Analysis On Dynamic Characteristics Of Wind Turbine Main Bearing Under The Extreme Wind Speed

Wind turbine maximize the conversion of wind energy into human usable energy to alleviate energy shortages.As the key component of the wind turbine drive system,the main bearing absorbs most of the aerodynamic loads of the impeller.The operating state of the wind turbine is suddenly changed under the extreme wind speed,and the internal dynamic characteristics of the main bearing change significantly,which threatens the transmission efficiency,safety and reliability of the wind turbine transmission system.In this paper,the main bearing of megawatt wind turbine is taken as the research object,and the dynamic characteristics of the main bearing's internal structure under extreme wind speed are analyzed.Firstly,the extreme wind speed is simulated by using probability density function and simulation software,and the extreme wind speed load curve is obtained.Based on Betz theory and Blade element momentum theory,the load condition of the wind turbine spindle under extreme wind speed load is analyzed,and the complex wind speed load is decomposed.Secondly,based on the basic theory of finite element modal analysis of rolling bearing,the vibration state of main bearing is analyzed,and the finite element model of main bearing of wind turbine is established.The modal analysis of the main bearing under the free state and the actual working state constraint is carried out,the constraint has great influence on the whole mode of the main bearing,providing the basis for the dynamic analysis of the main bearing.Finally,based on modal analysis,the dynamic characteristics of main bearings of fans are further analyzed by using dynamic analysis software.The change rules of the equivalent stress of the inner and outer ring raceway and rolling body under extreme wind speed are analyzed respectively,and the main bearing outer ring raceway is the easiest to fatigue failure under alternating load.The equivalent stress change law of the joint unit of the main bearing rolling body of the wind turbine with different speed is analyzed,and is compared with the equivalent stress of the joint unit of the main bearing rolling body under the extreme wind speed.The influence of spindle speed on the dynamic characteristics of main bearing of wind turbine is studied,the increase of rotational speed will have an effect on the equivalent stress of rolling body and outer ring.The changes of dynamic characteristics of the main bearing in normalwind speed and extreme wind speed working conditions of wind turbine are compared,the results show that under extreme wind speed,the vibration of main bearing is aggravated,and roller is easy to slip phenomenon at the abrupt change of speed.In this paper,the finite element analysis method is used to study the dynamic characteristics of the wind turbine under the extreme wind speed,which makes up the neglect of the theoretical calculation for the actual working conditions,and provides a theoretical basis for the optimization design and fault diagnosis of the main bearing of the wind turbine,and has a guiding significance for the practical application of the engineering.