大型失速型风力机组的建模与仿真

建立了大型失速型风力发电机组在标称状况下的非线性数学模型，将其线性化后，在不同风速下进行了不同输入，（风速Ｖ和电网电压Ｕ１变化）条件下的开环仿真，仿真结果对控制器的设计有参考价值。     

不同风况和系统容量下双馈风机并网谐波特性研究

以变速恒频双馈风力发电系统为研究对象,基于MATLAB搭建了全系统仿真模型,重点构建了风速的四分量仿真模型,并且针对风电系统在不同的风速分量模型下和不同系统容量下的谐波特性进行了仿真研究,定量地得出了双馈风力发电系统并网的谐波特性。     

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。     

基于瑞利概率分布的风力发电系统中组合风速的改进及建模仿真

风速作为风力发电机组的输入信号,其模拟的正确性直接影响着整个风力发电系统的性能分析与研究。通常计算机仿真所得风速是通过对不同风速的简单组合而实现的某个地区及时间段的平均风速,仿真风速无法体现自然风的多样性。针对此问题,文章提出一种实现自然风的方法。依据某风电场风资源评估报告所给出的风频分布曲线,以瑞利分布规律随机配置各种风速信号,在Matlab/Simulink的运行环境下,仿真出改进的风速,使不同风速随机分配,并且在某个时间段内各种风速出现的概率符合瑞利概率分布。据此方法所得风速更加接近实际自然风,且涵盖从切入风速到切出风速范围内所有风速类型,对风力发电系统的性能分析与研究具有一定的实际意义。     

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     

基于结构优化的聚风装置流场特性数值研究

INVELOX风能发电是一种管道式风能采集系统,该系统可在多方向和低风速下获取风能,系统效率取决于来流风速和文丘里管平均风速的比值,即流速比SR。文章基于INVELOX系统进行模型优化,设计了一种小型风能采集装置,使用基于格子玻尔兹曼方法（LBM）的流体力学计算软件XFlow对该装置在不同风速下的流场特性进行数值模拟,通过计算文丘里管内SR比值,得出其临界工作风速为3 m/s。通过对V-SR图分析可知,随着流场风速的增大,该装置对环境中风速的增强作用随之增强。考虑现实环境的应用情况,以6 m/s作为流场风速,对水平和倾斜来流风向下的INVELOX系统进行了仿真分析,得到不同攻角下文丘里管内工作段风速变化情况,为此类能源采集装置的工程应用提供参考。     

5MW风力机地震工况塔架动力学响应研究

基于FAST开源软件和Wolf土-构耦合(SSI)模型建立了风力机地震工况动力学仿真模型,并计算了5种不同平均风速的气动载荷与101种不同强度的地震载荷联合作用下风力机的动力学响应.结果表明:在额定风速下,气动载荷与地震载荷之间为非线性耦合,评估风力机地震动力学响应时,必须充分考虑风-震耦合效应;风速相同时,塔基最大弯矩先保持不变,再以线性增长的趋势变化;在低强度地震时,塔架不同高度处的最大弯矩与塔架高度之间为线性关系;随着地震强度的逐渐增大,塔架最大弯矩与塔架高度之间的关系逐渐变为非线性,且额定风速下塔架最大弯矩最大.     

基于复合传动原理的并网型风电机组调速系统设计

设计一种适用于并网型风电机组的复合调速传动系统。该变速装置直接与风轮转子连接,通过调节液力变矩器的涡轮输出速度,液力调速传动系统可实现在不同的风速下的恒转速输出,从而实现无需增速齿轮箱和变频器的发电机恒频输出。建立所设计的液力调速传动系统SIMULINK模型,并采用美国国家可再生能源实验室(National Renewable Energy Laboratory)的FAST(Fatigue,Aerodynamics,Structures and Turbulence)软件模拟不同风速下1.5MW风力发电机的工作情况。通过FAST和SIMULINK仿真试验,在不同风速条件下,验证设计的液力变速传动系统。     

羽绒流化干燥特性的实验研究

在实验台上，首先对干羽绒进行了流化实验，得到了羽绒干态的流化特性，确定了空床流化风速和携带风速；在此基础上，对湿羽绒进行了流化干燥实验，得到了在不同进口风温、不同流化速度和不同物料量下的动态干燥特性，确定了最佳的干燥风温和流化风速，为羽绒流化干燥系统的设计提供了实验依据。     

基于Matlab/Simulink的风力机性能仿真研究

随着风力发电技术的发展，变速风力发电技术成为了风力发电发展的趋势。风力机作为变速风力发电机组的重要部分，其性能影响到风力发电机组的整体性能。根据变速风力机的静态性能特点，采用Matlab／Simulink软件对其进行建模，并给变速风力发电机组风力机输入模拟变速风速进行仿真研究，给出了风力机的静态性能数据和仿真波形。结果表明：通过调节影响风力机性能的各因素，保持发电机的转速与主导风速之间特定的最优比例系数，使得风力机保持在最佳叶尖速比下运行，跟随变速风速可实现最大风能捕获；对变速风力机的静态性能研究建模方法是正确可行的。     

抽水蓄能电站机组异常状态检测模型研究

针对当前水电机组故障样本少,难以对其开展有效诊断的难题,提出了一种综合考虑有功功率、工作水头等工况参数的基于最小二乘曲面的抽水蓄能电站机组异常状态检测模型,即在深入分析有功功率、工作水头对机组运行状态影响的基础上,确定了机组的健康标准状态,根据机组运行状态在不同功率和不同水头下的特性,划分了不同单元,在不同单元内选取能反映机组运行状态的敏感特征参数,分别建立了基于最小二乘曲面的分布式健康模型,将功率、水头等实时在线数据代入分布式健康模型,通过计算机组健康度建立最终的异常状态检测模型。实例应用结果表明,该模型能有效地挖掘机组海量状态数据和真实可靠地进行在线状态评估,从而实现机组异常状态的早期预警。     

Effect of compression on pore size distribution and porosity of PEM fuel cell catalyst layers

In this study, effects of compression (up to 5 MPa) on pore size distribution (PSD) and porosity of catalyst layers (CL) are investigated using a developed model for deformation of CL under compression. The model is based on effective medium theory and uses a representative geometry (unit cell) to simplify the complex and random porous structure of CL. In this model, different sizes are found for unit cells which are based on CL PSD measurement; this means that unit cell size has distribution since PSD is used as an input to the model. The model has been validated with experimental data in our previous publications. Effect of compression on four different CL samples is studied using the developed model and change of pore diameter is found as function of compression. The change of pore size is different for each sample and dependents on CL initial porosity, PSD, and ink properties. PSD and porosity, which are the indications of microstructure of CL, are found after compression up to 5 MPa. Larger pores show the most change, which causes the void volume percentage of smaller pores to increase, even though the number of pores remain the same. It is also found that the diameter of secondary pores can be decreased by up to 50% depending on CL microstructure, which is significant.     

Effects of different multiple PCMs on the performance of a latent thermal energy storage system

The present study presents a theoretical model for the performance of a shell and tube latent thermal energy storage (LTES) unit using multiple phase change materials (PCMs). The model is based on the enthalpy method. Numerical simulations are carried out to investigate the effects of different multiple PCMs on the melted fraction, stored thermal energy and fluid outlet temperature of the LTES unit. Numerical results indicate that PCMs’ fractions and melting temperatures play an important role in the performance of the LTES unit. As a result, appropriate choosing of multiple PCMs is very significant for the performance improvement of the LTES unit.     

A FULLY COUPLED THERMO-MECHANICAL MICROMECHANICS MODEL

The development for a micromechanical model with full thermomechanical coupling, which is based on the combined effects of the mechanical and energy equations, is presented. The model is based on a combined approximate kinematic and thermal analysis of a repeating unit cell in a triply periodic array of inclusions. The unit cell is considered to consist of different subregions that can be composed of any desired material. The behavior of the material within the different subregions can be modeled using elastic, plastic, viscoelastic, viscoplastic, or damage constitutive models. The analysis satisfies the equations of motion and the energy equation for the different subregions of the unit cell in an average sense. The interfacial continuity conditions for the velocities, stresses, temperature, and thermal fluxes between the different subregions are also satisfied in an average sense. Arbitrary heat source terms are included in the energy equation to allow for the analysis of reactive materials. The resulting system of governing equations exhibits full coupling between the deformations and the thermal effects. The proposed model is analytical and provides closed-form expressions for the effective macroscopic kinematic and thermal behavior of a particulate composite. The influence of the thermomechanical coupling on behavior at both the macroscopic and microscopic levels is considered. The presence of the coupling can lead to significant localization of the thermal and deformation responses within different regions of the unit cell. It is shown that the presence of inelastic deformations in conjunction with thermomechanical coupling effects can result in appreciable deviation from an isothermal, inelastic analysis.     

风冷热泵冬季运行模拟与理论计算

建立了风冷热泵冬季运行状态下基于气液分相的集中参数模型。在模型中不仅对蒸发器干工况和结露工况作了数学描述,同时还分析了结霜过程中霜层密度和厚度变化对机组性能的影响,基于这一模型。选择某种热泵进行了计算,得到了这种上机组在不同温湿度和进出水温度下机组的能效比和结霜性能。     

加热器散热损失对机组热经济性的影响

基于热平衡方程,提出了加热器散热损失对机组热经济性影响的计算模型。该模型采用矩阵形式,全面考虑了热力系统的结构特点和辅助汽水系统,计算快速、精确,并且该模型通用性强,适用于各种凝汽机组。应用该模型对某300 MW机组进行了算例分析,并同等效热降法进行比较,总结出了加热器散热影响机组热经济性的主要因素,这将在电厂运行及节能工作中发挥重要作用。     

A novel business model for aggregating the values of electricity storage

Electricity storage is considered as a valuable source of flexibility with applications covering the whole electricity value chain. Most of the existing evaluation methods for electricity storage are conceived for one specific use of the storage, which often leads to the conclusion that the investment on storage does not pay off. However, the value of storage cannot be properly estimated without taking into account the possibility of aggregating the services that storage can offer to different actors. This paper proposes a new business model that allows aggregating multiple revenue streams of electricity storage in a systematic way. The model consists in coordinating a series of auctions in which the right to utilize the storage unit is auctioned upon different time horizons. In the mean time, non-conflicting usage of storage by the actors in these different auctions is ensured. The functioning of the model is demonstrated by a case study. The results show that a storage unit can achieve higher return on investment in the manner proposed in the business model.     

An all-condition simulation model of the steam turbine system for a 600 MW generation unit

Coal-fired generation units in China often operate under off-design loads. The off-design performance has important influence on operation energy consumption of generation units. An all-condition model is of critical importance for studying the off-design performance. In this paper, an all-condition simulation model of the steam turbine system for a 600 MW generation unit is built. Based on the actual system composition, the steam turbine system is divided into several sub equipment. A sub model is established for each device. In the turbine model, a parameter M is defined as the intermediate variable to calculate the extraction pressure of turbine. The operating data from a 600 MW generation unit are used to verify the all-condition model. The heater fouling conditions are also calculated. The result shows that the model successfully predicts the operation parameters under different loads and forecasts the thermal performance of typical equipment failure.     

主蒸汽压力变化对机组煤耗率的影响分析

主蒸汽压力是机组实际运行中必须密切监视和调节的主要参数之一,在机组实际运行中会不可避免的偏离设计值,从而影响机组的发电标准煤耗率,影响机组的热经济性和安全性.在火电厂热经济性统一物理模型和数学模型的基础上,根据多元扰动下的热力系统能效分析模型得到主汽压变化对煤耗率影响的计算模型,并以某电厂660 MW机组为例进行验证,并计算了此机组不同工况下主汽压变化对机组煤耗的影响,并绘制成图,对其规律进行了分析.此计算模型得到的计算结果误差较小,足以满足工程实际的需要.     

基于分支限界法的火电机组负荷分配研究

针对大规模新能源并网调峰问题,提出不同调峰阶段火电机组负荷分配方法：分析火电机组调峰能力、调峰成本及二者之间的关系;以总煤耗成本、机组启停成本之和最小为目标,建立不同调峰阶段火电机组负荷分配优化模型;根据火电机组爬坡率、滑坡率,提出参与负荷分配机组的组合策略,并使用分支限界法对负荷分配优化模型求解。算例表明,随着火电机组调峰深度的增加,机组煤耗成本和启停成本减少,深度调峰运行下附加煤耗成本和机组损耗成本增加。