Seismic assessment of wind turbines: How crucial is rotor-nacelle-assembly numerical modeling?
Seismic assessment of wind turbines: How crucial is rotor-nacelle-assembly numerical modeling?
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DOI：
10.1016/j.soildyn.2020.106483
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发表时间：
2020-10
影响因子：
4
通讯作者：
Ahmer Ali;R. Risi;A. Sextos
中科院分区：
文献类型：
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作者：
Ahmer Ali;R. Risi;A. Sextos
典型风力机叶片的横截面和结构扭角沿其跨度变化。这使得在对风力发电机进行非线性动力分析时，对其进行真实建模变得复杂。因此，集总质量方法是最常用来模拟转子-机舱装配（RNA）。RNA对塔顶偏心，叶片倾向于在塔顶上引起旋转惯性。排除这种旋转惯量和转子偏心可以影响风力涡轮机的结构响应，因为RNA对系统的总质量有很大的贡献。此外，叶片是细长的结构部件，可以在地震激励下独立振动和变形。集中质量方法本质上考虑了RNA的刚体惯性，它不可避免地作为塔顶的一部分。这可能会对海上风力发电机的地震易损性估计产生一定程度的影响，但目前还没有得到适当的量化。为了探讨这一问题，本研究讨论了三个关键RNA参数，即(i)叶片转动惯量，（ii）转子偏心，（iii）叶片柔韧性对浅层地壳地震下OWT地震破坏和易损性的影响。结果表明，旋转惯量影响高阶模态，进而影响塔的破坏区高度。研究还表明，不同水平的RNA建模细化会影响预测的失效概率，特别是在脉冲状地面运动下，而如果使用传统的刚体集总质量旋转惯性，则相同的估计会被高估。更糟糕的是，与柔性涡轮叶片的精细建模相比，当旋转惯性完全被忽略时，它们可能被低估（因此不太安全）。这些结果很有启发性，因为它们强调了地震危险确实会给某些地区的wot带来重大的设计问题。
The cross-section and the structural twist angle of a typical wind turbine blade vary along its span. This complicates its realistic modeling in nonlinear dynamic analysis of wind turbines when seismic performance estimates are sought. As a result, the lumped mass approach is most commonly used to model the rotor-nacelle-assembly (RNA). The RNA is eccentric to the tower top, and the blades tend to induce rotary inertia on the tower. The exclusion of this rotary inertia and the rotor eccentricity can impact the structural response of the wind turbines as the RNA contributes significantly to the total mass of the system. Moreover, the blades are long, slender structural components that can vibrate and deform independently under seismic excitation. The lumped mass approach intrinsically considers the rigid-body inertia for the RNA, which inevitably acts as a part of the tower top. This can affect the seismic vulnerability estimation of the offshore wind turbines (OWT) at a degree that has not yet been properly quantified. To explore this issue, the present study discusses the effects of the three key RNA parameters, i.e., (i) rotary inertia of the blades, (ii) rotor eccentricity, and (iii) blades’ flexibility, on the seismic failure and fragility of OWT under shallow crustal earthquakes. Results show that the rotary inertia affects the higher modes, which in turn influence the height of the tower failure zones. It is also shown that different levels of RNA modeling refinement affect the predicted failure probabilities, particularly under pulse-like ground motions, while the same estimates are overestimated if the conventional rigid body lumped mass rotary inertia is used. Even worse, they can be underestimated (thus less safe) when the rotary inertia is completely ignored, compared with the refined modeling of flexible turbine blades. These results are revealing as they highlight that seismic hazard can indeed pose a significant design issue for OWTs in some regions.