低风速离网型风力发电机的叶片设计

根据内蒙古四子王旗某地2007年逐月平均风速表选取设计风速为6 m/s,根据某型号300 W交流永磁发电机的输出功率特性,利用Matlab编写的叶片优化设计程序,设计了300 W水平轴风力发电机叶片.通过风轮与发电机的匹配,调整叶片参数,使之在小风时具有较高的风能利用系数,提高风力机的效率,在大风时具有较低的风能利用系数,从而达到大风时限速保护的目的.     

风力发电机大风限速保护方法的研究

小型风力发电机面临的最大难题是其可靠性问题,即大风时的限速保护问题.从能量守恒的角度分析了利用风轮与发电机的功率匹配特性实现风力发电机限速保护的可行性.另外,设计了2台风轮与发电机具有不同匹配特性的300 W/26 V风力发电机,为了使其具有可比性,使用了同样型号的发电机.通过实验测试了风轮的机械输出特性、发电机在输出电压不同时的功率特性和整机的功率输出,实验结果表明,风速12 m/s以下时2台风力机输出功率基本相同,风速12 m/s以上时其中1台随着风速的增加功率不断增加,而另外1台随着风速的增加输出功率不再上升,甚至有点下降,与大风机功率特性相似.     

1kW离网型风力发电机的设计

结合内蒙古的风能分布情况研制了1 kW离网型风力发电机,在叶片的设计计算中应用了"以发电机对蓄电池充电特性曲线,设计叶片的空气动力特性及外形"的新设计理念,使叶片在蓄电池的充电过程中与发电机得到很好的匹配.风场测试结果表明,所研制的1 kW风力发电机准确地达到了预期考核指标,该机可作为内蒙古小型风力发电机的更新换代产品进行示范.     

风力发电机风轮与发电机匹配特性的试验研究

为了提高风力发电机的输出性能,针对离网小型风力机的风轮能量转换系统和发电机系统的性能进行了研究。通过对两副风轮、两台发电机进行交叉组合试验,分别采集了尖速比为3～8、风速为7～13 m/s时风力发电机的功率特性,同时还采集了发电机在不同工况下的温度场、扭矩、功率等参数,选出输出特性较好的发电机和风轮,然后将其组合,对其输出特性进行研究,并测试分析了整机的振动特性。寻找影响发电机系统性能及发电机与风轮系统匹配的相关规律及有机结合点。研究结果表明,风轮和发电机组合后的整体性能不是由单一因素决定的,而是由叶片翼型及安装方式、发电机的结构和技术参数等因素共同作用产生的综合效果,发电机的影响尤为明显。     

离网型风力发电机叶片设计方法研究

根据离网型风力发电机实际运行特性,提出根据发电机对蓄电池充电特性曲线、设计叶片的空气动力特性及外形进行叶片设计的新思路,并系统地设计计算了1kW离网型风力发电机叶片。实验结果表明,采用此设计理念可以简化整机的结构、减轻整机重量,所设计的风力机叶片具有低风速运行等特点。     

离网型户用风力发电机性能测试系统的开发

本文为离网型户用风力发电机虚拟仪器性能测试系统的研制 ,利用NI公司推出的软件LabVIEW及相关配套硬件设备 ,设计了风力机基本性能参数的测试系统。通过对风力发电机输出电流、输出电压、大气温度、大气压力、风速等实验数据的分析和处理 ,得到风力发电机输出特性曲线 ,从而为评估和改进风力发电机的性能提供依据     

基于LabVIEW的离网型风力发电机风速-功率特性研究

通过对离网型风力发电机实际运行状态及气象情况的监测,绘制了风速-功率散点图.利用最大似然估计法对风机输出功率曲线进行拟合,结果表明:七次多项式拟合结果最逼近实际工况;二次多项式拟合曲线精度稍差,但表达式简单明了,可快速预测风力发电机发电量.此外,通过对风力发电机发电量的实际值、理论功率曲线预测值以及利用最大似然估计法拟合得到的功率曲线的预测值的对比,结果表明:风力发电机生产厂商提供的曲线只能反映其稳态的风速-功率关系,用来预测风力发电机发电量还存在较大误差;利用最大似然估计法拟合得到的功率曲线预测的风力发电机发电量误差明显偏小.     

离网型风力发电机塔架振动问题的模态分析

对离网型风力发电机模型的塔架振动进行了分析，运用瑞雷法计算其基频，以有限元模态分析和试验测量的方法计算分析出塔架的固有频率和振型。根据分析结果讨论有限元建模的合理性，分析引起振动的原因，并依此提出塔架较合理的锥形管结构改进方案。     

风特性对风力发电机组输出功率的影响

为了准确研究不同类型的风速对并网风电机组输出功率的影响,建立了并网风力发电机模型和不同类型风速的模型。在不同类型风速的扰动下,对异步风电机输出功率的波动进行了仿真分析;针对引起功率振荡最严重的阵风,进行了不同频率的阵风扰动下风电机组功率振荡的比较,对阵风扰动下风电机组间的相互影响进行了仿真分析。结果表明,在相同幅值的扰动下,阵风引起的风电机组功率振荡最严重,机组功率振荡情况与阵风扰动的频率有关,单台机组在阵风扰动下产生的振荡对其他机组也会产生一定的影响。     

Power,structural and noise performance tests on different wind turbine rotor blade designs

Most blades available for commercial-grade wind turbines incorporate a straight, span-wise profile and airfoil-shaped cross-sections. These blades are found to be very efficient at low and medium wind speeds compared with the potential energy that can be extracted. This paper explores the possibility of increasing the efficiency of the blades by modifying the blade design to incorporate a swept edge. The design intends to maintain efficiency at low to medium wind speeds by selecting the appropriate orientation and size of the airfoil cross-sections based on an oncoming wind speed and given constant rotation rate. The torque generated from a blade with straight-edge geometry is compared with that generated from a blade with a swept edge as predicted by CFD simulations. To validate the simulations, the experimental curve of the NTK500/41 turbine using LM19.1 blades is reproduced using the same computational conditions. In addition, structural deformations, stress distributions and structural vibration modes are compared between these two different turbine blade surfaces.     

兆瓦风力发电机系统可靠性设计理论研究

在分析兆瓦风力发电机系统的基础上,提出了兆瓦风力发电机发电系统可靠度的基本概念及计算方法,建立了可靠度最优分配的数学模型及最优兆瓦风机发电系统可靠性设计的数学模型。     

大型水平轴式风电叶片的结构设计

风电叶片是风力发电设备的关键部件之一,其制造成本占总成本的20%～30%.叶片结构是叶片捕获风能的保证,并直接影响风力发电设备的运行寿命.因此,叶片结构设计的好坏在很大程度上决定了风力发电设备的可靠性和利用风能的成本.文章从材料、结构形式、铺层设计、结构分析等4个方面详细地阐述了风电叶片结构的设计技术.     

基于混杂自动机的大型风力发电机组全程控制

风力发电系统是具有不确定性的复杂非线性系统,机组运行工况变化十分频繁。通过对风力发电机组的系统特性分析,发现风力发电系统呈现出混杂系统的典型特征。因此,基于混杂自动机理论建立了1.5 MW双馈型风电机组的混杂动态模型,并根据风力发电机组控制策略设计了能够在机组运行中实现全程自动化的混杂控制系统。仿真结果表明,基于混杂自动机的动态模型可以实现风电机组的全程模拟,所设计的混杂控制系统能够满足风电机组全程控制要求,证明了混杂系统理论应用于风力发电研究领域的有效性。     

兆瓦级海上风力机叶片设计及模态分析

叶片是风力机的重要构件,对其合理设计十分重要。总结了叶片的设计流程,并选择合理的设计参数,设计出兆瓦级风力机的叶片;在三维绘图软件中建模;应用有限元法,选定叶片的材料参数,在有限元软件中对叶片进行模态分析,确定了叶片的各阶模态振型及各阶频率,并对比分析叶片各阶模态振型结果。结果表明,叶片的固有频率范围与外界的激励的频率范围不重合,因此避免了共振破坏的发生。     

Shape optimization of wind turbine blades

This paper presents a design tool for optimizing wind turbine blades. The design model is based on an aerodynamic/aero‐elastic code that includes the structural dynamics of the blades and the Blade Element Momentum (BEM) theory. To model the main aero‐elastic behaviour of a real wind turbine, the code employs 11 basic degrees of freedom corresponding to 11 elastic structural equations. In the BEM theory, a refined tip loss correction model is used. The objective of the optimization model is to minimize the cost of energy which is calculated from the annual energy production and the cost of the rotor. The design variables used in the current study are the blade shape parameters, including chord, twist and relative thickness. To validate the implementation of the aerodynamic/aero‐elastic model, the computed aerodynamic results are compared to experimental data for the experimental rotor used in the European Commision‐sponsored project Model Experiments in Controlled Conditions, (MEXICO) and the computed aero‐elastic results are examined against the FLEX code for flow past the Tjæreborg 2 MW rotor. To illustrate the optimization technique, three wind turbine rotors of different sizes (the MEXICO 25 kW experimental rotor, the Tjæreborg 2 MW rotor and the NREL 5 MW virtual rotor) are applied. The results show that the optimization model can reduce the cost of energy of the original rotors, especially for the investigated 2 MW and 5 MW rotors. Copyright © 2009 John Wiley & Sons, Ltd.     

Open loop wind turbine emulator

A new wind turbine emulator (WTE) is presented, which is able to simulate the turbine power curves without using a closed loop control system. The state of the art emulators use DC or AC motors, closed loop controlled by processors with the turbine power curves recorded. The presented emulator has a DC voltage source, a power resistor and a DC motor with independent excitation. The motor power curve has a shape similar to a wind turbine power curve for a given wind speed; the wind speed variations can be emulated by the variations of the DC voltage source. The open loop emulator is completely different and new, because it works in open loop and does not require the presence of a processor.The following elements are included: the theoretical foundations of the emulator, the emulator power curves adjustment procedure to simulate a commercial wind turbine and the experimental tests.     

并网中小型风电系统最大功率跟踪控制

针对目前中小型风力发电系统发电效率低,提出了一种新型拓扑结构,即机侧采用三相PWM整流器,网侧采用单相PWM逆变器。在对永磁同步发电机数学模型和风力机最佳输出功率进行分析的基础上,采用转子磁链定向控制技术,实现对发电机输出的有功功率的控制,进而实现对风力发电机最大功率的跟踪控制;同时,在单相系统中引入"虚拟电路",使网侧单相变流电路参数可以转化到旋转坐标系下,实现无静差控制。通过仿真试验验证了控制策略的可行性。     

On the structural topology of wind turbine blades

As wind turbines continue to grow in size, it becomes increasingly important to ensure that they are as structurally efficient as possible to ensure that wind energy can be a cost‐effective source of power generation. A way to achieve this is through weight reductions in the blades of the wind turbine. In this study, topology optimization is used to find alternative structural configurations for a 45 m blade from a 3 MW wind turbine. The result of the topology optimization is a layout that varies along the blade length, transitioning from a structure with trailing edge reinforcement to one with offset spar caps. Sizing optimization was then performed on a section with the trailing edge reinforcement and was shown to offer potential weight savings of 13.8% when compared with a more conventional design. These findings indicate that the conventional structural layout of a wind turbine blade is sub‐optimal under the static load conditions that were applied, suggesting an opportunity to reduce blade weight and cost. Copyright © 2012 John Wiley & Sons, Ltd.