基于环境等值线法的海上浮式风机长期极限响应预测

Prediction of long-term extreme response of offshore floating wind turbine based on environmental contour method

为保证海上浮式风机在复杂的风浪环境载荷作用下正常服役,需要评估海上浮式风机的长期极限响应。通过实测风浪的联合概率分布,利用基于逆一次可靠度法(IFORM)和逆二次可靠度法(ISORM)的环境等值线法获取环境工况组合,模拟风机短期响应并结合Gumbel极值分布计算风机长期极限响应,实现了对海上浮式风机50 a重现周期的极限响应预测。研究结果表明:风浪联合作用下,随着平均风速增大,平台纵荡运动、叶根面外弯矩和塔基前后弯矩出现了先增大后减少的趋势;随着有义波高增大,平台纵荡运动最大值和平均值、塔基前后弯矩最大值也随之增大;与基于IFORM的环境等值线法相比,基于ISORM的环境等值线法可以涵盖更多的环境工况组合,得到更大的浮式风机长期极限响应,进一步提高了风机结构设计安全性。

To ensure the normal service of offshore floating wind turbine under complex environmental loads,such as wind and wave,it is necessary to evaluate the long-term extreme response of offshore floating wind turbine.Through the joint probability distribution of measured wind and wave,the combination of environmental conditions is obtained by the environmental contour methods based on the IFORM and the ISORM,and the short-term response is obtained by simulations.Combined with the Gumbel extreme value,the long-term extreme response of the wind turbine is calculated,and the extreme response analysis of the 50-year return period of the offshore floating wind turbine is realized.The results show that under the combined effect of wind and wave,with the increase of the mean wind speed,platform surge motion,bladed root out-of-plane bending moment,and tower base fore-aft bending moment first increase and then decrease;as the significant wave height increases,the maximum and mean values of platform surge motion and the maximum value of tower base fore-aft bending moment also increase.Compared with the environmental contour method based on IFORM,the environmental contour method based on ISORM can cover more combinations of environmental conditions and obtain greater long-term extreme response,which improves the safety of the wind turbine structure design.