Research On Vibration Suppression Control Strategy Of Double-fed Wind Power System Drivetrain

Doubly-fed wind power system is a mainstream large wind turbine.The drivetrain,as a key component of the wind turbine,works in harsh environments such as flexible tower support and impact load,as well as complex working conditions such as start and stop,yaw,variable propeller and regulation.Its vibration characteristics directly affect the safety,reliability and service life of the wind turbine.The clearance of the gearbox and the elasticity of the coupling are the key factors to generate the vibration of the drivetrain.Therefore,the effective suppression of the clearance vibration of the gearbox and the elastic vibration of the coupling is significant for the stable and safe operation of the drivetrain of double-fed wind turbines.In view of this,on the basis of extensive research and analysis of domestic and foreign research status,this paper carries out research from the multi-mass modeling of the drive train of doublyfed wind power system,vibration suppression strategy based on pitch control,vibration suppression strategy based on doubly-fed generator speed control and other aspects.The main research work is as follows:A multi-mass model of the drivetrain of doubly-fed wind power system with gear clearance and coupling elastic coefficient was established to provide a model basis for different vibration suppression strategies.Firstly,the basic structure of drivetrain of doubly-fed wind turbine is analyzed.Secondly,considering the factors of gear clearance and coupling elasticity,the twomass,three-mass and four-mass drivetrain models were established respectively.Finally,based on the models of different mass blocks,the generation mechanism of gear clearance vibration and coupling elastic vibration and the vibration suppression scheme are analyzed.Aiming at the clearance vibration of drivetrain gears,the clearance nonlinear link was decomposed into a linear link and a bounded disturbance link,and the suppression strategies were researched from the perspective of pitch control by using Internal model control and disturbance observer.Taking two-mass block and three-mass block drivetrain as the research object,internal model control method is proposed to suppress gear clearance vibration: Firstly,a method to suppress the nonlinear vibration of gear clearance is proposed by using one-degreeof-freedom internal model control.Then,a two-degree-of-freedom internal model control method is used to solve the problem that the one-degree-of-freedom internal model control cannot independently adjust the output tracking performance and anti-disturbance performance of the system.Finally,the two-degree-of-freedom internal model control is improved to solve the problems of structure inconsistency and design difficulty.Taking the four-mass drivetrain as the object,a perturbation observer is adopted to suppress the vibration of gear clearance,so as to solve the problem that the internal model control can not be used to suppress the vibration of the four-mass and above models: First determine the nominal model of the system,and then based on the nominal model,according to the requirements of the system’s performance indicators,design a suitable outer loop controller,and finally determine the structure of the lowpass filter and the order of the numerator and denominator,and add the low-pass filter into the control system.Aiming at the elastic vibration of drivetrain coupling,the passive and active suppression strategies were studied by using inverse Quasi-Proportional Resonant(QPR)controller and parametric adaptive PID controller respectively from the Angle of pitch control.In terms of passive suppression strategy,the inverse QPR controller based on resonant amplifier principle was proposed to solve the problems of notch depth and bandwidth of common notch filters.In terms of active suppression strategy,it is difficult to determine the controller parameters of the conventional PID strategy for the elastic vibration suppression of the multi-mass drivetrain.Taking the two-mass drivrtrain as the object,internal model control is used to realize the adaptive tuning of PID parameters.Taking the four-mass drivetrain as the object,particle swarm optimization is used to realize the adaptive tuning of PID parameters.Aiming at the gear clearance vibration of the drivetrain and the elastic vibration of the coupling,the suppression strategy of the doubly-fed generator speed control is researched by using 3-DOF-IMC.Considering that the wind power system working in the maximum wind energy tracking area controlled by constant pitch cannot suppress vibration by adjusting pitch Angle,a collaborative suppression strategy of chain gear clearance vibration and coupling elastic vibration was proposed from the torque(speed)control side of doubly-fed generator.Firstly,the function of 3-DOF-IMC in the control of voltage decoupling,tracking performance,anti-disturbance performance and robust performance of the generator is analyzed.Then,the inhibition ability of the feedback filter to the periodic disturbance signal is studied.Finally,the controller with three degrees of freedom is designed respectively to realize the vibration suppression of the drivetrain.