基于负荷侧响应的含储热热电联产的风电消纳模型

为了有效减少弃风,提高风电消纳能力,该文从负荷侧出发,通过峰谷分时电价策略引导用户的用电方式,达到削峰填谷,优化负荷曲线的目的.同时,在传统热电联产机组中应用大容量储热装置,通过对储热环节的控制,解耦以热定电约束,提高系统调节能力.以系统煤耗量最低为目标,构建包含储热的热电联产机组与风电联合出力优化调度模型.该模型...     

基于圆柱热源模型的现场测量地下岩土热物性方法

在埋地换热器圆柱热源模型的基础上采用参数估计法建立了一套可用于现场确定土壤热物性的方法。结合地源热泵系统单井热响应测试实验,计算了地下岩土热物性参数,模拟了管内流体平均温度随时间变化规律,与实验值比较,发现该方法较线热源法更加接近实际。     

WAVE PROPAGATION IN TWO-PHASE FLOW BASED ON A NEW HYPERBOLIC TWO-FLUID MODEL

A high-resolution up wind scheme based on the flux vector splitting method is developed for the two-fluid six-equation model to solve the wave propagation problems of two-phase flow. The interfacial pressure jump terms make the governing equations hyperbolic without any conventional source terms in the momentum equations. Real eigenvalues are obtained for all the bubbly, slug, and annular flow regimes. Calculated speeds of sound have shown excellent agreement with the existing experimental data. Solutions to wave propagation problems withinitial pressure and void distribution are presented. The Edwards pipe problem accompanied by sudden depressurization and flashing also is solved as a benchmark test.     

基于风速预测的风电场虚拟惯量协调控制技术

针对现有风电场虚拟惯量协调控制在风电机组调频辅助功率协调分配方面的研究,提出一种基于风速预测的风电场虚拟惯量响应场级协同分配策略,具体是通过经验模式分解（EMD）和BP神经网络训练风速时序序列获得风速时序模型,预测短时段内的风速,根据实时转速和预测风速计算惯量分配权重因子,根据频率变化计算全场惯量响应值,通过惯量分配权重因子结合变流器容量限值给单机分配惯量响应值。该控制策略成功应用于云南某148.5 MW风电场站级调频测试,验证了算法的有效性。     

基于转矩极限的改进风电机组虚拟惯量控制策略

为解决大规模风电并网带来的系统频率稳定性降低问题,风电机组通过虚拟惯量控制可为系统提供短期频率支撑,然而惯性响应期间风电机组转速收敛缓慢,导致一部分转子动能被无故浪费;转速恢复阶段的有功突变易造成频率二次跌落。为此,提出基于转矩极限的改进风电机组虚拟惯量控制策略,实现在释放较少动能的前提下提供与传统策略相同的频率响应服务;并在频率步入准稳态时,借助时变功率函数开始转速恢复,实现转速快速恢复的同时缓解二次频率跌落。基于EMTP-RV仿真软件搭建包含风电场的电力系统模型,验证了所提策略的有效性。     

基于改进型级联SOGI-FLL的虚拟惯量控制技术

阐述2种已有虚拟惯量控制算法:一种是基于二阶广义积分器-锁频环(SOGI-FLL)的虚拟惯量实现方法,其消除直流与特征次谐波扰动的能力有限;另一种是基于级联SOGI-FLL(CSOGI-FLL)的虚拟惯量实现方法,消除直流分量的干扰,但在消除特征次谐波扰动方面的能力也有限.为此,提出一种基于改进型CSOGI-FLL(I...     

基于图形逻辑分析的光伏储能系统能量管理方法

考虑现阶段市场普遍采用的峰谷分时阶梯电价机制,该文给出一种基于图形逻辑分析方法,以应用双向逆变器的光伏储能系统用户日用电消费最低为目的创新型能量管理方法。该方法通过分析每日用户用电量与光伏发电量,储能系统状态,结合现行电价与光伏补贴价格,设计光伏储能系统电能的合理流动及控制算法。利用电力公司的用户用电量、光伏发电量数据及上海市实际电价,验证该图形逻辑分析方法的有效性。计算表明在该方法控制下用户日用电消费明显降低;运算速度在相同仿真计算平台下,相比于普通寻优方法显著提高。     

PUBLICATIONS ON THERMAL STRESSES

In this paper we investigate mathematical models describing deformations and thermal variations of a thin homogeneous thermoviscoelastic plate. A hereditary non-Fourier constitutive law for the heat flux and some heat power constitutive equation with linear memory are considered. The resulting models are derived in the framework of the well-established theory, due to Gurtin and Pipkin, and according to the standard approximation procedure for the Reissner–Mindlin plate model.     

基于BP神经网络的热管式真空管集热器热性能预测校正模型

基于BP神经网络建立了热管式真空管集热器热性能的预测校正模型.该模型采用了LM和BR两种网络训练方法,经实验数据验证,预测校正模型输出结果的最大相对误差为2.8%,平均相对误差为1.2%,而数学模型输出结果的最大相对误差为6.2%,平均相对误差为4.3%,证明此预测校正模型的预测校正效果较好.应用该集热器热性能预测校正模型,可较精确地预测出不同运行状态、不同环境下集热器的出口温度,提高了系统的仿真精度.     

A NEW MODEL OF FUNCTIONALLY GRADED COATINGS WITH A CRACK UNDER THERMAL LOADING

A new model for fracture analysis oaf functionally graded materials (FGMs) with arbitrarily varying material properties under thermal loading is developed. The FGM is modeled as a multilayered medium and in each layer both shear modulus and thermal conductivity are assumed to be a linear function of the depth and are continuous on the subinterfaces. To make the crack problem tractable, thermal expansion and conductivity of the FGMs are supposed to have the same form. With this new model, the crack problem of a functionally graded coating bonded to a homogeneous substrate under steady-state thermal loading is investigated. Employment of the Fourier integral transform technique reduces the problem to a system of Cauchy singular integral equations that are solved numerically. Thermal stress intensity factors (TSIFs) are obtained for various forms of thermal conductivity or expansion. The results reveal that the present model is very efficient and in the frame of the present model both the form of thermal conductivity/expansion and that of its derivative can influence the TSIFs significantly.     

基于图像处理的建筑群室外热环境数学模型及实例分析

针对早期规划阶段的建筑群室外热环境问题,为建筑群空气流动建立了区域网络流动模型(即用建筑、地面等围成不同的流动区域),并通过各个流动区域的开口将这些流动区域连接起来构成网络模型;同时对建筑群中的建筑和地面建立了辐射、导热数学模型.在整体的数学模型中考虑了太阳直射、太阳散射、反射辐射、长波辐射、空气流动换热、建筑的外围护结构传热、地面传热等因素,分别以建筑、地面、空气为对象,建立热平衡方程进行耦合求解.同时,应用数字图像技术,实现了数字图像与建筑群室外热环境数学模型的结合.并通过实体建筑群的模拟分析和实测比较,验证了该模型的合理性.     

A THERMOMECHANICAL MODEL FOR THE ANALYSIS OF DISC BRAKE FRACTURE MECHANISMS

The aim of this article is to explain the damage mechanisms of disc brakes leading to macroscopic cracks on the friction surface. The work combines microanalysis of cracks and a thermomechanical modeling describing the thermal fatigue solicitation. The failure of disc brakes is discussed, giving indications of how to improve the design of this type of friction system in order to enhance its performances     

圆柱形相变蓄热器蓄/放热性能实验研究

设计并搭建了以太阳能为热源的圆柱形蓄热器实验台,将封装了相变材料(PCM)的蓄热球体放置在蓄热器中,测量蓄热器进出口和蓄热器内第一～七层的热媒(HTF)温度,对所测温度和流最进行数据采集.分析HTF的进口温度和流量变化对蓄热器热性能的影响.结果表明,随着HTF的进口温度的提高,完成蓄热所需的时间不断减少,蓄热效率得到提高,流速的增加对蓄热的影响不大.初步掌握热媒的流动特性对相变蓄热装置蓄放热过程的影响,为蓄热器的工程应用设计、评价提供参考依据.     

基于太阳能利用的相变蓄热水箱结构优化

为解决因太阳能的不稳定性等因素导致的太阳能蓄热水箱储热/放热能力的不保证性问题,提出采用中低温有机相变材料58号石蜡作为相变蓄热材料的圆台式太阳能相变蓄热水箱。采用计算流体力学(computational fluid dynamics,CFD)数值模拟的计算方法,在保证总蓄水体积(以100 L为例)不变的情况下,对水箱中不同内胆倾斜角度分别为75°、80°、85°、90°、95°、100°、105°的放热过程进行数值模拟,综合对比和分析水箱放热性能模拟结果,得到当倾斜角度为105°时的相变蓄热构件放热性能最佳,可为太阳能相变蓄热水箱的结构优化设计提供理论依据。     

A SIMPLIFIED CONJUGATE-GRADIENT METHOD FOR SHAPE IDENTIFICATION BASED ON THERMAL DATA

The present study is focused on simplification of the conjugate-gradient method so as to extend the flexibility of the inverse heat transfer method for applications in the shape identification problems associated with various forms of objective functions. The capability of the simplified conjugate-gradient method (SCGM) in seeking the shapes of inner structures is tested for several cases. These test cases use three kinds of thermal data measured on the outer surface of a solid body, including temperature distribution, local heat flux distribution, and the overall heat transfer rate. The aim of these test cases is to identify the boundary of the inner voids in the solid bodies based on the thermal data. Results show that for all test cases, the optimization process leads to acceptable accuracy for the objective functions of different forms.     

基于多时间尺度的并网型风力发电机组模型

对采用异步发电机与电网直接相连的风力发电机组进行了建模,并利用多时间尺度系统理论对模型进行了简化,采用仿真方法验证了简化后的模型的有效性。此外,还对整个风力发电系统的运行方式,补偿电容的动态作用进行了详细的分析,说明了此种风电机组的优缺点。     

A WIND-POWER FORECAST SYSTEM BASED ON THE METEOROLOGICAL NUMERICAL MODEL

基于高分辨率中尺度气象模式,利用卡尔曼滤波订正技术和经验统计规律订正技术,通过动态加入实时观测资料对数值模式预报风速进行滚动订正,建立基于气象数值模式的风电功率预测系统,开展风电场未来72h风速及风电功率预测.利用该系统在上海崇明风电场进行为期两个月的预报试验,结果表明:数值模式预报风速与观测值之间的误差随着预报时效增长逐渐加大,并在不同时段模式的系统误差分布规律也有所差别,模式预报风速与误差之间有一定的统计关系.经过滚动订正预报模型订正后,预报发电量误差比模式本身预报发电量误差明显减小,风速及发电功率预报质量明显提高.     

一种基于新结构的线性腔式太阳能集热器研究

提出一种适用于槽式太阳能热发电系统的新型线性腔式集热器.通过Tracepro模拟聚光镜焦距、弧形结构及开口宽度对系统光学性能的影响;采用热网络模型对该集热器的传热性能进行参数化研究,确定优化的集热器结构为优弧型,开口宽度为70 mm,与其匹配的聚光镜焦距为2100 mm.研究结果表明,当太阳直射辐射强度为500 W/m...     

THERMAL MODELLING OF MULTIPASS AIR HEATER

In this communication, an analysis of multipass air heating system has been carried out bv incorporating the effect of reflector, duct length, thermal storage and movable insulation for various applications. The analysis is based on energy balance equations for different component of the system. In order to have the parametric study, numerical computation has been done for a typical day of the month of June and December for Delhi climatic conditions. It has been observed that design parameters can be optimized by the proposed theory     

A NEW HIGH-RESOLUTION SCHEME BASED ON THE NORMALIZED VARIABLE FORMULATION

Abstract

A high-resolution (HR) discretization scheme is proposed for the calculation of incompressible steady-state convective flow with finite-volume methods. The basic algorithm combines a second- and third-order interpolation profile applied in the context of the normalized variable formulation (NVF). The new scheme is tested by solving three problems: (1) a two-dimensional pure convection of a scalar involving a step profile in an oblique velocity field; (2) a two-dimensional pure convection of a scalar involving an elliptic profile in an oblique velocity field; (3) the Smith-Hutton [1] problem involving pure convection of a step profile in a rotational velocity field. The computational results obtained are compared with the results of six HR schemes: Leonard's EVLER scheme, Gaskell and Lau's SMART scheme, Van Leer's CLAM and MUSCL schemes, Chakravarthy and Osher's OSHLR scheme, Roe's M1NMOD scheme, and the exact solution. The results for the new scheme, STOIC demonstrate its capability in capturing steep gradients while maintaining the boundedness of solutions. Furthermore, the comparison with other HR schemes shows that the STOIC scheme yields the most accurate results without undue physical oscillations or numerical smearing