风力发电机旋转样本谱及疲劳寿命预测

Rotationally sampled spectrum and fatigue life prediction of wind turbine system

为了考虑桨叶旋转效应,准确进行风力发电机疲劳寿命预测,提出了基于旋转样本谱的风力发电机疲劳寿命预测模型.借助Fourier变换,推导了考虑旋转效应的旋转样本谱,并与Von Karman谱(一种固定点紊流风谱)进行比较.在旋转样本谱的基础上,提出了源于Palmgren-Miner线性损伤准则的风力发电机疲劳寿命预测模型,并以1.25MW风力发电机为例进行疲劳寿命分析.结果表明,与固定点紊流风谱相比,旋转样本谱的能量分布发生了根本变化,其能量由低频向高频移动,在高频段曲线会出现多峰情况;基于旋转样本谱的疲劳寿命分析更接近实际情况,而基于Von Karman谱进行风力发电机疲劳寿命预测不够精确,且偏于不安全.

In order to take the rotating effect into consideration and predict the fatigue life of wind turbine system exactly,a fatigue life prediction model based on the rotationally sampled spectrum is proposed in this paper.Firstly,the rotationally sampled spectrum taking the rotating effect into consideration is deduced through the Fourier transformation and compared with the Von Karman spectrum（fixed point spectrum）.Based on the rotationally sampled spectrum,a fatigue life prediction model which derives from the Palmgren-Miner（P-M） linear damage model is provided.Then the fatigue life analysis of a 1.25 MW wind turbine system is carried out.The results show that the energy of the rotationally sampled spectrum transforms significantly from the low frequency region to the high frequency region.Besides,multi-peaks also appear in the high frequency region because of the energy shift.The fatigue life prediction model based on the rotationally sampled spectrum can predict the fatigue life and evaluate the security of the wind turbine structure more exactly compared with the one based on the Von Karman spectrum,which will overestimate the fatigue life and is unsafe for the fatigue life prediction of wind turbines.