Modeling of Maglev Yaw System of Wind Turbines and its Robust Trajectory Tracking Control in the Levitating and Landing Process Based on Ndob

Abstract

Abstract The yaw system is one of the important parts of the horizontal axis wind turbines. In this paper, a novel maglev yaw system (MYS) is introduced, a novel robust controller based on nonlinear disturbance observer (NDOB) is proposed to improve the dynamic suspension stability of the MYS in its levitating and landing process. First, the dynamic model of the MYS is built and analyzed as well as the model of the force caused by crosswind exerting on the MYS, and then the mathematical model of the MYS is derived from its dynamic model. Second, since the uncertain internal disturbance originated from the MYS itself exists, in order to realize the finite time convergence and improve the robustness of the MYS, a NDOB‐based robust controller is designed via like nonsingular terminal sliding mode (LNTSM) method with the aid of backstepping design idea (BDI) to guarantee that the system output asymptotically tracks the reference trajectory, and the levitating and landing velocities of the MYS converge to their expectations globally and asymptotically in finite time. Finally, compared the conventional backstepping control (BC), the extensive simulation results show that the proposed robust controller has a better robustness and the MYS can realize smooth and reliable operations in its levitating and landing process in finite time, therefore the novel robust controller is substantiated to be effective and feasible.