无损检测在风电叶片中的应用

风电叶片在生产与运输、安装的过程中会因操作不当而产生缺陷,这些缺陷不但会影响叶片的强度和刚度,而且在很大程度上会影响叶片的使用寿命,但是当前大多数的现场监测系统不能对其进行有效检测,使这些缺陷成为后期事故的隐患。文章从阐述缺陷产生的原因出发,对风电叶片的无损缺陷检测的主要方法进行了介绍,重点介绍了超声波检测和热成像检测的原理、方法、过程与注意事项,并进一步比较了两者在检测风电叶片领域的应用与优缺点。对指导风电叶片的无损检测、延长其使用寿命有一定的现实意义。

基于光纤光栅风电桨叶健康监测系统的研究

风电桨叶是风力发电系统中的关键部件,运行环境十分恶劣,长时间受极端天气的影响,隐患随时都有可能演变成事故,因此对风电桨叶进行结构健康监测势在必行。本论文根据风电桨叶监测的需求构建了模拟监测实验系统,进行了桨叶静态受力和动平衡实验测试,通过多通道高速光纤光栅解调仪和LabVIEW监控软件采集了大量原始测试数据,并对实验数据进行了细致的分析,在此基础上建立了桨叶健康监测的数值分析方法,为桨叶超限状态的判别和快速预警功能的实现打下良好的基础。

基于FBG风电桨叶动平衡监测系统的研究

风电桨叶是风力发电系统中的关键部件,风电场的事故多发生在盛风发电期,运行环境十分恶劣,长时间受恶劣天气的影响,随时都有可能对风机产生危害,因此对风电桨叶的结构进行健康监测迫在眉睫。本监测系统通过高速采集处理设备提供实时的风电叶轮的动平衡力学数据,能够测量出偏航、风切变、湍流等对风电叶片气动性能的影响程度,为调整风机运行状态提供技术参数支持。

Dynamic Characteristics Analysis of the Offshore Wind Turbine Blades

The topic of offshore wind energy is attracting more and more attention as the energy crisis heightens.The blades are the key components of offshore wind turbines,and their dynamic characteristics directly determine the effectiveness of offshore wind turbines.With different rotating speeds and blade length,the rotating blades generate various centrifugal stiffening effects.To directly analyze the centrifugal stiffening effect of blades,the Rayleigh energy method (REM) was used to derive the natural frequency equation of the blade,including the centrifugal stiffening effect and the axial force calculation formula.The axial force planes and the first to third order natural frequency planes which vary with the rotating speed and length were calculated in three-dimensional coordinates.The centrifugal stiffening coefficient was introduced to quantitatively study the relationship between the centrifugal stiffening degree and the rotating speed,and then the fundamental frequency correction formula was built based on the rotating speed and the blade length.The analysis results show that the calculation results of the fundamental frequency correction formula agree with the theoretical calculation results.The error of calculation results between them is less than 0.5%.

Monitoring of Wind Turbine Blades Based on Dual-Tree Complex Wavelet Transform

Structural health monitoring(SHM)in-service is very important for wind turbine system.Because the central wavelength of a fiber Bragg grating(FBG)sensor changes linearly with strain or temperature,FBG-based sensors are easily applied to structural tests.Therefore,the monitoring of wind turbine blades by FBG sensors is proposed.The method is experimentally proved to be feasible.Five FBG sensors were set along the blade length in order to measure distributed strain.However,environmental or measurement noise may cover the structural signals.Dual-tree complex wavelet transform(DT-CWT)is suggested to wipe off the noise.The experimental studies indicate that the tested strain fluctuate distinctly as one of the blades is broken.The rotation period is about 1 s at the given working condition.However,the period is about 0.3 s if all the wind blades are in good conditions.Therefore,strain monitoring by FBG sensors could predict damage of a wind turbine blade system.Moreover,the studies indicate that monitoring of one blade is adequate to diagnose the status of a wind generator.

Intelligent Wind Power Unit with Tandem Wind Rotors and Armatures （Optimization of Front Blade Profile）

The authors have invented the superior wind power unit, which is composed of the tandem wind rotors and the double rotational armature type generator without the traditional stator. The large-sized front wind rotor and the small-sized rear wind rotor drive, as for the upwind type, the inner and the outer rotational armatures, respectively, in keeping the rotational torque counter-balanced between both wind rotors/armatures. The unique rotational behaviors of the tandem wind rotors and the fundamental performances of the unit have been discussed at the previous paper. Continuously, this paper investigates experimentally and numerically the flow condition around the wind rotors to know the flow interactions between the front and the rear wind rotors, and optimizes the blade profile in the front wind rotor. The front blade should work fruitfully at the larger radius and had better not work at the smaller radius for giving plenty of wind energy to the rear wind rotor, taking account of the flow interaction between both wind rotors.

Analysis of Aerodynamic Load on Straight-bladed Vertical Axis Wind Turbine

This paper presents a wind tunnel experiment for the evaluation of energy performance and aerodynamic forces acting on a small straight-bladed vertical axis wind turbine(VAWT) depending on several values of tip speed ratio. In the present study, the wind turbine is a four-bladed VAWT. The test airfoil of blade is symmetry airfoil(NACA0021) with 32 pressure ports used for the pressure measurements on blade surface. Based on the pressure distributions which are acted on the surface of rotor blade measured during rotation by multiport pressure-scanner mounted on a hub, the power, tangential force, lift and drag coefficients which are obtained by pressure distribution are discussed as a function of azimuthally position. And then, the loads which are applied to the entire wind turbine are compared with the experiment data of pressure distribution. As a result, it is clarified that aerodynamic forces take maximum value when the blade is moving to upstream side, and become small and smooth at downstream side. The power and torque coefficients which are based on the pressure distribution are larger than that by torque meter.