垂直轴风力发电机的建模与变桨距研究

定桨距垂直轴风力发电机存在启动转矩小和输出效率低的缺点。为了改善垂直轴风电机组的输出特性,在静止和旋转状态下,对6叶片H型垂直轴风力发电机的风轮的受力情况进行了分析。首先建立了H型垂直轴风力机模型,然后对单个叶片变桨距与定桨距下的受力进行了分析,进而对6叶片风力机受力进行了分析。理论分析和仿真结果表明,叶片通过采取变桨距控制,不但有效地改善了H型垂直轴风力机的启动性能,并且减小了输出振动。因此,所提出的变桨距控制方法是可行的。     

H型垂直轴风力发电机的变桨距控制研究

H型垂直轴风力发电机的启动性能差、输出功率低很大程度上影响着垂直轴风力机的广泛使用。主要针对H型垂直轴风力发电机,对各模块进行建模并在MATLAB&SIMULINK中搭建其模型进行仿真,对其采用PID控制策略进行变桨,即在不同位置对叶片进行相应的变桨。最后,将采用PID控制变桨后垂直轴风力机的功率曲线与未变桨时进行对比,验证了采用PID控制的优越性和合理性。     

双叶片直线翼垂直轴风力发电机流场特性分析

针对双叶片直线翼垂直轴风力发电机的流场复杂多变的问题,采用k-ω(SST)湍流模型进行数值模拟,展开了对垂直轴风力发电机流场特性的分析,建立了风速与位置的关系,得到了风速最低位置以及风速恢复区域.研究结果表明,三维CFD仿真所得数据与风洞试验数据虽然有所偏差但对于研究垂直轴风力发电机的流场特性影响较小;通过对垂直于z轴截面和垂直于x轴截面的风速云图分析得出:低风速区域不关于x轴对称,其偏向于y轴负半轴;利用风速值曲线定量得出随着x/R的增大,低风速区的面积逐渐扩散,其值先减小后增大.这为建立垂直轴风力发电厂建立基础.     

改善垂直轴风机效率的叶片转动惯量试验研究

针对风力发电机抗风能力差、使用寿命不佳等特点,选用一种S型垂直轴双层叶片结构的风力发电机对试验风机进行改进.在风机叶片边沿上采用加厚型设计(作为一种配重),从而增加风轮的转动惯量,延长发电机的工作时间.正交试验和方差分析表明,转动惯量的改变可使风机的转化效率从36.12％提升到37.72％.     

基于虚拟仪器的风力发电机效率测控系统设计

为提高垂直轴风力发电机风能利用率,在变风速情况下的发电机能量转移分析的基础上,提出一种发电机能量流向主动控制的方法.通过在发电机和负载之间添加受控能量调节网络,实现发电机在不同风速下能量的受控流动,从而优化提高变风速下风力发电效率.基于该方法,设计了一套基于虚拟仪器的风力发电机效率测控系统.系统由垂直轴风力发电机、谐振...     

垂直轴潮流能发电机组控制系统设计

为了响应国家发展战略,建立良好、可持续、稳定、长久发展的生态环境,达到节约有限资源,提高能源利用率的目的,本文提出了一种垂直轴潮流能发电机组控制系统的设计,设计采用H型垂直轴叶轮,由3个叶片组成,通过海水潮流涨落潮的水流冲击叶轮,叶轮转动带动增速器旋转,从而带动发电机转动进行发电.由于发出的电未能达到国家电网的标准,还...     

堡盟用于直驱式风力发电机的无齿轮多圈绝对值编码器

1引言 风力发电机具有悠久的历史,它发源于古老的风车。早在十九世纪末期,首套发电设施就已经问世。今天,可再生能源市场竞争非常激烈,现代风力发电机必须满足最严苛的性能要求和成本效益要求。可靠性、安全性和有效性是零部件选择的关键标准。当然,用于转子叶片的位置反馈和桨距控制用编码器也不例外。以下应用描述了带电池缓冲保护的多圈绝对值编码器是如何再次通过工业实践的检验的。     

H型垂直轴风力机设计参数分析研究

采用多流管理论模型对风光能源复合发电装置项目中H型垂直轴风机参数进行优化设计,在多流管理论基础上建立模型并用Matlab软件进行计算、仿真。分析了H型垂直轴风力机叶片在旋转过程中不同叶尖速比时攻角的变化情况,以及叶尖速比、密实度对风力机风能利用系数的影响。通过各个参数大小的变化对功率系数的影响进行比较,得出最大功率时所对应的风机最佳参数。     

风力发电机叶片雷击损害机理及有效防护

近几年新建的风电场都选址高山,但随之而来的是风力发电机叶片受雷击的风险也进一步加大。风力发电机叶片作为最容易受到雷击损害的部件,我国在此方面的研究还相对较少,在具体的防护工作中也未能起到良好效果。对比,本文就风力发电机叶片雷击损害的机理及防护措施进行简单的分析与思考,并提出一些可供参考的意见与措施,以期对我国风力发电的叶片防护工作起到一定的促进作用。     

低温型风力发电机叶片缺陷自动检测方法研究

针对人工检测发电机叶片缺陷时存在的检测结果不精准,检测时间较长的问题,以低温型风力发电机为研究对象,设计了一种基于机器视觉的叶片缺陷自动检测方法。在分析叶片缺陷特征及参数的前提下生成叶片缺陷图像,利用数字图像处理技术对叶片缺陷图像进行灰度化与滤波处理,采用通域递归法提取叶片的缺陷特征并构建最优阈值,最后利用机器视觉技术,实现发电机叶片缺陷的自动检测。在MATLAB平台内模拟发电机叶片缺陷的检测过程,结果显示,基于机器视觉的检测方法能够准确检测出发电机叶片表面的擦痕、裂纹等缺陷,较人工检测精准度高26.7%,且检测耗时较短,说明机器检测具备有效性。     

On wind turbine blade design optimization

A wind turbine with a horizontal rotation axis is considered in the stationary airflow. A problem of choosing the law of change of the setting angle of the cross section of the wind turbine blade and the value of the angular speed so that the wind energy utilization coefficient is maximal is discussed. Maximization of the respective functional is considered as a variational problem with a priori unknown parameter. Once it is solved numerically or analytically, the optimal value of this parameter is determined, with the sought variables given by rather simple formulas. The results are analyzed on a qualitative level. In particular, the setting angle is found to change monotonically along the blade, which is confirmed by practical wind turbine design. Examples of using the proposed approach to wind turbine blade design are considered.     

On the Dynamics of Small Wind Power Generators

Based on the previously developed closed mathematical model, the dynamics of a small horizontal axis wind turbine are studied. The procedure for identifying the aerodynamic torque is proposed for the case when the electromechanical interaction is nonlinear in a current. Elements of the system for the comparative analysis of different wind turbines are developed. The results of simulating the behavior of the device are compared with the available experimental data. It is shown that good agreement takes place. The behavior of the system under a changing wind is studied.     

Dynamic analysis of a vertical axis wind turbine using a new windload estimation technique

A new aerodynamic model for obtaining the performance characteristics of a vertical axis wind turbine (VAWT) developed by the authors has been used to obtain estimates of aerodynamic loading, which are subsequently used for the dynamic analysis of a VAWT. The model incorporates gyroscopic effects, structural damping and also power generation through an induction or synchronoustype generator. A computer code written in MS-DOS FORTRAN has been developed for the dynamic analysis of a vertical axis wind turbine, and has been implemented on an IBM compatible 386 AT, for studying the dynamic characteristics of a VAWT. The results obtained from this analysis compare fairly well with other published theoretical and experimental data, and demonstrate that the incorporation of the new wind loading estimation model leads to a definite qualitative improvement in the theoretical predictions of the dynamic characteristics of vertical axis wind turbines.     

风机流场并行数值模拟在集群系统上的应用

介绍集群系统的特点及其软硬件配置环境。利用计算流体力学商用软件Fluent对一种新型垂直轴风力机风轮在曙光天潮超级服务器4000A集群上进行数值模拟及并行计算,得到风轮内外部的三维流场,实现该软件在高性能并行计算机上的应用,为并行有限元分析提供一个基础计算平台。     

Integrated aero-structural optimization of wind turbines

The present work describes methods for the integrated aero-structural optimization of wind turbines. The goal of the algorithms is to identify the structural and aerodynamic design characteristics that achieve the minimum cost of energy for a given wind turbine configuration. Given the strong couplings that exist between aerodynamic and structural design choices, the methods are formulated so as to address both problems simultaneously in an integrated manner, resulting in tools that may help avoid suboptimal solutions or lengthy design loops.All methods considered herein use the same high fidelity multibody aeroservoelastic simulation environment and operate the design according to standard certification guidelines. The methods, however, differ in the way the optimization is conducted, realizing different tradeoffs amongst computational efficiency, generality, level of automation and overall robustness.The proposed formulations are exercised on the design of a conceptual 10 MW horizontal axis wind turbine, illustrating the main characteristics of the various methods.     

大规模风力发电系统暂态分析与综合评估

随着风电等新能源的大规模接入,电力系统的暂态安全稳定问题日益凸显。使用不同的模型和研究方法分析双馈机对电网稳定的影响会得出不同的结论,因此研究暂态稳定需要结合实际电网进行。首先对风电系统的暂态稳定机理进行分析,然后运用一种新型综合评估法对哈密电网十四个主要风电场并网母线的暂态稳定性进行了评估找出系统电压薄弱点。最后通过仿真,分析了不同风电渗透率、不同故障位置及不同故障类型下其对电网的影响。仿真结果表明,所提出的综合评估法具有计算量小、综合性强等优势;大规模风电机组接入对系统暂态稳定的影响具有双重性。     

Optimum section selection procedure for horizontal axis tidal stream turbines

Stochastic behavior of renewable energy sources forces designers to optimize the energy converters for the purpose of capturing the maximum amount of available energy. The performance of horizontal axis wind and tidal turbines mainly depends on the geometrical properties such as chord and twist distributions and also the types of sections which are utilized along the blade. The purpose of presented paper is introducing a procedure which can be utilized in order to select the optimum sections for horizontal axis tidal turbines for the purpose of increasing the turbine performance. The presented procedure also can be applied for horizontal axis wind turbines. For the purpose of evaluating the performance of the proposed method, two design types (chord and twist distributions) of tidal turbines are selected as case studies. Power coefficient is considered as objective function, and three types of hydrofoils namely NACA63-8xx, NACA44xx, and RISO-A1-xx are selected as candidate solutions. A blade element momentum theory model is used for calculating the power coefficient. The discrete ant colony optimization algorithm is selected as optimization tool. The results indicate that the utilization of the proposed method will considerably decrease the required process time for obtaining the optimum sections across the blade span, and also it is shown that using different types of sections across the blade span can increase the power coefficient of the turbine. The importance of the proposed method will be significant when various types of hydrofoils and airfoils can be considered as candidate sections across the blade span.

     

Comparison between linear and nonlinear control strategies for variable speed wind turbines

The purpose of this work is to compare some linear and nonlinear control strategies, with the aim of benefiting as well as possible of wind energy conversion systems. Below rated wind speed, the main control objective is to perform an optimal wind power capture while avoiding strong loads on the drive train shafts. To explicitly take into consideration the low speed shaft flexibility, a two-mass nonlinear model of the wind turbine is used for controllers synthesis. After adapting a LQG controller based on the linearized model, nonlinear controllers based on a wind speed estimator are developed. They take into account the nonlinear dynamic aspect of the wind turbine and the turbulent nature of the wind. The controllers are validated upon an aeroelastic wind turbine simulator for a realistic wind speed profile. The study shows that nonlinear control strategies bring more performance in the exploitation of wind energy conversion systems.     

Wind turbine selection for wind farm layout using multi-objective evolutionary algorithms

Wind energy has become the world’s fastest growing energy source. Although wind farm layout is a well known problem, its solution used to be heuristic, mainly based on the designer experience. A key in search trend is to increase power production capacity over time. Furthermore the production of wind energy often involves uncertainties due to the stochastic nature of wind speeds. The addressed problem contains a novel aspect with respect of other wind turbine selection problems in the context of wind farm design. The problem requires selecting two different wind turbine models (from a list of 26 items available) to minimize the standard deviation of the energy produced throughout the day while maximizing the total energy produced by the wind farm. The novelty of this new approach is based on the fact that wind farms are usually built using a single model of wind turbine. This paper describes the usage of multi-objective evolutionary algorithms (MOEAs) in the context of power energy production, selecting a combination of two different models of wind turbine along with wind speeds distributed over different time spans of the day. Several MOEAs variants belonging to the most renowned and widely used algorithms such as SPEA2 NSGAII, PESA and msPEA have been investigated, tested and compared based on the data gathered from Cancun (Mexico) throughout the year of 2008. We have demonstrated the powerful of MOEAs applied to wind turbine selection problem (WTS) and estimate the mean power and the associated standard deviation considering the wind speed and the dynamics of the power curve of the turbines. Among them, the performance of PESA algorithm looks a little bit superior than the other three algorithms. In conclusion, the use of MOEAs is technically feasible and opens new perspectives for assisting utility companies in developing wind farms.