风力发电系统中组合风速的建模及仿真

在实验室进行风力发电系统模拟,风速模拟是其中重要的一个环节,正确的风速模型不仅可以反应风速实际变化情况,而且能给风力发电系统的模拟研究提供准确的参数。文章采用4分量组合风速模型,用Matlab/Simulink对组合风速进行建模仿真。仿真结果表明,该数学模型能够较精确地反映风速的实际突变性、渐变性及随机性等特点,适用于风力发电系统的模拟研究工作。     

基于威布尔分布的风速概率分布参数估计方法

准确地描述风速特性,直接影响风电场风能资源评估的结果.文章介绍了基于威布尔分布的平均风速及最大风速估计法、矩估计法、最小二乘估计法和极大似然估计法等4种风速概率分布参数估计的方法.通过对乌兰察布地区测风塔实际数据的分析,比较了4种方法的参数估计结果,得到以下结论:在风能资源较丰富地区,平均风速及最大风速估计法的风速拟合效果波动较大,对平均风能密度估计误差较大;矩估计法、最小二乘估计法和极大似然估计法拟合效果良好.     

基于零维模型的柴油机建模与仿真

通过对柴油机缸内热力工作过程的分析,建立了柴油机的Matlab/Simulink零维仿真模犁,并将其计算结果与发动机热力性能分析软件AVL Boost的计算结果进行对比,结果表明,该模型对四冲程增压柴油机的仿真计算具有较高的精度,验证了模型的正确性。     

基于BP神经网络方法的风电场风速插补分析应用

[目的]准确的风资源数据对风场的风资源评估和发电量计算有着重大意义.由于机械故障、天气因素和人为影响等原因,风场内风速数据出现采集时间短、间断点多、数据失真等诸多问题,给风资源的评估带来不小的麻烦.[方法]现阶段风电行业内采用基于相关测量预测方法(MCP,Measure-Correlate Predict)(可称之为传...     

海陵岛区域风速廓线特性及利用模式进行沿海风能评估过程中风速廓线的作用

通过对广东省阳江市海陵岛地区为期一年的铁塔观测资料进行分析,发现当风向为海风风向和陆风风向时,当地的风速廓线有很大差异,陆风风向阶段风随高度的切变较大,而海风风向阶段切变较小.因此在利用模式进行近海风能评估时,若能较好的利用风速廓线的性质,将大大提高近海风能评估的精确性,弥补观测资料不足所带来的缺憾.     

基于Saber的风力发电系统建模及仿真分析

采用专业软件Saber,结合MAST语言的编写,搭建了直驱式变速恒频风力发电系统的主电路模型和控制电路模型,并对该模型进行了仿真分析,分析结果说明了直驱式变速恒频风力发电系统的良好运行特性.另外,建模中根据仿真时间及仿真速度的要求,基于开关周期远小于仿真时间以及输出滤波器设计较好的假设,可在一定条件下忽略电力电子系统中开关作用的影响,建立该系统的平均模型,给出数值仿真结果,其仿真结果之间的比较验证了平均模型的可行性及有效性.     

离网小型风力发电系统的建模与仿真

在Matlab/simulink环境下建立了离网小型风力发电系统仿真模型,通过对风速和系统各部分进行理论分析,实现整体模型的搭建。仿真结果表明,在铅酸蓄电池作用下,系统能在变化风速下持续稳定运行,负载端电压符合用户要求     

风电泵系统的仿真研究

介绍了基于MATLAB/Simulink的风电泵系统仿真.首先给出风电泵系统的数学模型.然后采用Simulink建立系统的仿真模型并进行仿真和分析.通过仿真得到了电机的重要参数(电枢电阻、磁场强度)和离心泵对风电泵系统的影响,并且简单地分析出引起这些变化的原因.此仿真可为风电泵各部件参数匹配提供依据.     

基于Matlab/Simulink的火电厂热力系统模块化建模方法

本文以常规热平衡法为基础,引入模块建模的思想,阐述了模块化建模的开发过程,提出了一种火电厂热力系统模块化建模的方法。通过对热力系统分解、模块化,Matlab／Simulink为开发工具建立了火电厂常用设备的模型库,并给出实例验证了所提方法的正确性和可行性。     

基于Matlab/Simulink的有机朗肯循环发电系统建模与仿真

以某型微燃机排出的尾气作为热源,根据热源特性和热力学基本原理,选择了环戊烷(Cyclopentane)作为循环工质,建立了整个有机朗肯循环发电系统的热力学模型,并通过M atlab/Simulink软件平台分别建立系统各部件的仿真模块,实现了有机朗肯循环发电系统的动态仿真。仿真结果表明:输入热源温度在100~300℃内,选用环戊烷作为循环工质是合理的,窄点温度及排气温度均在合理的范围内,与实际工况要求吻合;而热源温度高于300℃时,环戊烷工质则不能适应,需要对输入热源降温处理;当热源温度低于100℃时,ORC发电系统已无法正常输出有效功,系统无法正常循环运行。文中仿真分析可以为ORC系统的优化设计及实验研究提供参考。     

基于风速Weibull分布的电力系统备用容量优化模型

为了解决风电功率的随机波动和预测精度不高对风电并网的影响,引入风速Weibull概率分布函数和风功率概率分布函数,建立了基于风速概率分布的长期经济调度模型。该模型考虑长期调度和风电功率概率分布,在计算备用时不需考虑风电功率的时序性,这样使得模型得到了简化。最后通过算例仿真,讨论了该模型对系统备用容量和风电场成本的影响,同时验证了该模型的可行性。     

Assessing the suitability of wind speed probabilty distribution functions based on wind power density

Three functions have so far predominantly been used for fitting the measured wind speed probability distribution in a given location over a certain period of time, typically monthly or yearly. In the literature, it is common to fit these functions to compare which one fits the measured distribution best in a particular location. During this comparison process, parameters on which the suitability of the fit is judged are required. The parameters that are mostly used are the mean wind speed or the total wind energy output (primary parameters). It is, however, shown in the present study that one cannot judge the suitability of the functions based on the primary parameters alone. Additional parameters (secondary parameters) that complete the primary parameters are required to have a complete assessment of the fit, such as the discrepancy between the measured and fitted distributions, both for the wind speed and wind energy (that is the standard deviation of wind speed and wind energy distributions). Therefore, the secondary statistical parameters have to be known as well as the primary ones to make a judgement about the suitability of the distribution functions analysed. The primary and secondary parameters are calculated from the 12-month of measured hourly wind speed data and detailed analyses of wind speed distributions are undertaken in the present article.     

A combined wind and hydro power system

A high degree of coverage of electricity demand by wind energy conversion is possible only with access to energy storage. For regions with both hydro and wind resources, the hydro power system and the wind power system may complement each other and alleviate the need for any other energy storage. Scandinavia is such a region, and this article uses a simulation model to assess the conditions under which all the electricity needs of Norway and Denmark could be satisfied by a combination of the existing Norwegian hydro power system with a hypothetical all wind-based Danish power system.     

基于PSCAD的并网型风机建模及仿真

建立了包含风速模型、风力机模型、发电机模型和控制系统模型的风力发电机组的整体动态数学模型;应用PSCAD软件,以建立的数学模型为基础搭建了变速恒频风电机组仿真算例;并以短路故障和渐变风干扰为例,对由一台单机容量为2 MW变速恒频风电机组并网后的运行特性进行了仿真研究.仿真结果表明了变速恒频风电机组良好的运行特性及影响该机型风机稳定的因素.     

Using nacelle‐based wind speed observations to improve power curve modeling for wind power forecasting

Wind power forecasting for projection times of 0–48 h can have a particular value in facilitating the integration of wind power into power systems. Accurate observations of the wind speed received by wind turbines are important inputs for some of the most useful methods for making such forecasts. In particular, they are used to derive power curves relating wind speeds to wind power production. By using power curve modeling, this paper compares two types of wind speed observations typically available at wind farms: the wind speed and wind direction measurements at the nacelles of the wind turbines and those at one or more on‐site meteorological masts (met masts). For the three Australian wind farms studied in this project, the results favor the nacelle‐based observations despite the inherent interference from the nacelle and the blades and despite calibration corrections to the met mast observations. This trend was found to be stronger for wind farm sites with more complex terrain. In addition, a numerical weather prediction (NWP) system was used to show that, for the wind farms studied, smaller single time‐series forecast errors can be achieved with the average wind speed from the nacelle‐based observations. This suggests that the nacelle‐average observations are more representative of the wind behavior predicted by an NWP system than the met mast observations. Also, when using an NWP system to predict wind farm power production, it suggests the use of a wind farm power curve based on nacelle‐average observations instead of met mast observations. Further, it suggests that historical and real‐time nacelle‐average observations should be calculated for large wind farms and used in wind power forecasting. Copyright © 2011 John Wiley & Sons, Ltd.     

复杂地形对风速分布影响的数值模拟研究

以Askervein山为研究对象,采用计算流体力学(CFD)方法对其风场进行数值模拟研究并与实验数据进行了比较,验证数值方法的可靠性,同时对山顶垂直风速分布进行了分析。结果显示在迎风坡和背风坡其模拟结果具有很高的吻合度,而山顶风速与实测值误差较大。     

Analysing wind power ramp events and improving very short-term wind power predictions by including wind speed observations

Though wind power predictions have been consistently improved in the last decade, persistent reasons for remaining uncertainties are sudden large changes in wind speed, so-called ramps. Here, we analyse the occurrence of ramp events in a wind farm in Eastern Germany and the performance of a wind power prediction tool in forecasting these events for forecasting horizons of 15 and 30 min. Results on the seasonality of ramp events and their diurnal cycle are presented for multiple ramp definition thresholds. Ramps were found to be most frequent in March and April and least frequent in November and December. For the analysis, the wind power prediction tool is fed by different wind velocity forecast products, for example, numerical weather prediction (NWP) model and measurement data. It is shown that including observational wind speed data for very short-term wind power forecasts improves the performance of the power prediction tool compared to the NWP reference, both in terms of ramp detection and in decreasing the mean absolute error between predicted and generated wind power. This improvement is enhanced during ramp events, highlighting the importance of wind observations for very short-term wind power prediction.     

Simulation of hourly wind speed and array wind power

Statistical summaries of wind speed are sufficient to compute many characteristics of turbine-generated power, such as the mean, variance and reliability of various power levels. However, a wind speed time series is necessary to produce a sequence of power values as used for investigating load matching and storage requirements. Since a long historical record of wind speed may not be available at a wind turbine candidate site, it is desirable to be able to generate a simulated numerical sequence of hourly wind speed values. Two such approximate procedures are developed in this paper. One procedure generates sequential wind speed values at a site based on the Weibull parameters of hourly wind speed and the lag-one autocorrelation of hourly wind speed values. Comparison with historical data at a site is made. The second procedure generates sequential hourly wind power values for a regional array of wind turbines. It utilizes the typical site wind characteristics, the spatial and lag-one cross correlation and autocorrelation of hourly wind speed values and an equivalent linearized relationship between array average wind speed and array power. Comparison with results for six different wind turbines in three different regional arrays indicates good agreement for wind power histograms, autocorrelation function and mean persistence.     

基于Matlab的含风电电网建模与仿真

介绍了应用Matlab 7.0对含风电的电网建模以及风速突然变化、系统电压突然下降和电网发生单相接地短路3种情况的仿真分析方法和机理。仿真结果表明，变速风力机驱动双馈式异步风力发电机组的变速平稳。机组效率高，对电网也可以起到一定的稳压和无功调解的作用。