Optimum efficiency control of a wind turbine with unknown desired trajectory and actuator faults

Abstract

The operational wind turbine efficiency in the power maximization regions and reliability improvement to reduce the produced power cost can both be enhanced by using an appropriate controller to cope with the highly nonlinear behavior of wind turbines in the presence of wind speed variation and actuator faults. In this regard, a nonlinear controller is proposed to make the wind turbine operate effectively despite some of the actuator faults, similar to the fault-free case. The considered actuator faults are pitch and generator actuator biases, as well as pitch actuator dynamic change, including pump wear, hydraulic leak, and high air content in the oil. Also, the wind speed is assumed to be an unmeasurable disturbance, and, accordingly, when using the neural network scheme, the unknown desired trajectory is reconstructed, so that the captured power is maximized. The proposed controller is shown to be able to keep the wind turbine tracking the reconstructed desired trajectory with sufficient accuracy. By using the Lyapunov analysis, the boundedness of the closed-loop system with the proposed controller is proven. The designed controller is verified via numerical simulations. The effectiveness of the proposed controller is evaluated in comparison with industrial constant gain controller results.