什么是风速？

风的大小常用风的速度来衡量，风速是单位时间内空气在水平方向上所移动的距离。专门测量风速的仪器，有旋转式风速计、散热式风速计和声学风速计等。风速的单位常以m／s，km／h，mile／h等来表示。     

基于邻比模型分析的风电机组传感器监测研究

以风速计为例,提出基于邻比模型的风电机组传感器监测方法。风资源相似的多台风电机组(邻比机组)的运行工况和传感器测量值存在较强的相关相似性。采用多台风电机组风速计正常测量数据和非线性状态估计方法来建立多个风速计横向之间的邻比模型,该模型反映了邻比机组风速之间的相关相似关系。模型建立后,将风速计实时测量风速作为模型的输入。当某台机组的风速计出现测量异常时,其与其他邻比机组风速计之间原有的相关相似关系被破坏,邻比模型对该机组风速的预测残差将会显著增大,预示该风速计出现故障。该方法能够实现风电机组传感器状态的实时监测。通过某风电场实际运行数据,验证了该方法的有效性。     

风力机风速仪安放位置对测量风速的准确度研究

为了提供风力机风速仪测量风速的准确性,本文采用CFD方法对风速仪在不同安放位置下测量风速的准确性进行数值研究,结果表明:竖直高度上,监测风速位置接近或远离机舱均使监测风速与来流风速存在较大偏差;水平距离上,机舱两侧监测位置上的风速较高,波动小,向机舱中心越靠近,风速减小,波动增加;同时,通过在额定风速下寻优得到风速仪最佳测风位置,可减小其它来流下风速仪测量风速的偏差。     

基于湍流的双NTF方法应用于机舱风速计测量功率曲线

机舱风速计测量功率曲线的误差较大,造成风电功率预测结果的不确定性。文章依托某风电场现场实验,研究了机舱风速-自由流风速的关系,探讨了大气湍流强度对机舱传递函数(NTF)的影响,提出了基于湍流的双NTF方法,并应用于机舱风速计测量功率曲线。在不同年平均风速情况下,采用未修正的机舱风速功率曲线、国际电工委员会(IEC)提出的单NTF方法修正后的机舱风速功率曲线和文章所提出的双NTF方法修正后的机舱风速功率曲线,分别评估年发电量,其误差范围分别为-8.8%~-0.5%,-2.4%~-0.2%和-0.2%~0.2%。研究结果表明,文章所提出的基于湍流的双NTF方法是可行的,其应用效果优于IEC提出的单NTF方法。     

滨州市市区典型路口粉尘分布特征分析

通过监测夏季滨州市4个典型路口的粉尘浓度,分析夏季滨州市典型路口粉尘分布与风速、高度、湿度之间的关系。研究结果表明随着车流量的变化,粉尘浓度呈不同态势分布,车流量越大时,粉尘浓度越高;车流量一定时,风速与粉尘浓度成正的偏相关性,即风速越大,粉尘浓度相应增大;车流量一定时,高度与粉尘浓度成负的偏相关性,即在同一地点随着高度的升高,粉尘浓度降低;空气湿度较大时,高度对粉尘浓度大小的影响比空气湿度对粉尘浓度大小的影响要小。     

太阳能光伏组件表面沙尘沉降规律研究

运用Fluent中混合模型对沙粒在光伏组件表面的沉降行为进行模拟计算。分析了不同的风速以及安装倾角时,光伏组件表面沉降规律的变化情况。研究结果表明:风速越大、安装倾角越大,沙尘在组件表面的沉降分层明显;通过公式计算组件表面的沉降量,知道风速不变时,安装倾角的角度越大,沙尘在组件表面的沉降量也越大;安装倾角不变时,当风速越大,沙尘的沉降量却越小,说明安装倾角以及风速是影响光伏组件表面沙尘沉降的两个重要因素。     

风冷冷水机组V型冷凝器空气流动的模拟

建立了风冷热泵翅片管换热器空气侧流动与传热的数学模型,模拟了V型风冷翅片管换热器在不同翅片管间夹角与底部距离下的空气流场,分析了不同翅片管间夹角与底部距离对空气流动的影响。模拟结果表明,两换热面的夹角增大时,换热面的迎面风速和平均风速也随之增大,且增长相当明显,但最大风速相差不大。当底部间距增大时,换热面的迎面风速和平均风速亦随之增大,但变化的幅度比较小。     

小型风力机的选址与安装

一、风况与场址选择 1.风速的测定与风力机额定风速的选择风力机场址的选择对风能利用是很重要的,场址的选定取决于当地的平均风速。测定风速常用风速计,在预定安装风力机场址50米以内的范围内,离地面5～10米左右处进行测量。测量方式分为测瞬时风速、小时平均风速、日平均风速、月、季和年平均风速。风速随着离地面的高低而增减。因而测定风速时     

风速传感器对温度传感器测量影响的数值模拟及分析

为了提高焓差试验室干湿球温度测量的准确度,通过数值模拟分别研究了焓差室空气取样器中风速传感器探头直径的大小及其与干湿球温度传感器探头的相对位置对干湿球温度测量的影响。分析得出,直径更小的风速传感器对干湿球温度的测量结果影响更小;当风速传感器直径为8 mm,且风速传感器与干球温度传感器的水平距离达到100 mm时,风速传感器对干湿球温度的测量影响可忽略不计。研究结果可为焓差室空气取样器内传感器的布局提供参考与指导。     

基于Simon-wong刚体算法的风力机风速仪测风准确性研究

为了对风力机风速仪测量风速的准确性进行分析,本文以风速仪修正试验数据为基础,采用三维流场计算方法对其进行研究,并在数值研究中,加入风速仪计算模型,同时采用Simon-wong刚体算法解决风速仪在数值模拟中的被动响应问题。通过对试验数据和模拟结果对比分析后可知:风力机在运行状态下,风速仪测量风速与实际来流之间存在偏差,且最大偏差出现在风力机额定转速附近;与一般定常计算模拟相比,加入风速仪计算模型后,风速仪模拟测量风速最大误差由6.4%降为2.89%,模拟结果更为准确;风速仪在风速测量中,自身也存在测量风速极差,且极差随着来流风速的增加而变大。     

Detection of nacelle anemometer faults in a wind farm minimizing the uncertainty

The performance assessment of wind farms requires the acquisition of accurate power and wind speed data of each turbine. Nowadays, the nacelle anemometry is widely studied as an option for power performance verification. Therefore, systems to detect the nacelle anemometer faults in a wind farm in operation are necessary for maintenance purposes. In this paper, we propose a method to detect wind speed deviations of the nacelle anemometers by comparing them with the nearby anemometers. This comparison is made through an approach to estimate the wind speed in each nacelle. The approach is based on the discretization of wind speed data using the bin method. The key issue of this proposal is the estimation of the anemometer deviations considering the range of data with lower uncertainty. To this end, an average uncertainty model per bin and direction sector has been integrated into the method. The tests show that using wind speeds higher than 4.5 m s ^{? 1} gives the lowest uncertainty. Data from two wind farms have been used to test this method, and the obtained results have allowed the detection of problematic anemometers. Copyright © 2012 John Wiley & Sons, Ltd.     

基于风速时空关联的多步预测方法

基于风速的空间关联性提出一种新的多位置多步风速组合预测方法.对风场内各风力机进行灰色关联分析,并据此利用昆虫优化算法进行优选重构,获取目标风力机及临近域空间信息.利用卷积神经网络对重构矩阵进行空间特征提取,并输入长短时记忆网络进行多步预测.最后,将所提方法应用于不同风场进行风速预测,通过对比分析验证所提方法的预测精度和...     

On wind turbine power performance measurements at inclined airflow

The average airflow inclination in complex terrain may be substantial. The airflow inclination affects wind turbine performance and also affects the cup anemometer being used in power performance measurements. In this article the overall dependence of the power curve on inclined airflow is analysed for its influence on both the wind turbine and the cup anemometer. The wind turbine performance analysis is based on results of measurements and theoretical calculations with the aeroelastic code HAWC coupled to a 3D actuator disc model for varying yaw angle. The cup anemometer analysis at inclined flow is based on an averaging of measured angular characteristics in a wind tunnel with the distribution of airflow inclination angles over time. The relative difference in annual energy production in terrain with inclined airflow compared with flat terrain is simulated for cup anemometers with theoretical optimal angular characteristics for two different definitions of wind speed, as well as for five commercial cup anemometers with measured angular characteristics. Copyright © 2004 John Wiley & Sons, Ltd.     

Verification of theoretically computed spectra for a point rotating in a vertical plane

The ability to generate a model tubulent wind as it is seen by a rotating blade, independent of measurement, is important in wind turbine design and testing. A theoretical model of the spectrum of rotationally sampled wind speed developed at the Pacific Northwest Laboratory is tested against corresponding measured wind spectra. The measured spectra were selected from a number of cases measured with a vertical plane array of anemometers. The array was set up to correspond to the tip circle of a nearby MOD-OA wind turbine rotor blade. For purposes of testing and of illuminating the process, the turbulence and mean wind shear were treated separately. In each case the test was based on two criteria, each involving comparison of results from the theoretical model and results from real data analysis. These criteria were the rotational spectra and the integration of the spectra within each harmonic band into energy. Particularly the latter criterion was used. The measured spectra were selected to represent different atmospheric stability conditions. The theory is shown to achieve respectable accuracy readily except when applied to the stable atmosphere case. Recommendations are made for selection of the values of atmospheric parameters to be used for computing the theoretical result. The importance of the length of time of a measured turbulence record that is to be used in estimating several parameters for input to the theoretical model applied to real wind conditions at a selected turbine site is discussed. The VAX 11/780 computer time required to generate a model spectrum is usually less than one minute.     

Accounting for the speed shear in wind turbine power performance measurement

The current IEC standard for wind turbine power performance measurement only requires measurement of the wind speed at hub height assuming this wind speed to be representative for the whole rotor swept area. However, the power output of a wind turbine depends on the kinetic energy flux, which itself depends on the wind speed profile, especially for large turbines. Therefore, it is important to characterize the wind profile in front of the turbine, and this should be preferably achieved by measuring the wind speed over the vertical range between lower and higher rotor tips. In this paper, we describe an experiment in which wind speed profiles were measured in front of a multimegawatt turbine using a ground–based pulsed lidar. Ignoring the vertical shear was shown to overestimate the kinetic energy flux of these profiles, in particular for those deviating significantly from a power law profile. As a consequence, the power curve obtained for these deviant profiles was different from that obtained for the ‘near power law’ profiles. An equivalent wind speed based on the kinetic energy derived from the measured wind speed profile was then used to plot the performance curves. The curves obtained for the two kinds of profiles were very similar, corresponding to a significant reduction of the scatter for an undivided data set. This new method for power curve measurement results in a power curve less sensitive to shear. It is therefore expected to eventually reduce the power curve measurement uncertainty and improve the annual energy production estimation. Copyright © 2011 John Wiley & Sons, Ltd.     

Wind turbine load validation using lidar‐based wind retrievals

We define and demonstrate a procedure for carrying out wind turbine load validation based on measurements from nacelle‐mounted scanning lidars. Two coherent Doppler lidar systems, a pulsed lidar and a continuous‐wave lidar, are mounted on a 2.3‐MW wind turbine equipped with load measurement sensors. Wind measurements from a meteorological mast mounted at 2.5 rotor diameters distance are used as reference. The study shows how lidar measurements are processed and applied as inputs to aeroelastic load simulations, and the results are then compared with simulations where the wind inputs have been determined using the meteorological mast data in compliance with the IEC61400‐13 standard. For the majority of simulation cases considered, the use of nacelle‐mounted lidar measurements results in load estimation uncertainties lower or equal to those that are based on measurements from cup anemometers on the mast. These results demonstrate the usefulness of nacelle‐mounted lidars as tools for carrying out load validation without the need of meteorological masts.     

A spinner‐integrated wind lidar for enhanced wind turbine control

A field test with a continuous wave wind lidar (ZephIR) installed in the rotating spinner of a wind turbine for unimpeded preview measurements of the upwind approaching wind conditions is described. The experimental setup with the wind lidar on the tip of the rotating spinner of a large 80 m rotor diameter, 59 m hub height 2.3 MW wind turbine (Vestas NM80), located at Tjæreborg Enge in western Denmark is presented. Preview wind data at two selected upwind measurement distances, acquired during two measurement periods of different wind speed and atmospheric stability conditions, are analyzed. The lidar‐measured speed, shear and direction of the wind field previewed in front of the turbine are compared with reference measurements from an adjacent met mast and also with the speed and direction measurements on top of the nacelle behind the rotor plane used by the wind turbine itself. Yaw alignment of the wind turbine based on the spinner lidar measurements is compared with wind direction measurements from both the nearby reference met mast and the turbine's own yaw alignment wind vane. Furthermore, the ability to detect vertical wind shear and vertical direction veer in the inflow, through the analysis of the spinner lidar data, is investigated. Finally, the potential for enhancing turbine control and performance based on wind lidar preview measurements in combination with feed‐forward enabled turbine controllers is discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

挡流板对垂直轴风力机性能影响的试验研究与分析

在风力机前方安装挡流板可提高H型垂直轴风力机的发电功率,但目前缺少对该结构装置的全面系统研究,且评估安装挡流板时所使用的风能利用系数C_P的计算方法并不恰当,以至于某些计算结果突破贝兹极限,导致概念混淆。文章通过对挡流板安装位置及安装角度进行测试,获取了不同位置的风力发电功率随风轮转速的变化关系。结果表明:在一定距离范围内,挡流板与风轮有一最佳距离,挡流板远离风轮时,提高风速的效果差,挡流板距离风轮越近对来流风干扰变大,输出功率反而降低;挡流板的最佳安装角度为90°,安装角小于或者大于90°时,风速变化平缓,输出功率增长减弱,失去聚风作用。考虑到挡流板聚风后叶轮前的风场不均匀,在计算C_P时不能取某一个风速值或用平均值代入其定义式,文章提出了采用平均风动能的统计方法计算C_P,计算结果表明,增加挡流板可以提高输出功率,但不一定能增加C_P值。     

Modelling and measurements of power losses and turbulence intensity in wind turbine wakes at Middelgrunden offshore wind farm

Understanding of power losses and turbulence increase due to wind turbine wake interactions in large offshore wind farms is crucial to optimizing wind farm design. Power losses and turbulence increase due to wakes are quantified based on observations from Middelgrunden and state‐of‐the‐art models. Observed power losses due solely to wakes are approximately 10% on average. These are relatively high for a single line of wind turbines due in part to the close spacing of the wind farm. The wind farm model Wind Analysis and Application Program (WAsP) is shown to capture wake losses despite operating beyond its specifications for turbine spacing. The paper describes two methods of estimating turbulence intensity: one based on the mean and standard deviation (SD) of wind speed from the nacelle anemometer, the other from mean power output and its SD. Observations from the nacelle anemometer indicate turbulence intensity which is around 9% higher in absolute terms than those derived from the power measurements. For comparison, turbulence intensity is also derived from wind speed and SD from a meteorological mast at the same site prior to wind farm construction. Despite differences in the measurement height and period, overall agreement is better between the turbulence intensity derived from power measurements and the meteorological mast than with those derived from data from the nacelle anemometers. The turbulence in wind farm model indicates turbulence increase of the order 20% in absolute terms for flow directly along the row which is in good agreement with the observations. Copyright © 2007 John Wiley & Sons, Ltd.     

Investigation of wind turbine wake superposition models using Reynolds‐averaged Navier‐Stokes simulations

It is well accepted that the wakes created by upstream turbines significantly impact on the power production and fatigue loading of downstream turbines and that this phenomenon affects wind farm performance. Improving the understanding of wake effects and overall efficiency is critical for the optimisation of layout and operation of increasingly large wind farms. In the present work, the NREL 5‐MW reference turbine was simulated using blade element embedded Reynolds‐averaged Navier‐Stokes computations in sheared onset flow at three spatial configurations of two turbines at and above rated flow speed to evaluate the effects of wakes on turbine performance and subsequent wake development. Wake recovery downstream of the rearward turbine was enhanced due to the increased turbulence intensity in the wake, although in cases where the downstream turbine was laterally offset from the upstream turbine this resulted in relatively slower recovery. Three widely used wake superposition models were evaluated and compared with the simulated flow‐field data. It was found that when the freestream hub‐height flow speed was at the rated flow speed, the best performing wake superposition model varied depending according to the turbine array layout. However, above rated flow speed where the wake recovery distance is reduced, it was found that linear superposition of single turbine velocity deficits was the best performing model for all three spatial layouts studied.