考虑不同边界约束条件下的风电机塔架固有频率分析  

Finite Element Analysis of the Natural Frequency for a Wind Turbine Tower Under Different Boundary Constraints

作　　者：王佼姣[1] 施刚[1] 石永久[1] 王元清[1] 

机构地区：[1]土木工程安全与耐久教育部重点实验室清华大学土木工程系,北京100084

出　　处：《特种结构》2011年第5期5-8,108,共5页Special Structures

摘　　要：为了准确分析地基土刚度和基础本身刚度对风力发电机塔架动力特性的影响,利用大型通用有限元软件ANSYS对某风力发电机塔架分别建立塔筒有限元模型和塔筒及基础的整体有限元模型,对塔架进行模态分析:考虑不同的边界约束条件,包括塔筒底部刚接、混凝土基础底部刚接、基础底部和侧面均刚接、基础底部刚接侧面约束两个水平方向、基础底部加扭转和竖向弹簧、基础底部加扭转和竖向弹簧并且侧面加水平向弹簧几种模型,确定其固有频率和振型。有限元模型中,机舱质量和叶轮质量以质量单元方式加于塔筒顶部。不同约束条件下的固有频率计算结果显示,地基和基础的弹性对整体结构固有频率有一定影响,是否考虑地基土刚度和基础本身刚度的计算结果的差别为11.6%。这表明在设计中,宜考虑基础本身刚度和地基土刚度对风电机塔架动力性能的影响。最后将塔架固有频率与叶片转动频率1p(1个叶片)、3p(3个叶片)进行比较,结果显示塔架固有频率与1p上限值非常接近,对塔架系统动力特性较为不利。In order to analyze the influence of ground and foundation stiffness on dynamic characteristics of wind turbine,modal analysis was carried out by ANSYS software.The finite element models of the steel tower with and without the concrete foundation were both established.Natural frequency and natural mode of vibration were determined under different boundary constraints including bottom of steel tower fixed,bottom of concrete foundation fixed,bottom and side end of foundation fixed,bottom of foundation fixed and displacement of two horizontal directions of side end of foundation constrained,rotational spring and vertical compression - tension spring set at the bottom of foundation, rotational spring and vertical compression - tension spring set at the bottom of foundation and horizontal compression - tension spring set at the side end of foundation.In the finite element modal,mass element of machinery space and blade was established on top of the tower.Calculating results under different boundary constraints showed that flexibility of foundation and ground had a certain effect on natural frequency of the whole structure.Difference between frequency results of stiffness of foundation and ground considered or not was about 11.6%.This indicated that stiffness of foundation and ground could not be neglected in the design.The author compared the natural frequency of the tower and 1p,3p of the blade rotation frequency.The little gap between the natural frequency and upper limit value of 1p showed the unfavorable dynamic properties of the tower.

关 键 词：风电机塔架 模态分析 固有频率 约束条件 有限元分析 

分 类 号：TM315[电气工程—电机]