Research On The Control Of Wind Electromagnetic Levitation Yaw System

This paper mainly studied the control problems of the magnetic levitation yaw system of the horizontal axis wind turbine.The device is different from the control problem of traditional wind turbine yaw system,the traditional yaw system only needs to control the yaw motor to realize yaw,however,the yaw control system of the maglev yaw system includes both suspension and yaw control,which needs to complete levitation of the nacelle first,and then drive the yaw motor to realize yaw,after yaw finished,the nacelle needs to be driven down,so it is a little difficult,the four aspects are studied as follow.First,this paper studied the development status of wind power yaw system and the composition and working principle of the yaw system of magnetic levitation,based on the structure and principle,this paper analyzed the fundamentals reasons of high reliability,low failure rate and long service life of the magnetic levitation yaw system,the table of performance analysis of the magnetic levitation yaw system and the conventional yaw system was given,which clearly showed the superiority of the system as the wind yaw system and the magnetic levitation yaw system,the relevant control problems were also studied.Second,this paper modeled the mathematical model of the magnetic levitation yaw system,and analyzed its stability;advantages and disadvantages of the control when the voltage or current was selected as the system control input were analyzed.Two types of common suspension chopper circuits:Buck circuit and the two-quadrant DC H-bridge circuit were analyzed;the analysis and comparison showed that the two-quadrant DC H-bridge circuit can regulate the current faster.The state feedback method,the optimal quadratic regulator method and PID controller were used to simulate the magnetic levitation yaw system to realize its stabilization,the PID controller used a simple method to adjust the PID controller parameters:K_p,K_i,K_d.Because the above control method had some defects,a multi-variable state feedback controller based on air gap variation is proposed and simulated,the result proved the effectiveness of the method.In order to simulate the actual working conditions,a two-quadrant H-bridge circuit and magnetic levitation system simulation platform was built,and the simulation result was analyzed.Third,for the yaw state of the yaw system of the maglev of the wind turbine,according to the wind torque,the yaw states were divided into three modes:first,the wind torque T_W was less than the required driving torque T_N of the nacelle;second,the wind torque T_W was bigger than the T_N,but less than the 2 T_N's work condition;third,the wind torque T_W is bigger than twice the the T_N,mathematical model was modeled separately.The damping problem of the wind turbine magnetic levitation yaw system was studied,the control simulation and simulation results under the three modes were carried out,the results show that the system can automatically control the yaw damp.Then,a non-yaw sensor algorithm for this system was proposed,this method can remove the yaw sensor and simplified the structure of the yaw system.The simulation of wind-electromagnetic levitation yaw motor control was studied,the yaw simulation platform was built by using rotor field orientation method,sliding mode speed controller and SVPWM algorithm,the effectiveness of the control method designed for this device was verified by experiments.Finally,the suspension control circuit and the yaw control circuit are designed and built.The DSP28035 of Texas Instruments is used as the main controller to control the levitation state and the yawing state of the magnetic levitation yaw system.