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1.
The long composite blades on large wind turbines experience tremendous stresses while in operation. There is an interest in implementing structural health monitoring (SHM) systems inside wind turbine blades to alert maintenance teams of damage before serious component failure occurs. This paper proposes using an energy harvesting device inside the blade of a horizontal axis wind turbine to power a SHM system. The harvester is a linear induction energy harvester placed radially along the length of the blade. The rotation of the blade causes a magnet to slide along a tube as the blade axis changes relative to the direction of gravity. The magnet induces a voltage in a coil around the tube, and this voltage powers the SHM system. This paper begins by discussing motivation for this project. Next, a harvester model is developed, which encompasses the mechanics of the magnet, the interaction between the magnet and the coil, and the current in the electrical circuit. A free fall test verifies the electromechanical coupling model, and a rotating test examines the power output of a prototype harvester. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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The present work investigates the performance of different features, extracted from vibration-based data, for structural health monitoring of a 52-meter wind turbine blade during fatigue testing. An active vibration monitoring system was used during the test campaign, providing periodic excitation of single frequencies in the medium-frequency range, and using accelerometers to measure the vibration output on different parts of the blade. Based on previous work from the authors, data is available for the wind turbine blade in healthy state, with a manually induced damage, and with progressively increasing damage severity. Using the vibration data, different signal processing methods are used to extract damage-sensitive features. Time series methods and time-frequency domain methods are used to quantify the applied active vibration signal. Using outlier analysis, the health state of the blade is classified, and the classification accuracy through use of the different features is compared. Highest performance is generally obtained by auto-regressive modeling of the vibration outputs, using the auto-regressive parameters as features. Finally, suggestions for future improvements of the present method toward practical implementation are given. 相似文献
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Wind power is the world's fastest growing renewable energy source, but operations and maintenance costs are still a major obstacle toward reliability and widescale adoption of wind power, accounting for a large part of the cost of energy for offshore installations. Structural health monitoring systems have been proposed for implementing condition‐based maintenance. The wind energy industry currently uses condition monitoring systems that are mostly adapted from roating machinery in other power generation industries. However, these systems have had limited effectiveness on wind turbines because of their atypical operating conditions, which are characterized by low and variable rotational speed, rapidly varying torque, extremely large rotors and stochastic loading from the wind. Although existing systems primarily take measurements from the nacelle, valuable information can be extracted from the structural dynamic response of the rotor blades to mitigate potentially damaging loading conditions. One such condition is rotor imbalance, which not only reduces the aerodynamic efficiency of the turbine and therefore its power output but can also lead to very large increases in loading on the drivetrain, blades and tower. The National Renewable Energy Laboratory's fast software was used to model both mass and aerodynamic imbalance in a 5 MW offshore wind turbine. It is shown that a combination of blade and nacelle measurements, most of which can be obtained from standard instrumentation already found on utility‐scale wind turbines, can be formulated into an algorithm used to detect and locate imbalance. The method described herein allows for imbalance detection that is potentially more sensitive than existing on‐line systems, while taking advantage of sensors that are already in place on many utility‐scale wind turbines. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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In this paper, we consider the problem of reducing the radar cross section of a wind turbine blade through the application of radar absorbing material (RAM). One problem encountered by these techniques is the integration of the RAM solution with the existing lightning protection system, which is mandatory requirement to protect the blade when in operation. A common form of lightning protection is the use of conducting lightning receptors on the surface of the blade. To ensure the protection system is effective, a clearance area around the receptor may be required before any RAM treatment is applied. The size of the clearance area and the number of lightning receptors therefore potentially reduce the effectiveness of the RAM treatment. Design guidelines are given in this paper for a generic 40 m blade geometry. Some modelling results of the radar cross section and Doppler signature from a RAM treated blade are presented, and a comment is also made on the importance the blade edges have in reducing radar effects. ©2013 The Authors. Wind Energy published by John Wiley & Sons, Ltd. 相似文献
5.
A probabilistic stress analysis tool predicting reliability of composite wind turbine rotor blades was developed and validated by comparing with results from a three‐dimensional shell finite element model of a blade. Stress analysis was based on thin wall multicellular Euler–Bernoulli beam theory using as input section stress resultants directly from aeroelastic simulations; a finite strip method was implemented for elastic stability calculations. Reliability analysis was performed at the ply level of the multidirectional laminates implementing various methods such as the response surface method, β‐index and crude Monte Carlo simulation. Physical and statistical uncertainties of the basic variables was taken into account while several model uncertainties related to the material properties were further introduced and quantified in the light of appropriate test results. To prove the efficiency of the code as a design tool, the effect of various probabilistic assumptions concerning the material properties was directly investigated on the estimated reliability β‐index values for two rotor blade design cases typical of stall‐regulated and pitch‐regulated wind turbines. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
Structural health monitoring in the context of a Micon 65/13 horizontal axis wind turbine was described in this paper as a process in statistical pattern recognition. Simulation data from a calibrated model with less than 8% error in the first 14 natural frequencies of vibration was used to study the operational response under various wind states as well as the effects of three types of damage in the blade, low speed shaft and yaw joint. It was shown that vertical wind shear and turbulent winds lead to different modal contributions in the operational response of the turbine suggesting that the sensitivity of operational data to damage depends on the wind loads. It is also shown that there is less than a 4% change in the wind turbine natural frequencies given a 25% reduction in the stiffness at the root of one blade. The modal assurance criterion was used to analyse the corresponding changes in modal deflections, and this criterion exhibited nearly orthogonal changes because of the three damage scenarios suggesting that the modal deflection determines which damage is observable at a given frequency for a given wind state. The' modal contribution is calculated as a damage feature, which changes as much as 100% for 50% reductions in blade root stiffness, but only the blade damage is detected using this feature. Operational data was used to study variations in the forced blade response to determine the likelihood that small levels of damage can be detected amidst variations in wind speed across the rotor plane. The standard deviation in measured data was shown to be smallest for the span and edge‐wise measurements at 1P due to gravity, which provides the dominant forcing function at this frequency. A 3% change in the response in the span and edge‐wise directions because of damage is required to detect a change of three standard deviations in contrast to the 90% change in flap direction response that is required to detect a similar change because of damage. The dynamic displacement in the span direction is then used to extract a damage feature from the simulation data that provides the ability to both locate and quantify the reduction in stiffness in the blade root. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
7.
Peyman Poozesh Alessandro Sabato Aral Sarrafi Christopher Niezrecki Peter Avitabile Rahul Yarala 《风能》2020,23(7):1619-1639
Wind turbine blade certification requires static and fatigue testing at a large‐scale facility similar to the Wind Technology Testing Center (WTTC) located in Charlestown, Massachusetts. Usually, these tests are conducted by using wire‐based sensors such as strain gages, accelerometers, and string potentiometers. These systems are expensive, require a time‐consuming installation (e.g., up to 3 weeks and $35 k–$50 k for a strain gage system on a 55‐m‐long blade), are difficult to deploy on large‐sized structures, require additional instrumentations (e.g., power amplifiers and data acquisition systems), and produce results only at a handful of a discrete number of measurement points. In this study, a multicamera measurement system is implemented and experimentally evaluated to obtain full‐field displacement and strain over a ~12‐m‐long portion of a ~60‐m utility‐scale wind turbine blade. The proposed system has the potential to streamline the certification process by reducing the blade's preparation and sensor installation cost and time to a few hundreds of dollars (for painting equipment) and a few days for preparing the surface of the blade for the test. Furthermore, operational modal analysis was used in conjunction with the multicamera system to estimate the natural frequencies and mode shapes of the wind turbine blade. The obtained results have shown that the proposed approach can detect in‐plane displacement as low as 0.2 mm, mechanical strain with an error below 3% when compared with measurement performed using strain gages, and the first five natural frequencies with an error below 2% when compared with data recorded using traditional wire‐based accelerometers. This paper presents these results and provides a summary of the strengths and weaknesses of the proposed optical measurement approach in the context of streamlining the blade certification/testing process and performing vision‐based structural dynamic measurements on large‐scale structures. 相似文献
8.
A generalized computational methodology for reduced order acoustic‐structural coupled modeling of the aeroacoustics of a wind turbine blade is presented. This methodology is used to investigate the acoustic pressure distribution in and around airfoils to guide the development of a passive damage detection approach for structural health monitoring of wind turbine blades for the first time. The output of a k ? ε turbulence model computational fluid dynamics simulation is used to calculate simple acoustic sources on the basis of model tuning with published experimental data. The methodology is then applied to a computational case study of a 0.3048‐m chord NACA 0012 airfoil with two internal cavities, each with a microphone placed along the shear web. Five damage locations and four damage sizes are studied and compared with the healthy baseline case for three strategically selected acoustic frequencies: 1, 5, and 10 kHz. In 22 of the 36 cases in which the front cavity is damaged, the front cavity microphone measures an increase in sound pressure level (SPL) above 3 dB, while rear cavity damage only results in six out of 24 cases with a 3‐dB increase in the rear cavity. The 1‐ and 5‐kHz cases show a more consistent increase in SPL than the 10‐kHz case, illustrating the spectral dependency of the model. The case study shows how passive acoustic detection could be used to identify blade damage, while providing a template for application of the methodology to investigate the feasibility of passive detection for any specific turbine blade. 相似文献
9.
曾世龙;马强;白学宗;马辉东;安宗文 《太阳能学报》2024,45(3):41-45
为确定在役风电叶片到达设计寿命后能否延寿继续使用,提出一种基于恒幅寿命图模型的延寿区间计算方法。首先,分析叶片在运行工况下的载荷状况,采用应力-寿命（S-N）曲线分析弯矩作用下的疲劳寿命,进而定义弯矩-寿命（M-N）曲线。根据M-N曲线和CLD模型的映射关系建立延寿估计的CLD模型。基于延寿估计的CLD模型计算待退役叶片已累积的疲劳损伤,并从疲劳损伤估计可持续延寿的时间。最后,以某型叶片为例应用该方法进行延寿区间估计。 相似文献
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风力机叶片质量的急速增加已成为限制其大型化发展的主要因素之一。为减少叶片质量,论文借鉴植物叶脉分布特征提出一种新型仿生叶片。通过有限元方法建立具有仿生叶脉内肋结构并进行相应铺层设计获得轻量化叶片,基于流固耦合方法验证叶片在不同偏航角极端环境下的结构性能,结果表明：仿生叶片可在保证结构刚度、极限强度和稳定性方面性能与传统叶片相近的前提下减轻6.6%的重量;仿生叶片的内肋结构有助于增强叶片结构刚度,减小叶片叶尖形变量,且有助于降低叶片表面最大应力,但腹板最大应力略有增加;仿生叶片因除去尾缘加强材料导致偏航-15°极端风载荷下的抗屈曲性能略有降低,但总体仍在安全范围内。 相似文献
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Wind turbine blades often present complex distributions of their stiffness, mass and inertial properties along the span. We propose a method to estimate such physical parameters so as to match given experimental observations. The procedure can be used to understand the nature of possible discrepancies between designed and manufactured blades and to provide updated high fidelity mathematical beam models to be used in aero‐elastic simulations. The formulation is based on the constrained optimization of a maximum likelihood cost function and a noisy measurement fusion approach whereby the data of multiple experiments are used simultaneously in a single estimation process. The proposed method is demonstrated first using simulated data and then in the identification of two real small wind turbine blades. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
14.
以近海DTU 10 MW大型单桩式风力机为研究对象,利用Kaimal风谱模型与P-M谱分别建立湍流风场并定义波浪分布,基于绕射理论计算波浪载荷。选用东海某风电场土壤参数建立桩-土耦合效应模型,对比分析风浪载荷下基于不同桩-土耦合效应的风力机动力学响应、疲劳寿命及稳定性。结果表明：桩-土耦合效应对风浪载荷下风力机动力学响应起阻尼作用,将大幅降低其动力学响应,在抗风浪研究中,桩-土耦合效应不可忽略,否则将过度估计动力学响应;基于线性桩-土耦合效应与非线性桩-土耦合效应的风力机动力学响应、疲劳损伤及1阶屈曲因子相差较小,而较之于非线性桩-土耦合效应,风浪联合作用下多土层桩-土耦合效应风力机动力学响应略剧烈,疲劳寿命及1阶屈曲因子略小。 相似文献
15.
针对风电叶片主梁褶皱缺陷演化为初始损伤模式的不确定性问题,采用高斯概率分布函数确定7个因素的分布信息,根据褶皱缺陷在拉伸加载时的应力数据,改进Sobol'算法采用拉丁超立方法获取样本点训练BP神经网络,采用Kullback-Leibler散度计算最大和非最大损伤处的应变余能密度相对熵,分别作为基体开裂和纤维断裂的敏感度响应指标。结果表明,基体损伤和纤维断裂的高敏感因素均为载荷幅值、纤维含量、基纤模量比和褶皱高宽比,但基纤模量比与褶皱高宽比的排序有所不同,说明叶片主梁材料性能和缺陷特征形貌对初始损伤模式的作用程度不同。最后建立含褶皱的GFPR层合板有限元模型,模拟结果验证了全局敏感度分析方法的准确性。 相似文献
16.
D. Todd Griffith Nathanael C. Yoder Brian Resor Jonathan White Joshua Paquette 《风能》2014,17(11):1737-1751
Offshore wind turbines are an attractive source for clean and renewable energy for reasons including their proximity to population centers and higher capacity factors. One obstacle to the more widespread installation of offshore wind turbines in the USA, however, is that recent projections of offshore operations and maintenance costs vary from two to five times the land‐based costs. One way in which these costs could be reduced is through use of a structural health and prognostics management (SHPM) system as part of a condition‐based maintenance paradigm with smart loads management. This paper contributes to the development of such strategies by developing an initial roadmap for SHPM, with application to the blades. One of the key elements of the approach is a multiscale simulation approach developed to identify how the underlying physics of the system are affected by the presence of damage and how these changes manifest themselves in the operational response of a full turbine. A case study of a trailing edge disbond is analysed to demonstrate the multiscale sensitivity of damage approach and to show the potential life extension and increased energy capture that can be achieved using simple changes in the overall turbine control and loads management strategy. The integration of health monitoring information, economic considerations such as repair costs versus state of health, and a smart loads management methodology provides an initial roadmap for reducing operations and maintenance costs for offshore wind farms while increasing turbine availability and overall profit. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
17.
P. MalhotraR.W. Hyers J.F. ManwellJ.G. McGowan 《Renewable & Sustainable Energy Reviews》2012,16(1):284-292
Since the blades are one of the most critical components of a wind turbine, representative samples must be experimentally tested in order to ensure that the actual performance of the blades is consistent with their specifications. In particular, it must be demonstrated that the blade can withstand both the ultimate loads and the fatigue loads to which the blade is expected to be subjected during its design service life. In general, there are basically two types of blade testing: static testing and fatigue (or dynamic) testing. This paper includes a summary review of different utility-scale wind turbine blade testing methods and the initial design study of a novel concept for tri-axial testing of large wind turbine blades. This new design is based on a blade testing method that excites the blade in flap-wise and edgewise direction simultaneously. The flap motion of the blade is caused by a dual-axis blade resonance excitation system (BREX). Edgewise motion is delivered by the use of two inclined hydraulic actuators and linear guide rail system is used to move the inclined actuators in the flap-wise direction along the blade motion. The hydraulic system and linear guide rail requirements are analyzed and an initial cost estimate of the proposed system is presented. Recommendations for future work on this proposed system are given in the final section of this work. 相似文献
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P. K. Chaviaropoulos 《风能》1999,2(2):99-112
The scope of this article is to investigate the aeroelastic stability of wind turbine blade sections subjected to combined flap/lead–lag motion. The work is motivated by recent concern about destructive ‘edgewise' vibrations of modern, half‐megawatt‐scale, blades. The aeroelastic governing equations derive from the combination of a spring–mass–damper equivalent of the structure and a ‘non‐stationary' aerodynamic model. The aerodynamic model used in the present context is the differential dynamic stall model developed at ONERA. The resulting equations of motion are linearized and their stability characteristics are investigated in terms of the system entries, expressed through suitable, non‐dimensional, structural and aerodynamic parameters. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
20.
A computational model of rain erosion of wind turbine blades is presented. The model is based on the transient fluid–solid coupled finite element (FE) analysis of rain droplet/coating interaction and fatigue degradation analysis. The fatigue analysis of the surface degradation is based on multiaxial fatigue model and critical plane theory. The random rain fields are constructed computationally, and the estimated droplet sizes are included in FE model to acquire a library of load histories. Subsequently, the resulted nonproportional multiaxial high cycle fatigue problem is solved to assess the damage and lifetimes of the coatings. The approach can be used to design new coating systems withstanding longer service times. 相似文献