Dynamic Characteristics Analysis Of Large Scale Wind Turbine Tower Under Time-varying Load

With wind power technology increasingly mature, the wind power stand out in avariety of new energy industry. Meanwhile, the height of tower is increasing as for the unitcapacity of wind turbine increased; the time variability and cross degeneration of gravityloads and aerodynamic loads have more significant impact. Therefore, the structuraldynamic analysis for Wind Turbine tower is a necessary work.In this paper, the object of study-3MW Wind Turbine tower (4.5m×3.0m×83.01m),which developed by Wind Energy Institute, Shenyang University of technology. Thedynamic behavior and fatigue characteristics of tower were studied based on the theoreticalanalysis and numerical simulation. According to IEC standards,3MW WT model isestablished by GH Bladed, the loads on the tower under operating conditions are achieved.The FEM of tower is built by using finite element analysis software ANSYS and MSC.Fatigue, then the simulated time-varying load is applied to the model for dynamics,stability and fatigue analysis. The main contents are as follows:Winds of different speeds under operating condition are simulated by using GHBladed, through which the loads at the top of tower are achieved by using coordinatetransformation. The natural frequency and mode shape of the wind turbine tower underdifferent boundary conditions are achieved, through the establishment of two differentmodels by ANSYS, and then the natural frequency of the tower is compared with bladerotation frequency, the little difference between them shows the unfavorable dynamicproperties of the tower. In the transient analysis, the stress-strain characteristics of thetower in the dynamic response are analyzed. The tower belongs to thin-walled defectstructure for a doorway was opened at the bottom. Three plans are considered to have thetower buckling analyzed by the use of engineering algorithms and linear finite elementmethod, and the results are compared. The shape of the doorway has an effect on thebuckling performance of the tower, which cannot be ignored; In the meantime, the use ofdoorframe at the doorway can significantly enhance the buckling strength of the bottom tower. For the tower subject to the cyclic loading, fatigue analysis of the tower undernormal operating conditions is carried out by MSC. Fatigue, the fatigue life is achieved andcompared with the life expectancy.