Estimation method of turbulent wind speed based on lidar pulse characteristics

Zibo, 庄子波 Zhuang; Xiaoyu, 刘晓宇 Liu; Xing, 陈星 Chen

doi:10.3788/irla201847.1106001

Cited by 2 publications

(1 citation statement)

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“…However, the wind speed measured in the nacelle is not suitable for control since the nacelle measurement is highly disturbed by the blades. In addition, extreme gusts can be accurately calculated by light detection and ranging (LIDAR) wind measurements [14][15][16][17][18]. However, wind speed varies with the site; thus, each wind turbine needs to be measured individually, and the extensive use of LIDAR will increase costs.…”

Section: Introductionmentioning

confidence: 99%

Study of Tower Clearance Safety Protection during Extreme Gust Based on Wind Turbine Monitoring Data

et al. 2022

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Large-scale wind turbines often face the problem of tower clearance safety under extreme gust conditions. Since gust intensity is positively correlated with the change rate of the generator’s speed, a gust identification method is proposed based on wind turbine monitoring data. Furthermore, a novel tower clearance safety protection strategy is proposed, which superimposes some additional speed requirements on the basis of normal pitch rate when identifying extreme gust so as to alleviate the dynamic response of the wind turbine. Simulations and comparison of a 5 MW wind turbine, before and after applying the new strategy, showed that the new strategy can induce an increase in pitch angle for the wind turbine and, simultaneously, avoids the emergency stop caused by the generator’s overspeed. Meanwhile, when the new strategy is adopted, the blade tip’s deformation and the load on the top of the tower are reduced by 19.9% and 52.2%, respectively. Therefore, the proposed strategy can not only protect the safety of the wind turbine but it also reduces costs.

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Section: Introductionmentioning

confidence: 99%

Study of Tower Clearance Safety Protection during Extreme Gust Based on Wind Turbine Monitoring Data

et al. 2022

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Effect of annealing temperature on structure and stress properties of Ta2O5/SiO2 multilayer reflective coatings

刘保剑¹,

段微波²,

李大琪³

et al. 2019

Acta Phys. Sin.

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In the optical system of spaceborne laser altimeter, dielectric mirror is an indispensable optical film element. Its surface shape quality directly affects the resolution and accuracy of distance measurement of the detection system. It is pressing and necessary to carry out research on the surface shape control technology of dielectric mirror to eliminate or reduce the effect of film stress on surface shape. The Ta2O5/SiO2 multilayer reflective coatings are deposited on quartz substrates by using the ion beam assisted electron beam evaporation (IBE), and then annealed in air in a temperature range from 200 to 600 ℃. The effect of annealing temperature on the structure, optical and stress properties of Ta2O5/SiO2 multilayer reflective coatings are systemically investigated by using x-ray diffraction, atomic force microscope, spectrophotometer and laser interferometer. The results show that all the Ta2O5/SiO2 multilayer reflective coatings, after being annealed, are amorphous in structure. The annealing temperature has a great influence on the surface roughness of reflective coating. With the increase of annealing temperature, the surface roughness of reflective coating first decreases and then gradually increases, but is still smaller than that of as-deposited sample. After being annealed, the reflectance spectrum of reflective coating shifts slightly toward the long-wave direction, and the reflectivity increases a little. When being annealed at 500－600 ℃, the compressive stress of reflective coating could be transformed into tensile stress, and the surface is changed from convex to concave shape. It can be concluded that annealing at an appropriate temperature can effectively release residual stress of Ta2O5/SiO2 multilayer reflective coating and eliminate the deformation of substrate caused by film stress, and thus improving the surface shape quality of dielectric mirror., After being annealed, the reflective coating still possesses the stable structure and spectral properties, so that dielectric mirror can meet the application requirements of spaceborne laser altimeter. In this paper, the experimental results are of great significance for applying the annealing technology to the surface shape control technology of dielectric mirrors.

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Estimation method of turbulent wind speed based on lidar pulse characteristics

Cited by 2 publications

References 0 publications

Study of Tower Clearance Safety Protection during Extreme Gust Based on Wind Turbine Monitoring Data

Study of Tower Clearance Safety Protection during Extreme Gust Based on Wind Turbine Monitoring Data

Effect of annealing temperature on structure and stress properties of Ta<sub>2</sub>O<sub>5</sub>/SiO<sub>2</sub> multilayer reflective coatings

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