Research On Suspension And Switching Control Of Wind Electromagnetic Suspension Yaw System

Key disciplines and technical issues involved in renewable energy generation have been concerned widely under the background of the environmental pollution,especially with the fog weather getting worse.As a clean renewable energy with broad prospects,wind power has become the first development strategy in the developed countries.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,and the suspension control and mode switching of MYS are studied.The main contents of this paper can be summarized as follows:1)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,a NDOB-based robust controller is designed via backstepping technique 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.Finally,the extensive simulation results show that the proposed robust controller has a good robustness and the MYS can realize smooth and reliable operations in its levitating and landing process,therefore the novel robust controller is substantiated to be effective and feasible.2)Due to the MYS will switch between dynamic suspension and yawing suspension during its operation,it is important to research the switching stability of the MYS.Two operating modes of MYS are considered in this paper,that is,the dynamic suspension subsystem and yawing suspension subsystem.In order to ensure the stable operation of the subsystems,first of all,the controllers of subsystems are designed via backstepping.However,the stability of subsystems cannot guarantee the stability of switching system.Thus,the switching rule is designed by average dwell time to meet the stable operation of MYS.Finally,the effectiveness of the proposed method has been proved by the simulation results.