliminates chattering through a low-pass integrator. The sliding surface dimension in D-SMC exceeds with respect of the original system, necessitating the estimation of this newly introduced state. Therefore, the paper proposes a new sliding observer with a nonlinear approach (NSO). The stability of the both D-SMC and NSO is verified using Lyapunov theory. The superiority of D-SMC is demonstrated by comparing to the conventional sliding mode controller (C-SMC) under identical NSO and simulation conditions.

کلیدواژه ها:

Nonlinear sliding observer ، pitch angle control ، Sliding mode control ، Wind turbine