Study On Dynamic Response Analysis And Monitoring Method Of Wind Turbine Tower In Mountainous Turbulent Wind Field

In recent years,the installed capacity of wind turbines in China has been increasing,and the height of the tower has also increased,and due to the complex working environment of wind turbines in mountainous environment,the tower is very prone to damage.Therefore,it is important to carry out research on the structural dynamic characteristics of the tower and improve the monitoring methods to ensure the safe operation of wind turbines.In this paper,we take 2 MW wind turbine tower as the research object,establish a mountain turbulent wind field in line with the actual working environment,analyze the dynamic response of the tower,and improve the tower monitoring method.The main research contents and conclusions of the paper are as follows.(1)The effects of wind shear,tower shadow and mountain environment on the mean wind speed are considered,and a non-stationary wind field with spatial three-dimensional and wind direction dependence is established by a turbulent coherent model based on Kaimal self-power spectrum and mutual power spectrum of longitudinal and vertical pulsating wind speed components using harmonic superposition method.A wind farm 2WM wind turbine is selected as an example for example analysis to validate the simulation method and compare it with that without considering the wind direction correlation.It is shown that the simulated power spectrum obtained is in good agreement with the target spectrum,which indicates that considering the wind direction correlation can improve the simulation agreement,thus proving the accuracy and necessity of the simulation method to realize the simulation of three-dimensional non-smooth pulsating wind field.(2)The dynamics model of impeller-nacelle-tower coupling is established by using ANSYS,and the inherent frequency and modal vibration pattern of the tower are obtained by modal analysis.The inherent frequency of the first section is similar to the result calculated by Rayleigh method,which verifies the reasonableness of the model;meanwhile,the self-oscillation frequency of the tower is calculated according to the standard outside the range of 10%of the rotation frequency of the impeller and the passing frequency of the blade,which can avoid the problem of additional load generated by resonance.(3)Based on the leaf element momentum theory to analyze the type of load on the tower,the change of wind direction is considered by changing the angle between the impeller orientation and the doorway orientation,the time course analysis of wind vibration response under normal operation wind condition and extreme load wind condition with different wind angle is carried out to study the influence law of wind speed and wind direction change on the displacement response and stress response of the tower,and the characteristic values of displacement response under different tower heights in mountain environment and flat environment are compared to illustrate the importance of the mountain wind field factor,and the time course analysis under the same wind load is carried out by the measured data to verify the applicability of the analysis results.(4)By calculating the vibration response of the damage model under the same wind condition,the tower vibration displacement curve is fitted,and by calculating the curve curvature,it is found that the single displacement index does not reflect the real state of the tower well.Therefore,the vibration monitoring index of the tower must be improved,and an improved monitoring method to calculate the curvature of the tower vibration displacement curve is proposed,and the feasibility of using the curvature as the monitoring index is verified.