Study On Damage Identification And Vibration Control Of Wind Turbine Tower

In the development of large-scale and deep-sea wind turbines,the towers bear complex and diverse loads.Under the action of multiple complex loads,the tower will be damaged and vibrated.If damage detection and vibration control cannot be carried out in time,it will easily lead to structural damage and collapse of the wind turbine.In this paper,based on the strain mode theory,the damage identification of the fatigue crack at the root of the tower and the fracture of the bolt at the flange was studied,and the vibration of the tower was controlled by the tuned mass damper（TMD）and the structural interaction method.Lay the foundation for ensuring the safe and efficient operation of the wind turbine during the service period.The main research contents of this paper are as follows:Firstly,the structure analysis and force analysis of the tower were analyzed,and the wind speed time history was obtained through Matlab programming and GH Bladed simulation based on the wind load theory.Considering the convenience of wind load acquisition and application,the 16m/s turbulent wind load was calculated based on GH Bladed.Secondly,Solid Works was used to simplify the modeling of the wind turbine,and import it into Ansys Workbench for modal analysis.It is found that the difference between the first-order natural frequency of the wind turbine calculated by numerical simulation and theoretical analysis is very small,which is 0.472%,which verifies the reliability of the wind turbine model.Then,based on the strain modal theory,the damage identification of the fatigue crack at the root of the tower and the fracture of bolt at the flange were studied.It is found that the strain mode shape is highly sensitive to damage compared to the natural frequency and displacement mode shapes.On the basis of point optimization,strain relative deviation damage identification index and strain absolute deviation and its modified damage identification index were established respectively,which further improved the identification effect of the two damage types.Finally,combined with transient dynamic analysis and wind load data based on GH Bladed,the vibration control effect of TMD on the tower was verified.The results show that the peak displacement,peak acceleration and peak stress at the top of the tower decreased by 23.20%,21.07% and 38.51%,respectively.Furthermore,a new method for the vibration control of the tower with the column structure in the tower was proposed,and the influencing parameters was optimized.The results show that the peak displacement,peak acceleration and peak stress of the tower reduced by 20.44%,20.77%and 29.18%,respectively.The reduction of stress is beneficial to reduce the occurrence of damage such as root fatigue cracks and bolt fractures.