In the light of the geometric characteristics of wind turbine and the distribution of stiffeners, the finite element models for the megawatt horizontal axis wind turbine are established by ANSYS. A model analysis is made of the effect of the foundation stiffness, longitudinal stiffeners, ring stiffeners and orthogonal stiffeners on natural frequency and vibration mode of the tower. The results show that the foundation stiffness and stiffeners all have a certain influence on the natural frequency of the tower. There is a 7% difference in the first-order natural frequency between the models of the tower with and without foundation stiffness; there is an increase in natural frequency of the tower when longitudinal stiffeners or orthogonal stiffeners are considered, while natural frequency of the tower experiences an erratic change with the increase of ring stiffeners. The present study will provide some theoretical basis for the optimization design of wind turbines.

Based on a kind of 1.5MW large-scale horizontal axis wind turbine tower, the mechanical modeling of a wind turbine tower-foundation is established, the static and dynamic analysis of the model is carried out by ANSYS software. The top displacement of the system is calculated by the static analysis to meet the design requirements in engineering. In dynamic analysis, each pile foundation is equivalent to a group of springs for the simulation of horizontal and vertical rigidity of the pile. The influence of top mass and foundation elasticity on wind turbine tower modes is analyzed, and calculated the natural frequency of the tower within a certain scope of rigidity in different directions about the piles foundation. The results show that the natural frequency of the wind turbine tower is influenced significantly by the mass on the tower top and foundation rigidity. The study provides a theoretical basis for optimal design of the wind turbine.