风力发电机组塔筒地震载荷计算

SEISMIC LOAD CALCULATION OF WIND TURBINE TOWER

建立3种不同精细程度的风力发电机组有限元模型,开展模态分析;采用振型分解反应谱法计算塔底地震载荷。结果表明:考虑叶片的柔性后,塔筒模态频率降低,塔底地震载荷总体上减小;考虑土-结构相互作用后,塔筒模态频率进一步降低,塔底地震载荷增大,这是因为塔底地震载荷同时受模态频率和模态振型的影响,模态振型的变化使模态参与因子增大,覆盖了模态频率对地震载荷减小的贡献;塔底地震载荷随地基刚度的变化呈无规律状态,当地基刚度取某个值时,塔底剪切力或弯矩会达到最大值,设计时应予以避免;叶片和土-结构相互作用对塔底地震载荷有重要影响,在建模和计算时应当考虑。

Three different sophisticated-level finite element models of wind turbine are established, and modal analysis is conducted. The seismic loads of tower bottom are calculated according to the mode-decomposition response spectrum method. The results showed that after considering the flexibility of blades, the modal frequencies of the tower decrease, and the seismic loads of the tower bottom decrease on the whole. After considering soil-structure interaction, the tower frequencies decrease further, but the bottom seismic loads increase, as the loads are influenced by the modal frequencies and shape together, the change of modal shape makes the modal participation factor increases, which covering the reduced contribution from modal frequencies. The seismic loads of the tower bottom change with the foundation stiffness irregularly. When the foundation stiffness takes a certain value, the bottom shear forces and bending moments will reach the maximum values, which should be avoided during design. The blade and soil-structure interaction are important for the modeling of wind turbine and should be considered when calculating the seismic load.