考虑空气密度变化的风电机组转矩控制算法研究

为了研究在不同空气密度条件下转矩控制修正算法对风电机组功率提升的影响,文章分析了空气密度与最优转矩控制的关系。结合风电场实际测量数据,总结空气密度的变化特点及规律,设计了考虑空气密度变化的最优转矩控制修正算法。利用Bladed软件,在湍流风况下设计了不同空气密度时,有、无空气密度修正的5组对照实验。实验结果表明,空气密度变化直接影响机组的输出功率,但是针对转矩控制的直接修正算法对风电机组发电功率提升效果不明显,有待进一步的综合优化。     

超大型风电机组叶片颤振分析及参数灵敏度研究

以IEA 15 MW参考风电机组为研究对象，基于修正的极坐标网格叶素动量理论与Timoshenko梁模型，建立叶片气弹耦合分析模型，综合时域和频域方法，分析超大型风电机组叶片失控状态下的气弹稳定性。结果表明，叶片发生颤振失稳，临界颤振速度为13.06 r/min，颤振频率为3.68 Hz，颤振模态主导振型为三阶向前挥舞模态伴随一阶向前扭转模态。此外，定量分析临界颤振速度对于空气密度、叶片质量、截面重心、挥舞刚度和扭转刚度变化的灵敏度。分析表明，扭转刚度是影响临界颤振速度的主导因素，通过减少叶片质量和前移截面重心，增大挥舞刚度和扭转刚度，可提高颤振裕度。采用高空气密度的设计条件，可获得更保守的设计额定转速。     

非能动风电机舱三维仿真模拟研究

通过对风电机舱进行简化后建立模型,对风电机舱三维仿真模拟计算,得到风电机舱内部空气温度、空气密度和空气流速的变化三维特征分布云图,进而得到冷却空气在三维机舱空间内部流动变化的规律特点。从理论上验证加装聚风导流罩,可有效建立起风电机舱跟外界空气所形成的自然循环通风冷却系统,从而可进一步降低夏季高温天气时风电机组的故障率,提高风力发电公司的经济效益和社会效益。     

双馈风电机组叶片变化对低电压穿越性能的影响研究

风电机组的低电压穿越能力主要采用现场测试的方式考核。由于同种类型和容量的风电机组通常采用多种长度的叶片配置,在其中一种叶片长度的机组完成低电压穿越测试后,是否必须对其它叶片长度的机组进行重新检测是目前制造商和检测机构面临的问题。针对该问题,文章首先分析了不同的风轮直径引起风电机组低电压穿越过程中机械功率、发电机转速、桨距角、有功功率和无功功率等状态量的变化,提出风轮直径变化对机组各部件低电压穿越特性的影响程度;其次,采用Bladed与Matlab联合仿真模型,在与实测数据对比校验其仿真准确性后,通过设置Bladed模型中详细的叶片、传动链等机械参数,仿真对比不同风轮直径的风电机组各环节状态变量的区别,验证了理论分析的有效性;最后,以77 m和82 m风轮直径的1.5 MW风电机组低电压穿越测试数据进行对比分析,进一步验证了理论分析和仿真结果的正确性。研究表明,在一种叶片长度的双馈风电机组完成低电压穿越检测后,采用其他长度叶片的风电机组可通过模型仿真方式对其低电压穿越性能进行分析和评估。     

基于重量模型的风力发电机叶片设计问题的研究

以空气动力学、结构动力学和机械工程学为理论基础,分析了影响叶片重量的主要设计因素.在考虑风电机组叶片设计因素的前提下,利用机理分析法建立了风力发电机组叶片的重量模型.通过实际机型的数据验证了模型的合理性,说明利用重量模型研究风电机组设计的方法是可行的.     

叶片覆冰对抗冰冻机组疲劳载荷的影响研究

风电机组叶片覆冰后叶片质量增加、翼型气动性能变化,引起风轮质量不平衡与气动不平衡。机组的载荷特性发生变化,将对关键部件的疲劳载荷产生影响,进而影响机组的安全性与可靠性。文章依据IEC标准对覆冰工况的要求,在考虑叶片覆冰后叶片质量与气动性能变化的基础上,提出两种不同的寿命周期,来研究叶片覆冰状态及覆冰时间对风电机组关键部件等效疲劳载荷的影响,结果表明叶片不均匀覆冰、覆冰时间及低温环境空气密度对机组关键部件疲劳载荷有较大影响。     

叶片变桨速率对风电机组停机过程载荷特性影响研究

分析叶片变桨速率对于风电机组机械载荷影响的机理,并基于某2.5 MW双馈型风电机组载荷实测数据,对相同外部条件不同叶片变桨速率停机过程的载荷数据进行分析,研究叶片变桨速率对风电机组疲劳与极限载荷的影响。运用GH Bladed软件,对不同叶片变桨速率停机工况下的风电机组载荷进行仿真计算,验证叶片变桨速率与风电机组载荷之间的内在关系。现场测试数据与仿真结果均表明,风电机组停机过程中的载荷特性与叶片变桨速率相关,且随着叶片变桨速率的增加,疲劳与极限载荷随之明显增加。由叶片变桨速率增大导致的风电机组极限载荷增加比例与疲劳等效载荷增加比例相近。     

风电机组叶片故障仿真与状态判别研究

该文利用Bladed软件模拟叶片覆冰和破损故障,通过对比和分析风电机组叶片故障与正常时的运行数据,发现叶片故障状态时的机组运行参数变化特征;然后利用叶片振动信号,基于叶片工作模态分析理论识别出叶片模态参数,根据模态参数的变化揭示了两种故障对叶片振动影响的区别;最后将所识别的叶片模态参数与风电机组的运行参数组成多源数据,采用LightGBM框架下的分类决策树算法实现了对叶片故障状态的有效判断和识别。     

风电机组叶片桨距角安装偏差故障诊断

研究了风电机组叶片桨距角安装偏差对风轮气动平衡的影响.首先,在GH Bladed软件中对陆上某5 MW风电机组单叶片桨距角安装偏差进行模拟,分析机组单叶片存在不同偏差角时机组的动态响应;其次,分析叶片桨距角安装偏差对机组叶轮转速、叶尖变形量和叶根弯矩等参数的影响规律,提出一种风电机组桨距角安装偏差方向的识别方法;最后,...     

基于数据特性分析的风电机组叶片结冰辨识

风电机组叶片结冰影响叶片的气动特性,降低机组的输出功率并形成安全隐患。及时、准确判定叶片结冰,有利于提高风电机组运行可靠性和做出运维应对决策。文章通过分析风电能效指标变化特性、部件振动特性、测风仪测值波动特性,选取与叶片结冰相关的SCADA中耦合变量,利用SVR回归算法挖掘耦合参数的历史样本特征值,构建叶片结冰辨识模型。现场数据验证表明,基于SCADA实时数据分析与设备监测结果完全一致,判定准确。模型只通过对实时数据分析判断,无需额外增设硬件,具有较好的实用价值。     

Predictions of ice formations on wind turbine blades and power production losses due to icing

Prediction of ice shapes on a wind turbine blade makes it possible to estimate the power production losses due to icing. Ice accretion on wind turbine blades is responsible for a significant increase in aerodynamic drag and decrease in aerodynamic lift and may even cause premature flow separation. All these events create power losses and the amount of power loss depends on the severity of icing and the turbine blade profile. The role of critical parameters such as wind speed, temperature, liquid water content on the ice shape, and size is analyzed using an ice accretion prediction methodology coupled with a blade element momentum tool. The predicted ice shapes on various airfoil profiles are validated against the available experimental and numerical data in the literature. The error in predicted rime and glime ice volumes and the maximum ice thicknesses varies between 3% and 25% in comparison with the experimental data depending on the ice type. The current study presents an efficient and accurate numerical methodology to perform an investigation for ice‐induced power losses under various icing conditions on horizontal axis wind turbines. The novelty of the present work resides in a unified and coupled approach that deals with the ice accretion prediction and performance analysis of iced wind turbines. Sectional ice profiles are first predicted along the blade span, where the concurrence of both rime and glaze ice formations may be observed. The power loss is then evaluated under the varying ice profiles along the blade. It is shown that the tool developed may effectively be used in the prediction of power production losses of wind turbines at representative atmospheric icing conditions.     

Wind turbine power and sound in relation to atmospheric stability

Atmospheric stability cannot, with respect to modern, tall wind turbines, be viewed as a ‘small perturbation to a basic neutral state’. This can be demonstrated by comparison of measured wind velocity at the height of the rotor with the wind velocity expected in a neutral or ‘standard’ atmosphere. Atmospheric stability has a significant effect on wind shear and increases the power production substantially relative to a neutral atmosphere. This conclusion from Dutch data is corroborated by other published wind shear data from the temperate climate zone. The increase in wind shear due to atmospheric stability also has a significant effect on the sound emission, causing it to be substantially higher than predicted from near‐ground wind velocity and a neutral atmosphere, resulting in a higher noise impact on neighbouring residences. Several measures are proposed to mitigate the noise impact. To reduce noise levels, the rotational speed can be controlled with the near‐ground wind speed or sound level as the control input. To reduce the fluctuation in the sound (‘blade thumping’), it is suggested to adjust the blade pitch angle of the rotating blades continuously. To prevent stronger fluctuations at night due to the coincidence of thumps from several turbines, it is suggested to add random variations in pitch angle, mimicking the effect of large‐scale turbulent fluctuations in daytime. Copyright © 2007 John Wiley & Sons, Ltd.     

考虑叶片旋转及土-结构相互作用对风电结构动力特性影响的研究

风力发电建设场地土特性及叶片转速变化会引起风力发电机动力特性及响应发生变化。基于西北地区某风电场的2 MW三桨叶水平轴风力发电机,利用ANSYS软件建立风力发电机整机模型,考虑叶片旋转及土-结构相互作用对风力发电机动力特性的影响,研究风力发电机在不同叶片转速、不同场地条件及两者共同作用下的动力特性变化规律,并利用坎贝尔图分析上述工况下风力发电机的共振特性。结果表明:叶片转速增加使风力发电机的自振频率逐渐增大,塔筒与叶片的耦合变形使频率增长加快;考虑土-结构相互作用时,风力发电机频率降低,且场地土越软风力发电机频率越小;当两种工况共同作用时,叶片旋转只对一阶频率产生影响,对高阶频率影响甚微,且风力发电机频率降低;考虑叶片旋转时风力发电机在1P转频内不产生共振点,在3P转频内一阶频率的共振点为14 r/min。此外在不同场地土下风力发电机均会产生共振点,其中Ⅲ类土的共振频率最远离额定转频。因此在风电场的场地选择、结构设计及日常运行时应注意其动力特性变化,使其频率远离共振区域,为风力发电机安全运行提供保障。     

基于Park-Gauss模型考虑大气稳定性对布局优化的影响

基于Park模型尾流区线性膨胀假设和径向风速呈高斯分布假设,提出一种新的修正型的工程尾流模型Park-Gauss模型,采用小生境遗传算法,并考虑大气稳定性对风电场布局优化的影响。结果表明:对常风速单风向风电场微观选址布局优化结果是风力机组主要布置在垂直风向的第1排和最后1排;大气边界层稳定性对风电场微观选址布局优化影响显著,在大气边界层不稳定状态下,风电场安装机组总数最多、发电总量及风电场利用效率最高,中性状态和稳定状态依次次之。     

风电场运行对局地边界层气象因素影响

以5 MW风力机组成的风电场为研究对象,采用湍流理论和大气流动特征,分析不同下垫面情况下风电场运行时局地边界层气象因素的变化过程,利用UDF函数编译风电场入口边界条件及不同的地表粗糙度,并利用风洞试验验证模型计算的正确性。研究表明,风电场的存在会减小边界层大气能量并增加湍流动能,具体结果表明:风电场下游风速减小,且风速随着地表粗糙度的增大逐渐降低,速度恢复率逐渐降低;湍动能随着地表粗糙度的增大空间非均匀分布特性更加明显;温度沿垂直方向略微降低,且随着地表粗糙度的增大影响程度加深;同时随着风电场装机规模的不断扩大,其影响范围及程度也增大。     

基于等效风速的风电机组参数对输出功率波动和功率损失特性的影响

以大型三叶风电机组为例,研究发电机组参数对输出功率波动及功率损失的影响.首先建立包括风剪切和塔影效应的等效风速模型,推导输出功率和功率系数的数学模型,研究叶轮半径、塔筒高度、塔筒直径和叶片到塔筒中线的悬垂距离等相关参数对功率波动的频率、幅值、波长、波动区域等特性影响规律.然后建立功率损失的数学模型,研究风电机组参数通过...     

Effects of spatial and temporal resolution of the turbulent inflow on wind turbine performance estimation

The effects of spatial and temporal resolution of wind inflows generated using large eddy simulations (LES) on the scales of turbulence present in the wind inflow, and the resulting changes in wind turbine performance were investigated for neutral atmospheric boundary layer conditions. Wind inflows with four different spatial resolutions and five different temporal resolutions were used to produce different turbine responses. An aero‐elastic code assessed the dynamic response of two wind turbines to the different inflows. Auto‐spectral density functions (ASDF) of turbine responses, such as blade deflection and bending moment, that are representative of the turbine response were used to assess the effect of the inflow. The results indicated that, as additional turbulence scales were resolved, the wind turbines showed a similar increased response that was evident in both the ASDF and variance of the different wind turbine performance parameters. As a result, the amount to which turbulence is resolved in the inflow, particularly using tools such as LES, will be important to consider when using these inflows for wind turbine design and performance prediction. Copyright © 2015 John Wiley & Sons, Ltd.     

Influence of blade rotation on the lightning stroke characteristic of a wind turbine

The blades of a wind turbine rotate during normal operation. To investigate the influence of blade rotation on the lightning‐attracting ability of a wind turbine, a discharge test platform is designed for scaled wind turbines. The 50% impulse voltages and flash probabilities of the scaled wind turbines with gap distances of 1 to 8 m in the static and rotary conditions are determined by using the discharge test and selective discharge test. The discharge test for a single wind turbine with a gap of 1 to 2 m indicates that the breakdown voltages of the gap between the scaled turbine and electrodes increases with an increase in the blade rotation speed. However, the discharge test with a gap distance of 4 to 8 m indicates that the breakdown voltage of the fan decreases with an increase in the blade rotation speed. The test results of the scaled dual wind turbines experiment have the same rules. To explain this phenomenon, the influence of wind speed on the space‐charge distribution and electrical field intensity of corona discharge is simulated in the background of a target thundercloud. The rotation of the fan reduces the space‐charge density near the area of the blade tip, which leads to an increase in the field strength near the blade tip of the wind turbine and a decrease in the field strength away from the blade tip. This influence varies in short and long air gap, resulting in opposite relationships between discharge voltage and distance from the tip of the turbine. The results can provide a reference for the lightning protection of wind turbines.     

Sensitivity of southern California wind energy to turbine characteristics

Using output from a high‐resolution meteorological simulation, we evaluate the sensitivity of southern California wind energy generation to variations in key characteristics of current wind turbines. These characteristics include hub height, rotor diameter and rated power, and depend on turbine make and model. They shape the turbine's power curve and thus have large implications for the energy generation capacity of wind farms. For each characteristic, we find complex and substantial geographical variations in the sensitivity of energy generation. However, the sensitivity associated with each characteristic can be predicted by a single corresponding climate statistic, greatly simplifying understanding of the relationship between climate and turbine optimization for energy production. In the case of the sensitivity to rotor diameter, the change in energy output per unit change in rotor diameter at any location is directly proportional to the weighted average wind speed between the cut‐in speed and the rated speed. The sensitivity to rated power variations is likewise captured by the percent of the wind speed distribution between the turbines rated and cut‐out speeds. Finally, the sensitivity to hub height is proportional to lower atmospheric wind shear. Using a wind turbine component cost model, we also evaluate energy output increase per dollar investment in each turbine characteristic. We find that rotor diameter increases typically provide a much larger wind energy boost per dollar invested, although there are some zones where investment in the other two characteristics is competitive. Our study underscores the need for joint analysis of regional climate, turbine engineering and economic modeling to optimize wind energy production. Copyright © 2012 John Wiley & Sons, Ltd.     

建筑密度对建筑物群内风能利用的影响

针对建筑物群内风能应用问题,采用CFD方法,对建筑密度分别为26%、20%、18%、16%、14%的5种建筑物群周围风速和湍流强度特征开展研究,分析建筑密度对建筑物群内风力机合理安装位置的影响方式。结果表明：在低于1.5H高度范围内,建筑物群的建筑密度越大,同一安装高度上适合于安装风力机的区域就越大,即越有利于建筑物群内风能的应用;在高度高于1.5H后,建筑密度对建筑物群内风力机安装位置的影响消失;无论建筑密度大小,在低于1.2H的高度范围内,建筑物群内不适合安装风力机;在高度高于1.45H后,可优先考虑将风力机安装于建筑物群内中间一排建筑物顶面,在建筑物顶面可优先将风力机安装于拐角位置;5种建筑密度的建筑物群内只考虑风速要求即可确定风力机的合理安装位置。