The Deflection Law Of Wind Turbine Foundation Under The Influence Of Initial Deviation And Its Monitoring Method

As the main load-bearing member,the wind turbine foundation may be damaged gradually under complex loading and environmental effects.A lot of research work has been carried out by domestic and foreign scholars on the damage to wind turbine foundations and monitoring methods,but the influence of initial deviation is often neglected in the analysis of wind turbine foundation damage mechanisms.Due to the influence of initial deviation,the maximum damage to the fan foundation may not be in the main wind direction.In this paper,the finite element method is used to analyze the influence law of initial deviation on the offset of fan foundation,and a method of online monitoring of the maximum offset of fan foundation is designed,which has important theoretical significance and engineering application value for the safe operation and management of the fan.The main research and findings of this paper are as follows:(1)analyzed the factors affecting fan foundation damage,and defined uneven settlement of fan foundation and foundation ring installation error as the initial deviation of fan foundation.To investigate the mechanism of the initial deviation on the wind turbine foundation,and to analyze the influence of the initial deviation direction and the initial deviation size on the maximum displacement of the wind turbine foundation by the control variable method,so as to provide a theoretical basis for the load application in the finite element analysis.(2)A combined modeling approach was selected to establish the ANSYS finite element model of the wind turbine foundation,using Targe 170 cells and Contal173 cells to simulate the contact behavior between the concrete and foundation ring of the wind turbine foundation and between the concrete and the foundation.Set friction coefficients of 0.3 versus 0.65,respectively.Fine delineation of the base ring using a mapping grid.The foundation soil boundary is taken as three times the diameter and height of the foundation.(3)Taking a 1.5 MW wind turbine foundation as an example,analyze the influence law of initial deviation on the offset of the wind turbine foundation:When the angle θ between the initial deviation direction and the main wind direction remains unchanged,the angle βbetween the direction of the maximum displacement of the foundation and the main wind direction increases with the increase of the initial deviation α.When the initial deviation α is constant,the angle β between the direction of the maximum displacement and the main wind direction increases first with the increase of θ.β is maximum when θ reaches 90°,and then starts to decrease.β=0 when θ is 0° and 180°,i.e.the maximum displacement of the fan foundation occurs in the main wind direction.Based on the initial deviation a and the angle βbetween the initial deviation and the direction of the main wind,the direction in which the maximum deviation of the wind turbine foundation occurs can be predicted.(4)A method of online monitoring of the maximum offset of the foundation of a wind turbine was designed to install the equipment to the corresponding position of the flange on the foundation ring according to the law of offset of the foundation of the wind turbine.Propose to set the tilt monitoring limit as δ=δ1+δ2+δ3=δ1+δ2+0.15°,which can objectively reflect the degree of foundation deflection.The test and field application show that the monitoring method can achieve real-time capture of the maximum offset of the foundation,providing an effective monitoring method for the health monitoring of wind turbine foundations in actual engineering.