海况条件对海上风力发电机组载荷的影响

文章针对海况条件对海上风力发电机组载荷的影响,以某5 MW海上机组为例,介绍海浪、海流和潮汐在载荷计算过程中采用的理论方法和支撑结构建模方法,对支撑结构和海浪能量分别进行模态分析和频谱分析,同时根据GL2005标准对极限载荷和疲劳载荷分不同情况分析,结果表明海况条件对海上机组的塔筒底部影响较大,对机组其他关键零部件影响很小,为大型海上机组关键零部件选取提供依据。     

漂浮式海上风电机组基础竖直向水动力载荷研究

本文基于OC4项目的第二阶段研究,利用Bladed for Windows 4.3建立了三支柱半潜式浮动平台的风电机组模型,并采用Morison方程建立水动力载荷。对比分析了平台在4种不同的初始状态下,竖直方向的水动力载荷对半潜式浮动平台自由振动的影响。     

多载荷耦合作用下的风电机组塔架结构动力学特性研究

文章针对在多载荷耦合作用下的大型风电机组塔架结构动力学参数变化的问题,根据柔性理论在耦合结构中的应用,建立了三维结构动力学模型。利用模态分析法,进行了振动特性研究。利用Solidworks模块化的流体分析嵌入技术进行了多载荷动力学分析。通过风与雨水载荷的耦合作用,结合基本控制方程,分析了塔架的振动位移变化情况。结果表明:振动特性中,最大振幅为0.37 m;在风与雨水耦合作用下,塔架振动位移变化幅值较大,最大值为1.22 m。该结果为塔架在风雨耦合载荷中的动力响应提供参考数据,从而为风电机组运行的稳定性提供一定参考。     

大型风力发电机组地震载荷计算方法研究

随着国家大规模开发风力发电,风力发电机组安全性逐渐受到重视.近年来全国地震时有发生,由于地震很难预测,并且具有很强的破坏性,风力发电机组在地震情况下的安全性必须在设计中考虑.文章介绍了风力发电机组地震设计标准,分析了地震载荷计算原理.最后根据2 MW陆上双馈风力发电机组,分析了地震载荷对风力发电机组各个部件设计的影响,为风力发电机组地震载荷计算提供了参考经验.     

风力电网故障下的机械载荷优化测试分析

风力发电网络受到外界的不确定因素干扰较大,容易产生故障。分析风力电网故障下的电机机械载荷,实现对风力电网的故障诊断。传统方法采用风力电网故障信号采集和特征提取方法,在非线性耦合干扰下对电机机械载荷的测试效果不好。提出一种基于机械载荷线性反馈和谐波抑制的风力电网故障诊断方法,实现对故障下机械载荷优化测试。构建风力电网故障下的机械载荷数据采集和信号生成模型,采用双曲调频信号的自连续小波变换来分析机械载荷的电流信号、差压信号、绝压信号和振动信号,采用机械载荷线性反馈和谐波抑制方法,实现对风力电网故障下机械载荷数据的干扰滤波和特征优化测试,输入到风力电网故障诊断专家系统中,比对故障数据中的可用知识,实现对风力电网故障的准确诊断。仿真结果表明,采用该方法能实现对载荷数据的准确采集和测试,提高风力电网的故障准确诊断性能     

风波联合作用下5MW海上风力机的疲劳载荷特性分析

海上风力机在风和波浪的联合作用下运行,受到风、波浪等产生的随机交变载荷作用,在设计寿命期间要受到超过108的载荷循环,风力机疲劳荷载特性是风力机设计的重要问题。文章以NREL 5 MW单桩式海上风力机为研究对象,采用IEC标准中Kaimal谱模拟风况、莫里森公式模拟海浪,建立海上风力机的动态模型,应用FAST软件研究风力发电机组在IEC疲劳工况下,正常发电、发电出现脱网故障、启动、正常停机的荷载特性,得到叶片、塔筒上的载荷分布等,研究风力机叶片、塔筒载荷变化规律,为风力机结构疲劳寿命损耗估算、优化设计提供可靠依据。     

风力机组偏航变桨轴承载荷分布分析及数值求解

大型风力发电机组偏航和变桨轴承通常采用四点接触球轴承,文章对四点接触球轴承在外载下轴承内部载荷分布进行了详细分析,列出了外载和变形的平衡方程,给出了数值求解的步骤,并用MATLAB编写了求解程序。最后对某型风力发电机组的偏航轴承进行强度校核,为轴承的选型和设计提供依据。     

6 MW漂浮式风电机组极限载荷特性研究

海上风电场建设由近海走向深远海,漂浮式风电机组将会是这一区域最适合的选择。选用华锐6 MW机组,结合东海某海域环境条件和IEC规范,利用气动-水动耦合时域分析方法,对不同基础型式下的风电机组载荷特性进行研究。计算结果表明:漂浮式风电机组叶片、轮毂极限载荷与海上固定式风电机组相比没有明显增加,塔筒底部极限载荷增加幅度可达30%;在正常发电工况和极端空转工况叶片和轮毂极限载荷主要受风载荷控制,而塔筒底部和顶部极限载荷在不同工况受风载荷和波浪载荷影响效果则有不同。     

风浪耦合作用下海上风电机组载荷特性研究

与陆上风电机组不同,海上风电机组承受风载荷以及波浪引起的水动力载荷共同作用。在风浪耦合作用下,海上风电机组基础结构以及各主要结构部件载荷特性更为复杂。为保障海上风电机组的运行结构安全,波浪特性对海上风电机组各主要承载部件载荷的影响应引起重视。该文基于改进的JONSWAP型谱,建立波浪动力学模型,以叶片根部挥舞方向弯矩以及塔筒底部俯仰方向弯矩为例,仿真研究波浪对于风电机组极限与疲劳载荷特性的影响。最后,基于海上风电机组载荷实测与仿真数据,对波浪动力学模型进行验证。     

风力机叶片在三维湍流下的载荷分析

载荷计算是风力机设计中最为关键的基础性工作,也是所有后续风力机设计、分析工作的基础.文章研究了在叶片坐标系下风力机主要载荷的确定方法;应用bladed软件计算稳态风速下的稳态运行载荷,并考虑湍流模型的影响;采用Improved yon Karman模型,将得到风文件加载到bladed里,来计算此风速下的空转运行载荷;最后通过自由频谱图验证整机是否有共振现象.     

浅析海上风电机组的散热布置

海上风电发展前景广阔,开发大容量海上风电机组所面临的主要问题包括如何有效地冷却发电机、齿轮箱及变频器等核心部件。通过分析某MW级海上风电机组冷却系统的散热器空间布置形式、散热通道结构设计以及散热器所配风扇性能,利用CFD软件对散热通道内流场进行了三维数值模拟,结果表明,散热器的布置形式直接影响散热通道的系统阻力,进而影响散热器所配风扇与系统的特性匹配。     

Long‐term loads for a monopile‐supported offshore wind turbine

Accurate prediction of long‐term ‘characteristic’ loads associated with an ultimate limit state for design of a 5‐MW bottom‐supported offshore wind turbine is the focus of this study. Specifically, we focus on predicting the long‐term fore–aft tower bending moment at the mudline and the out‐of‐plane bending moment at the blade root of a monopile‐supported shallow‐water offshore wind turbine. We employ alternative probabilistic predictions of long‐term loads using inverse reliability procedures in establishing the characteristic loads for design. Because load variability depends on the environmental conditions (defining the wind speed and wave height), we show that long‐term predictions that explicitly account for such load variability are more accurate, especially for environmental states associated with above‐rated wind speeds and associated wave heights. Copyright © 2012 John Wiley & Sons, Ltd.     

海上风力发电机组基础的选择

介绍了海上风力发电的发展现状,结合海上采油平台形式,对海上风电机组采用的基础定义、基础类型及其选择进行了介绍。     

新型铰接式海上风力机动力响应分析

文章针对75 m水深,开发了一种新型铰接式基础海上风力机,考虑到风浪流的联合作用,分析了其在发电海况和极限海况下的动力响应。基于叶素动量理论计算了风力机叶片气动载荷;基于经验公式计算了塔架风压载荷;基于三维势流理论计算了铰接式基础的水动力特性;考虑基础运动及波高引起的瞬时湿表面的变化及铰接点的结构阻尼,同时考虑海流力,编写程序计算风力机的时域动力响应特性。计算结果表明,铰接式海上风力机具有良好的运动性能,满足发电海况下正常发电的需求以及极限海况下结构自存的安全要求。     

近海风力机动力特性分析方法的研究

海上风力发电具有广阔的应用前景,因此要大力发展海上风机。以单桩式近海风力发电机为例,利用风机正向设计专业软件SAMCEF for Wind Turbine,对风机结构进行模态分析,得到结构的振动特性。由分析结果可知,风机整体振型复杂,不同构件振型变化较大,构件之间有连带作用;在系统的各阶振型中,每个构件的应变能贡献值各不相同,在设计风机时应避开结构的共振区域,以免造成风机结构的破坏。     

Feasibility study of offshore wind turbine substructures for southwest offshore wind farm project in Korea

Korea has huge potential for offshore wind energy and the first Korean offshore wind farm has been initiated off the southwest coast. With increasing water depth, different substructures of the offshore wind turbine, such as the jacket and multipile, are the increasing focus of attention because they appear to be cost-effective. However, these substructures are still in the early stages of development in the offshore wind industry. The aim of the present study was to design a suitable substructure, such as a jacket or multipile, to support a 5 MW wind turbine in 33 m deep water for the Korean Southwest Offshore Wind Farm. This study also aimed to compare the dynamic responses of different substructures including the monopile, jacket and multipile and evaluate their feasibility. We therefore performed an eigenanalysis and a coupled aero-hydro-servo-elastic simulation under deterministic and stochastic conditions in the environmental conditions in Korea. The results showed that the designed jacket and multipile substructures, together with the modified monopile, were well located at soft–stiff intervals, where most modern utility-scale wind turbine support structures are designed. The dynamic responses of the different substructures showed that of the three substructures, the performance of the jacket was very good. In addition, considering the simple configuration of the multipile, which results in lower manufacturing cost, this substructure can provide another possible solution for Korean’s first offshore wind farm. This study provides knowledge that can be applied for the deployment of large-scale offshore wind turbines in intermediate water depths in Korea.     

Simplified fatigue load assessment in offshore wind turbine structural analysis

The estimation of fatigue lifetime for an offshore wind turbine support structure requires a large number of time‐domain simulations. It is an important question whether it is possible to reduce the number of load cases while retaining a high level of accuracy of the results. We present a novel method for simplified fatigue load assessments based on statistical regression models that estimate fatigue damage during power production. The main idea is to predict the total fatigue damage only and not also the individual damage values for each load case. We demonstrate the method for a jacket‐type support structure. Reducing the number of simulated load cases from 21 to 3, the total fatigue damage estimate exhibited a maximum error of about 6% compared with the complete assessment. As a consequence, a significant amount of simulation time can be saved, in the order of a factor of seven. This quick fatigue assessment is especially interesting in the application of structural optimization, with a large number of iterations. Copyright © 2015 John Wiley & Sons, Ltd.     

Outlier robustness for wind turbine extrapolated extreme loads

Methods for extrapolating extreme loads to a 50 year probability of exceedance, which display robustness to the presence of outliers in simulated loads data set, are described. Case studies of isolated high extreme out‐of‐plane loads are discussed to emphasize their underlying physical reasons. Stochastic identification of numerical artifacts in simulated loads is demonstrated using the method of principal component analysis. The extrapolation methodology is made robust to outliers through a weighted loads approach, whereby the eigenvalues of the correlation matrix obtained using the loads with its dependencies is utilized to estimate a probability for the largest extreme load to occur at a specific mean wind speed. This inherently weights extreme loads that occur frequently within mean wind speed bins higher than isolated occurrences of extreme loads. Primarily, the results for the blade root out‐of‐plane loads are presented here as those extrapolated loads have shown wide variability in literature, but the method can be generalized to any other component load. The convergence of the 1 year extrapolated extreme blade root out‐of‐plane load with the number of turbulent wind samples used in the loads simulation is demonstrated and compared with published results. Further effects of varying wind inflow angles and shear exponent is brought out. Parametric fitting techniques that consider all extreme loads including ‘outliers’ are proposed, and the physical reasons that result in isolated high extreme loads are highlighted, including the effect of the wind turbine controls system. Copyright © 2011 John Wiley & Sons, Ltd.     

海上风力机的数值模拟

针对海上风力机运行的特点,根据NRELS809翼型数据,建立了水平轴风力机的整体模型。采用空气和水的两相流模型模拟海上工况,对模型进行数值计算,得到叶片绕流的速度分布和压力分布,并对两相流和单相流的变化情况进行了对比,最后对塔架的压力分布进行计算说明。研究结果表明:在两相流工况下,风轮叶片具有较高的功率系数,但该工况对叶片的强度、材料要求较高;气流流过叶片后均存在速度亏损,并在1倍风轮半径处趋于稳定;风轮对塔架的压力分布产生一定影响。