Research On Modeling And Control Of Magnetic Levitation Yaw System Based On Model Predictive Control

Yaw system is an important component of medium-and large-scale horizontal axis wind turbine.In order to maximize the utilization of wind energy and improve the working efficiency,the wind turbines should be placed in an upwind position.But the traditional yaw system has many shortcomings,such as complicated structure,large space occupation,high failure rate and inconvenient maintenance.Once a fault occurs,it is difficult to replace the yaw system,and the maintenance time is long,which has a serious adverse effect on the normal operation of the entire power grid.Therefore,it is urgent to develop a new yaw system with low power consumption,high reliability,and high wind precision.To this end,we proposed a novel wind maglev yaw system(MYS).Based on the model predictive control(MPC)theory,this paper aims to the modelling and control for the suspension process and yaw process of the MYS.First,according to electromagnetism and mechanics theory,the nonlinear dynamic model of the suspension process of MYS is established,and the Taylor series expansion is carried out to approximate the linear model of the suspension process near the equilibrium point.At the same time,electromagnetic and kinetic theories are used to analyze the yaw process of the MYS,and the mathematical model of the yaw process is established.Second,according to the above models,the outer ring air gap predictive controller is designed with the predictive control theory based on the equation of state.The inner ring adopts the traditional PID control,and the closed-loop state space equation of the suspension process is derived by using the method of undetermined coefficients.Considering that the parameters of the MYS are easily affected by the external environment and temperature during the levitation process,a model mismatch compensator is designed,and the feasibility of this scheme is verified by simulation.Third,in order to further improve the anti-interference ability and dynamic response ability of the suspension process of the MYS,PID control and state feedback control(SFC)are combined as the outer loop controller of air gap,and the finite set model predictive control(FCS-MPC)with delay compensation is used as the inner loop controller of current.Then the proposed control scheme is compared with the traditional PID control by simulation,and the results show that the proposed controlscheme has stronger anti-interference ability and faster dynamic response.Fourth,based on the FCS-MPC theory,the predictive current model of the yaw process of the MYS is designed.Simulation based on MATLAB/Simulink is carried out to verify the feasibility of the proposed scheme.Finally,the MYS experimental platform based on dSPACE was built,and the peripheral hardware circuit design of DS5203/DS4002 was completed.