Study On Demagnetization Induced Vibration Mechanism And Vibration Control Of Megawatt Permanent Magnet Synchronous Wind Power Generator

The permanent magnet synchronous wind power generator（PMSWG）is a key component of wind power generation system.The demagnetization of PMSWG not only affects its own operation and the quality of system power generation,but also has a great impact on the normal operation of the wind power generation system and the service life of each component of the system.In this paper,the rotor dynamics modeling,vibration characteristics and vibration control of permanent magnet synchronous wind turbine under demagnetization fault are studied based on rotor dynamics theory.The main research contents include:（1）The unbalanced magnetic pull（UMP）on the demagnetized rotor of PMSM is studied,the demagnetized rotor dynamic model of PMSM is constructed,and the dynamic characteristics of the rotor permanent magnet under different demagnetization states are analyzed.Firstly,the dual rectangular coordinate system of stator and rotor is constructed.In the rotor rectangular coordinate system,the demagnetization state of the motor rotor is described quantitatively,and the magnetic density state of the eccentric air gap of the rotor is considered,so as to obtain the UMP on the rotor.Then,through coordinate transformation,the mathematical analytical model of the UMP based on the stator rectangular coordinate system is constructed.Secondly,considering the electromagnetic force of rotor under demagnetization fault and the nonlinear Hertz contact force generated by rolling bearing,the bearing-rotor-magnetic field coupling dynamic Jeffcott model of PMSM under demagnetization condition is established.Finaly,based on the Jeffcott model,the dynamic characteristics of PMSM rotor system under the quantitative change of permanent magnet demagnetization state are analyzed quantitatively.（2）Build the demagnetization rotor vibration test platform of PMSM,and complete the verification of the demagnetized rotor vibration.In order to realize demagnetization vibration test of rotor of PMSM,designs the block diagram of control system and vibration test system,and then completes the construction of demagnetization rotor vibration test platform in this research content.Then,based on the conclusion of theoretical research,complete the demagnetization setting of permanent magnet according to the change of angle,and test the rotor vibration characteristics of rotor of the PMSM under different demagnetization angle states.Finally,based on the data of the experiment,the change rules of fundamental frequency and related frequency doubling under different demagnetization angles is analyzed,and the theoretical simulation conclusion of research content（1）is verified,the demagnetization rotor dynamics model of PMSM is verified.（3）The electromagnetic actuator for rotor vibration control of WM PMSWG is designed,and the sampling control scheme of reversible demagnetization rotor vibration is proposed.Firstly,according to the hollow structure of the rotor shaft of the WM PMSWG,the electromagnetic actuator is constructed with the magnetic conductive material embedded in the inner wall of the rotor shaft as the rotor part and the eight-pole coil embedded in the inner shaft as the stator part.At the same time,considering the UMP effect of WM PMSWG rotor under demagnetization,the dynamic model of rotor system is constructed.Based on the dynamics model of rotor,the H_∞sampling control scheme is constructed according to the characteristics of the sensor sampling signal;The characteristics of the system model and the sum of the bilateral sampling intervals[t _k,t)and[t,t_k（10）1)of the system is sufficient considered,the Lyapunov functional is constructed,and the sufficient conditions for the existence of the sampling controller for the demagnetization rotor system of the WM PMSWG are obtained by using the Lyapunov stability theory and the LMI processing method.At the same time,considering the influence of system sampling delay,the delay sampling control scheme is constructed.By using Lyapunov stability theory and LMI processing method,the sufficient conditions for the existence of delay sampling controller for the demagnetized rotor system of WM PMSWG are obtained.Finally,the effectiveness of the control algorithm is proved by the parameter simulation of the MW PMSWG.（4）A time-delay sampling control scheme for demagnetized rotor vibration of WM PMSWG is proposed.For the demagnetization vibration of MW PMSWG rotor,the active vibration control of MW PMSWG rotor based on sampling time-delay control is studied.Firstly,based on the rotor dynamics theory,considering the UMP caused by demagnetization of rotor permanent magnet,the rotor system dynamics model is constructed.Based on the rotor dynamics model,considering the time delay caused by the actual sensor sampling signal transmission and controller calculation,using Lyapunov stability theory and LMI processing method,the conditions for periodic sampling and vibration suppression control of demagnetized rotor of MW PMSWG are established.Finally,the effectiveness of the control algorithm is proved by the parameter simulation of the MW PMSWG.