基于多体模型的水平轴风力机气弹耦合分析

大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element,SE)将柔性构件离散为带有力元弹簧和阻尼器的旋转铰连接的有限个数的刚体。基于多体系统(Multi-body system,MBS)动力学理论和混合多体系统(Hybrid multi-body systems,HMBS)的建模方法,通过编制的仿真程序自动建立受约束的风力机多体系统动力学方程并进行数值求解。通过傅里叶谱分析方法,实现了系统动力学特性分析。算例分析美国可再生能源实验室(National renewable energy laboratory,NREL)公布的5 MW水平轴近海风力机的固有频率与振型,验证了程序的有效性和建模方法的正确性。基于叶素动量(Blade element momentum,BEM)理论,计算叶片变形状态下各刚体所受的气动力,在数值积分过程中实时实现流固之间的耦合。分析结果表明超级单元能用较少的自由度准确地描述风力机气动载荷、惯性力和弹性力三者之间的耦合。所开发的仿真程序能为风力机气弹耦合及稳定性分析和控制系统设计提供实用的分析平台。     

多体动力学模型的Modelica语言建模

对Adams多体模型结构及Modelica模型的转换方法进行了研究。对多体动力学模型结构及建模方式进行分析,根据Adams多体模型结构设计了对应的Modelica多体模型结构。研究了Adams多体模型各组件包含的信息,以及与Modelica模型的异同,提出了各多体组件的转换方法。最后给出了多体模型转换验证实例与结果。该研究有助于提高多领域仿真系统的多体建模效率及与传统多体系统的兼容性。     

复合材料风力机叶片的有限元建模

给出了直接应用ANSYS软件对复合材料风力机叶片建立有限元模型的方法,介绍了通过ANSYS的GUI操作界面的建模过程及步骤。直接用ANSYS建立模型避免了Pro/E、Solidworks、UG等三维软件与有限元软件相互转化的过程中数据丢失,实体失真等现象,更真实更准确地反映了复合材料叶片的实际结构性能。     

大型风力机叶片三维建模方法的研究

由于大型风力机叶片结构复杂,为了分析叶片的工作性能,目前主要运用专门开发的软件,或采用三维建模软件与有限元软件结合起来的方法。这种分析方法的过程中,存在着诸如其他三维软件与ANSYS软件之间的不确定的格式等问题。针对这样的问题,提出一种在有限元软件ANSYS上直接建立叶片三维模型的方法;并且在目前叶片截面的翼型坐标计算式的基础上,改进其计算过程,使得计算结果更加精确。最后利用ANSYS软件完成叶片的三维建模,整个建模过程精确,简洁,方便。     

基于UG的风力机叶片参数化建模方法研究

对风力机中最关键和最基础的部件--叶片进行了参数化建模方法的研究.结合坐标变换关系,运用EXCEL强大的数据处理功能,对叶片翼型上各离散点数据进行处理,得到各离散点空间坐标;基于UG的自由曲面造型功能,采用三次B样条拟合方式绘制了叶片截面的空间样条曲线,构建了该风力机叶片的空间三维模型.提出的方法,大大提高了建模效率.为后续结构强度、叶片的力学特性计算提供基础.     

大变形曲梁多体系统动力学建模

为了提高大变形曲梁多体系统数值仿真的计算精度和计算效率,引入弧线坐标,采用曲梁单元,从非线性应变关系式出发,用绝对节点坐标法建立了大变形曲梁多体系统的动力学模型,该方法的特点是不需要引入单元转换矩阵,收敛性好。用曲梁单元模型对曲梁单摆进行数值仿真计算,将计算结果与将曲梁细化为若干个直梁单元的动力学模型的计算结果进行对比,验证了曲梁单元动力学模型的准确性和有效性。在此基础上用曲梁单元模型实现了四连杆曲梁多体系统的动力学仿真。     

基于MATLAB的风力机叶片自动化有限元建模

叶片是风力机获取风能最为关键的部件之一。近年来,有限元技术已经广泛地运用到风力机叶片设计和分析中。然而,由于风力机叶片极为复杂的曲面外形和铺层结构,使得叶片有限元建模变成一项极具挑战性和耗时的任务。为了提高风力机叶片设计和分析的效率,本文结合Matlab语言和APDL(Ansys参数化设计语言)编程,开发了Matlab GUI(用户图形界面),能够在完成风力机叶片几何外形设计的同时,自动生成用于建立叶片有限元模型的APDL命令流。本文以一台10kW定桨距失速型风力机叶片的设计和有限元建模为实例,阐述其思想并验证了此方法的高效性、正确性和实用性。     

柔性多体系统混合递推动力学建模及实时仿真研究

进一步发展了空间算子代数理论体系,采用空间算子描述了广义柔性多体系统动力学高效率建模以及实时仿真问题。根据不同类型的铰链特征(主动关节、被动关节)描述了广义柔性多体系统特征,按照两次从系统顶端到基座和一次从基座到顶端的顺序分别计算系统的广义铰接体惯量算子、系统的冗余力算子以及广义加速度和广义主动力矩,进而建立广义柔性系统O(N)阶动力学模型。采用线性多步积分算法理论解决了大型微分代数方程的数值积分算法,实现了实时动力学仿真的目的。最后通过实例结果对比验证了研究内容的正确性和高效性。     

柴油机多体动力学建模时曲轴有限元模型的验证与精度研究

以某型柴油机曲轴为研究对象,对其进行三维实体建模,并建立其有限元模型.在通过试验对曲轴自由模态分析模型修正的基础上,讨论曲轴约束模态分析时有限元的建模方法;在此基础上,通过曲轴的约束模态试验验证曲轴的约束模态分析模型,得到了柴油机多体动力学分析时精度较高的曲轴约束模态模型的建模方法.文中的建模方法提高了模型的精度和可信度,可应用于其它机械零部件.     

基于混合仿生设计的风力机塔架

本文为风力机塔架的混合仿生设计提供了一种方法。为提高风力机机组整体安全性,基于混合仿生设计方法,提取竹子竹节和问荆草茎截面特征,构造了由外塔筒、内塔筒、法兰盘（加强节）和加强肋板组成的两种仿生塔架（FS1和FS2）。运用ANSYS Workbench软件对比研究原型塔架和两种仿生塔架的静动态性能和屈曲稳定性。结果表明：内塔筒为圆形的FS1塔架力学性能更好。与原型塔架相比,FS1塔顶最大位移和门洞附近的最大等效应力分别降低了17.6%和23.83%,1阶固有频率和1阶临界屈曲载荷分别提高了5.2%和23.12%,充分证明仿生塔架FS1具有更好的抗弯性能和稳定性。     

风力发电机组增速箱传动比研究

增速齿轮箱作为风电机组中最重要的传动部件,负责将风轮叶片的低转速转换为发电机所需要的高转速,实现能量与扭矩的高效传输,具有结构紧凑、载荷复杂、升速比高等特点.主要介绍了风电机组增速齿轮传动的特点,对增速箱总传动比的匹配原则和各级传动比的分配原则进行了研究,利用试验方法和MATLAB软件讨论了传动比对增速齿轮箱传动噪声的影响.     

Optimization model for rotor blades of horizontal axis wind turbines

This paper presents an optimization model for rotor blades of horizontal axis wind turbines. The model refers to the wind speed distribution function on the specific wind site, with an objective to satisfy the maximum annual energy output. To speed up the search process and guarantee a global optimal result, the extended compact genetic algorithm (ECGA) is used to carry out the search process. Compared with the simple genetic algorithm, ECGA runs much faster and can get more accurate results with a much smaller population size and fewer function evaluations. Using the developed optimization program, blades of a 1.3 MW stall-regulated wind turbine are designed. Compared with the existing blades, the designed blades have obviously better aerodynamic performance. __________ Translated from Journal of Shantou University (Natural Science), 2006, 21(1): 44–49 [译自: 汕头大学学报 (自然科学版)]     

A continuous force model for the impact analysis of flexible multibody systems

A new continuous impact model applicable to multibody systems consisting of interconnected rigid and flexible bodies is presented. The continuous impulsive force that acts during the short-lived interval of impact is written in terms of the relative displacement and velocity of the impacting bodies. In the method developed in this paper, the material compliance and damping coefficients are determined from energy balance relations. In order to account for the kinematic constraints between the two impacting bodies and other bodies in the system, an effective mass compensation is proposed. Flexible bodies in the system are discretized using the finite element methods. The generalized impulsive forces associated with the system generalized coordinates are then derived using the virtual work and are written in terms of a coupled set of reference and modal elastic coordinates. Numerical examples are presented in order to demonstrate the feasibility of the mathematical model developed in this paper.     

电网扰动故障下双馈风电机组建模及模型验证

针对分析风电机组并网对系统稳定性影响,需要建立风力发电机的模型的问题,对电网扰动故障下双馈风电机组的模型进行研究,并且开展了模型有效性验证。首先,建立了用于电力系统仿真计算的包括电网扰动模型、双馈发电机模型、变流器模型、风轮模型、传动链模型、变桨模型、变速变桨控制模型等的双馈风电机组模型。然后以WD77-1500型双馈风电机组为例子,在Matlab/Simulink环境下,搭建出该机型的仿真模型,并研究双馈风电机组在电网扰动故障下的动态响应特性;最后,通过分析对比模型仿真结果和现场低电压穿越测试结果,验证了该模型的正确性和有效性。模型验证结果表明,所搭建的风电机组模型适用于后续的风电场建模和研究对电力系统稳定性的影响,具有重要的工程应用价值。     

A bond graph approach to the modeling of general multibody dynamic systems

A vector bond approach which effectively leads to a compact form of Hamiltonian bond graph structure and naturally to Hamilton’s equation of motion is proposed for the modeling of general multibody dynamic system. The methods for determining required bond graph elements are formulated in terms of kinematic influence coefficients. All moduli of transformers and their time rate of changes are found by pure vector (matrix) operations for the readiness for computer simulation of the resulting bond graph.     

Fatigue life evaluation of pinion gears for the reliability of pitch systems in wind turbines

The recent development in the eco-friendly energy industry has motivated many researchers to focus on wind turbines. The advancement of wind turbine technology is in accordance with the trends in the last century. Pitch systems, which comprise wind turbines, have a high failure rate. However, the fatigue life of pitch systems has not been sufficiently studied. A pitch system, which greatly affects the power generation efficiency of a wind turbine, consists of a motor, a gearbox, and a pinion. In this work, a fatigue life analysis of a pinion is performed to improve the durability of pitch systems. Frequent changes in rotation are unique to a pitch system in operation. When an impact load exists at an inverse turn, the stress generated from the impact load is the dominant factor to consider in evaluating the fatigue life of a pinion. The stress history at the gear tooth is determined through a finite element simulation. The cumulative damage fraction is calculated via rainflow cycle counting on the basis of the Goodman relation and Miner’s rule. Therefore, we propose a method for evaluating the fatigue life of a pinion, which considers the effect of an impact load. A conservative design of pitch systems is needed to ensure the reliability of wind turbines under an impact load.

     

风电机组耦合系统的模态分析

针对风电机组设计如何避免耦合共振的问题,采用拉格朗日方法,建立了风轮动力学方程和塔架耦合系统动力学方程,联立获得了风电耦合系统动力学方程,以市场成熟的1 500 k W变速变桨双馈机组为研究对象,解耦获得了系统模态参数。然后展开了现场实测工作,挑选云南某风电场1 500 k W机组,实测了风轮系统和塔架耦合系统模态数据,进行了数据分析,研究了风电系统整机运行稳定性。研究结果表明:理论模型及各子系统边界连接条件简化方式符合现场实际情况,最大偏差为8.6%,具有较高的精准性,该理论模型可为兆瓦级风电机组研发、设计和优化提供理论指导依据。     

风力发电机混合式刹车系统的电磁涡流刹车研究

针对现代风力发电机刹车系统存在的齿轮箱所受扭矩大、刹车片磨损快等问题,提出了用电磁涡流刹车作为风力发电装置辅助刹车的混合式刹车系统.试验结果表明,该新型刹车系统刹车性能较好,并且解决了上述问题.     

Measurement system for wind turbines noises assessment based on LabVIEW

An automatic measurement platform based on powerful LabVIEW is designed and implemented for noise assessment of Wind Turbine Generator Systems (WTGS). The measurement method of IEC 61400-11 standard is set-up in order to ensure the consistency and accuracy of noises assessment. Firstly, the techniques of measuring wind speed, calculating apparent sound power at integer wind speed, identifying tonality and audibility at integer wind speed recommended in IEC 61400-11, are described briefly. And then, the measurement system is designed using LabVIEW development system with one PCMCIA card and one USB card inserted into a laptop. The whole system architecture with the hardware configures and software function modules, is introduced in detail. Finally, this system is applied to do noises assessing for GOLDWIND 77/1500 wind turbine and the results have been recognized by the authoritative agency of MEASNET. Benefiting from the module design of sub-virtual instrument in LabVIEW, this system has the characteristics of perfect functions, friendly using interface, high integration, low cost and great practicality. It has wide foreground for noises assessment of WTGS.     

风力机叶片设计的新方法

根据水平轴风力机转子的涡流气动模型，从能量的角度入手，考虑干涉因子和翼型阻力，提出了叶片翼型设计的一种新型计算方法。