低风速型风电机组高柔塔筒涡激振动疲劳损伤评估

FATIGUE DAMAGE ASSESSMENT FOR VORTEX INDUCED VIBRATION OF HIGH-SOFT TOWER OF LOW WIND SPEED WIND TURBINE

为实现低风速型风电机组高柔塔筒抗疲劳设计,以某140 m柔塔机组为研究对象,采用欧盟标准EN 1991-1-4推荐的有效相关长度法和频谱模型法,开展涡激振动疲劳损伤评估。基于有限元法建模获取结构固有模态属性;由疲劳应力-寿命(S-N)曲线、风速瑞利分布和Miner法则推导塔筒疲劳应力范围和损伤规则;对比分析柔塔与刚塔两类机型临界风速分布和焊缝疲劳损伤分布。结果表明:柔塔更易激发二阶涡激振动,二阶涡激载荷显著增大,其损伤对不同风场条件(年平均风速、风切变)极为敏感;在6.5 m/s设计风速下,45%~85%塔筒高度处疲劳损伤均超过IEC 61400-6塔架与基础设计要求20年损伤限值0.1,存在疲劳破坏风险,须考虑加阻措施或优化结构设计。

In order to reach the anti-fatigue design of high-soft tower of low wind speed wind turbine,taking a 140 m soft tower as the research object,the vortex induced vibration fatigue damage assessment uses the effective correlation length method and spectrum model method recommended by EU standard EN1991-1-4.Acquire inherent modal attributes of the structure by modeling based on finite element method;Derive the fatigue stress range and damage rule of tower from S-N curve,Rayleigh distribution of wind speed and Miner rule;The critical wind speed distribution and weld fatigue damage distribution of soft tower and rigid tower are compared and analyzed.The results show that the soft tower is easier to excite the second-order vortex induced vibration,the second-order vortex induced load increases significantly,and its damage is extremely sensitive to different wind field conditions(annual average wind speed and wind shear);Under the design wind speed of 6.5 m/s,the fatigue damage at 45%-85%of the tower height exceeds the 20-year damage limit of IEC 61400-6 requirement for tower and foundation design by 0.1.There is a risk of fatigue damage,so it is necessary to consider the resistance adding measures or optimize the structural design.