基于实测数据的海上风电结构动力响应分析

地震是危害海上风电结构作业安全的重要环境因素，目前，国内尚未公开发表真实地震响应下，海上风电结构的实测动力响应数据。分析了某地震活动区海上风电结构的实测地震响应，采用随机子空间识别方法进行风机的模态识别，阐述了风机机舱偏航将引起前后、左右两个正交方向振动的耦合，并从理论上证明了利用耦合、解耦数据识别模态参数的差异。结果表明：1）耦合与解耦信号识别的频率、阻尼比完全相同，而耦合信号识别的模态振型与偏航角有关；2）地震作用会对结构产生巨大冲击；3）非地震作用下，风机塔筒前后、左右第一阶弯曲模态为主要模态，地震作用可以激发风机的高阶模态，使得塔筒中上部而不是顶部的振动响应最大。此分析对地震活动区海上风电结构的抗震设计具有一定的参考价值。

Analyzing the dynamic response of an offshore wind turbine with field test data

Earthquake is one of the major natural factors threatening the safety of offshore wind turbines (OWTs). Nevertheless, the field test data analysis on OWTs under earthquake excitations has not yet been published within China. This paper analyzes the dynamic responses of a real OWT located in a seismically active area. The SSI method is used to identify the modal parameters of the OWT. It is claimed that the FA and SS signals collected by the sensors are coupled due to the yaw motion of the nacelle and the relationship between the modal parameters estimated with the coupled and decoupled signals is theoretically proved. The results show that the natural frequencies and damping ratios identified are the same before and after a yaw motion while the mode shapes are possibly different; the earthquake has a dramatic impact on the structure; and the first FA and SS bending modes contribute mostly to the vibration of the OWT without earthquake excitations. However, the earthquake excited some high-frequency modes. As a result, the upper rather than the top of the tower had the largest vibration. The dynamic response analysis is conducive to the seismic design of OWTs.