Bifurcation Analysis And Bifurcation Control Research Of Wind Turbine Drive System

In recent years,China’s wind power industry has developed rapidly.In 2015,China has the largest installed capacity of wind power equipment.Gansu Province is located in an important location in the northwest,especially in the Hexi area with flat terrain open Gobi Desert,which is suitable for the construction of large wind farms,and has the world’s largest wind power base-Gansu Jiuquan 10 million kilowatt-class wind power station.But due to the impact of the special climate in the northwest such as the wind and other natural environment,the requirement of wind turbine hardware is becoming more and more complex.Therefore,the design level and the manufacturing capacity of the wind turbine system model of Gansu Province have a higher requirement.Establishing the dynamic model of wind power generation transmission system correctly and analyzing the factors that affect the normal operation of wind turbines and the laws of motion is an important part of the design of wind turbine transmission system.Therefore,for this research work which has great practical significance,improving the design and control capacity of Gansu Province wind turbine transmission system has a very important significance.Based on the bifurcation theory of nonlinear dynamical systems,stability theory and multi-scale method theory,the wind power generation model under several different forces is analyzed in detail,especially for the bifurcation phenomenon and bifurcation control,the main contents are as follows:1.This paper summarizes the development process of wind turbine transmission system and its research status at home and abroad,the purpose and significance of the topic and the existing problems in this field are put forward,then some basic concepts of nonlinear dynamics are introduced,such as Flip bifurcation,Hopf bifurcation and so on.Then the method of bifurcation control and multi-scale method are briefly introduced.2.Through theoretical overturning and numerical simulation,the dynamic behavior of the wind turbine transmission system with nonlinear damping is studied.Firstly,the nonlinear dynamic model of wind turbine is introduced.Secondly,the multi-scale method is used to derive the theoretical derivation and the analysis of stability of the wind turbine transmission system with nonlinear damping,and Hopf bifurcation condition is obtained.Finally,the time doubling bifurcation of the system is simulated numerically,The influence of nonlinear damping term and other factors on the stability of wind turbine is obtained.3.The stability analysis and bifurcation control of the wind turbine transmission system with nonlinear stiffness are studied.First the dynamics model of this chapter is introduced.Secondly,Then the multi-scale method is used to obtain the bifurcation response equation of the system in Cartesian coordinate system.Thirdly,by adjusting the delay parameters of the system,the original system and the controlled system are controlled separately,the influence of the delay parameter on the stability can be seen.Finally,the time-doubling bifurcation and Hopf bifurcation of the original system are simulated numerically,not only the correctness of the theoretical derivation could be verified,it also shows that the dynamical characteristics of the wind turbine transmission system with nonlinear stiffness are doubly periodic and Hopf bifurcation.4.The bifurcation behavior of wind turbine transmission system under combined harmonic excitation is studied.First the dynamics model of this chapter is introduced.And then use the multi-scale method to solve the wind turbine transmission system,the bifurcation condition of the wind turbine transmission system under the combined harmonic excitation is studied,which proves the stability of the system.The dynamic characteristics of the wind turbine transmission system are analyzed under the coupling of different factors and combined harmonic excitation.Finally,through the numerical simulation,on the basis of verifying the correctness of the theoretical results,it is shown that the wind turbine transmission system under the combined harmonic excitation has complicated dynamic characteristics of doubling period and Hopf bifurcation.