Equivalent Method of Integrated Power Generation System of Wind, Photovoltaic and Energy Storage in Power Flow Calculation and Transient Simulation

针对工程实际开展风光储联合发电系统在潮流计算和机电暂态仿真中的等值方法研究，旨在为大容量风光储联合发电系统的并网仿真分析奠定基础。将潮流计算的等值分为单元机组和集电系统2部分来研究。单元机组等值采用根据不同控制模式选取不同节点类型的方法，针对集电系统等值提出基于损耗不变原则的方法。等值模型和详细模型的算例结果表明，潮流计算等值方法具有较好的精度。在机电暂态仿真动态等值中，基于实际工程计算的最严重工况分析原则，提出运行在满出力点的单机“倍乘”等值模型，为工程计算中的风光储联合发电系统动态等值提供了一种解决方案。

Calculating Method for Influence of Material Flow on Energy Consumption in Steel Manufacturing Process

From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship between material flow and the energy intensity is useful to save energy in steel industry. Based on the concept of standard material flow diagram, all possible situations of ferric material flow in steel manufacturing process are analyzed. The expressions of the influence of material flow deviated from standard material flow diagram on energy consumption are put forward.

THE NONLINEAR STABILITY OF PLANE PARALLEL SHEAR FLOWS WITH RESPECT TO TILTED PERTURBATIONS

The nonlinear stability of plane parallel shear flows with respect to tilted perturbations is studied by energy methods.Tilted perturbation refers to the fact that perturbations form an angleθ∈(0,π/2)with the direction of the basic flows.By defining an energy functional,it is proven that plane parallel shear flows are unconditionally nonlinearly exponentially stable for tilted streamwise perturbation when the Reynolds number is below a certain critical value and the boundary conditions are either rigid or stress-free.In the case of stress-free boundaries,by taking advantage of the poloidal-toroidal decomposition of a solenoidal field to define energy functionals,it can be even shown that plane parallel shear flows are unconditionally nonlinearly exponentially stable for all Reynolds numbers,where the tilted perturbation can be either spanwise or streamwise.

Phase transition model of water flow irradiated by high-energy laser in a chamber

In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study＇s results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow.

Design of Poiseuille Flow Controllers Using the Method of Inequalities

This paper investigates the use of the method of inequalities （MoI） to design output-feedback compensators for the problem of the control of instabilities in a laminar plane Poiseuille flow. In common with many flows, the dynamics of streamwise vortices in plane Poiseuille flow are very non-normal. Consequently, small perturbations grow rapidly with a large transient that may trigger nonlinearities and lead to turbulence even though such perturbations would, in a linear flow model, eventually decay. Such a system can be described as a conditionally linear system. The sensitivity is measured using the maximum transient energy growth, which is widely used in the fluid dynamics community. The paper considers two approaches. In the first approach, the MoI is used to design low-order proportional and proportional-integral （PI） controllers. In the second one, the MoI is combined with McFarlane and Glover＇s H∞ loop-shaping design procedure in a mixed-optimization approach.

Electrokinetic flow and energy conversion in a curved microtube

Curved channels are ubiquitous in microfluidic systems.The pressure-driven electrokinetic flow and energy conversion in a curved microtube are investigated analytically by using a perturbation analysis method under the assumptions of the small curvature ratio and the Reynolds number.The results indicate that the curvature of the microtube leads to a skewed pattern in the distribution of the electrical double layer(EDL)potential.The EDL potential at the outer side of the bend is larger than that at the inner side of the bend.The curvature shows an inhibitory effect on the magnitude of the streaming potential field induced by the pressure-driven flow.Since the spanwise pressure gradient is dominant over the inertial force,the resulting axial velocity profile is skewed into the inner region of the curved channel.Furthermore,the flow rate in a curved microtube could be larger than that in a straight one with the same pressure gradient and shape of cross section.The asymptotic solutions of the axial velocity and flow rate in the absence of the electrokinetic effect are in agreement with the classical results for low Reynolds number flows.Remarkably,the curved geometry could be beneficial to improving the electrokinetic energy conversion(EKEC)efficiency.

Establishment of the "Fenlong Energy Theory" and Conjecture of the "Fenlong Dark Matter Flow"

It is the first time that the world’s first new method of farming,the"Fenlong farming technology,"has been systematically clarified,and the"Fenlong body integrating with natural science"has been created in terms of land resource activation,natural fertilization,natural water management,natural ecological improvement(including climate),and natural indirect activation of river water resources.Moreover,the"theory of Fenlong energy"has been established based on its effectiveness.The"theory of Fenlong energy"originates from the"multiplying and incremental utilization of three-dimensional spatial resources"in production practice.Its application to more than 40 kinds of crops such as rice,corn and wheat in 26 provinces including Guangxi,Xinjiang and Tibet shows that:the yield of arable land increases by 20%to 50%(the quality is improved by 5%),the yield of saline land increases by 20%to 100%,and it can retain 100%of water and resist or ease the disaster.The"theory of three-dimensional spatial resources","Fenlong science","Fenlong law"are the theoretical base for the establishment of the"theory of Fenlong energy".Based on the phenomena that the Fenlong crops have particularly developed root systems,white and more fibrous roots,and tall plants,it is proposed for the first time that Fenlong farming breaks the confinement of the bottom layer of the plow and realizes the holographic penetration of material,energy,and information flows,and there may be the speculation of"Fenlong dark matter flow".

考虑碳排放分摊的综合能源服务商交易策略

为寻求在满足用户用能需求的同时降低系统碳排放的有效途径,提出了一种考虑碳排放分摊的多综合能源服务商能源交易策略。基于网络流模型实现碳流追踪并联合Shapley理论建立了综合能源服务商碳排放成本计算模型。应用Nash议价理论构建了多综合能源服务商合作博弈运行模型,将综合能源服务商碳排放成本引入优化目标函数,并利用分布式算法求解最优能源交易量和交易费用。基于由修改的IEEE 39节点电网和12节点气网构成的多综合能源服务商系统进行仿真分析,验证了所提模型和方法的有效性。

基于功率流有限元法的涡旋压缩机振动特性研究

针对涡旋压缩机内部振动传递路径复杂,采用传统的传递函数法往往不能真实地描述振动产生与传递的本质问题,引入功率流有限元法从能量角度分析振动传递特性,进行涡旋压缩机内部振动产生、传递与空间分布的可视化研究。在分析涡旋压缩机的动力拓扑关系基础上建立激励源,提取与振动响应模型并进行仿真分析;利用实体试验和响应分析结果对比进行模型有效性分析;在验证后的模型上定义8个能量输出面,分析谐波与激励作用下上支撑和下支撑的振动能量传递特性,并且计算节点的功率流矢量确定振源的空间分布。结果表明,涡旋压缩机曲轴在运转到280°时,振动频率在1 000 Hz与1 890 Hz时振动能量传递率较高,上支撑能量分布均匀并集于自身,下支撑能量集中于支脚并向外传递。研究方法和研究成果对于涡旋压缩机振动分布及传递、振动控制和优化设计等方面具有一定借鉴意义。

综合能源系统建模与仿真:综述、思考与展望

建模和仿真将真实系统及其物理性质抽象化为适当的数学形式,并采用数学方法求解以模拟真实系统行为或性能。为综合能源系统在各时间尺度的物理过程建立恰当的数学模型并进行仿真验证,是分析系统运行规律、优化运行策略以及评估运行性能的基础。文中围绕电气热综合能源系统建模和仿真问题,首先介绍了电、气、热子系统和耦合设备的机理模型,总结了建模的研究进展与技术难点。进一步,从仿真框架、算法以及改进策略3个方面介绍了综合能源系统仿真技术所取得的研究进展。特别地,总结了仿真算法中数值法、半解析法、解析法的原理、应用现状及其难点。最后,围绕现存技术难点,从建模和仿真算法2个方面对未来研究进行了展望。

电-气互联系统仿射能流交替递归计算方法

在源荷不确定性日益显著的背景下,不确定性能流计算对电-气互联系统能源优化调度具有重要意义。针对天然气网络仿射能流算法面临的仿射数矩阵求逆运算复杂、难以适用环网等问题,该文提出一种天然气网络全纯嵌入仿射能流方法。在此基础上,根据耦合设备处的能量流动对电、气子系统能流方程进行重构,构建全纯嵌入的电-气仿射多能流模型。为降低多能流计算的初值依赖性、提升多能流计算效率,提出一种仿射能流交替递归计算方法,将电网空载状态的状态量初值作为多能流计算起始点,基于各仿射型状态量的幂级数系数递推关系,以交替进行的方式逐阶递归计算电网、气网和耦合设备的仿射型状态量幂级数系数,求解电-气互联系统的能流分布区间。仿真结果验证了所提方法在算法保守性、收敛性和计算效率等方面的优势。

基于供冷/热系统质-量调节的区域综合能源系统动态最优能流计算

区域综合能源系统(regional integrated energy system,RIES)的最优能流计算是求解RIES的设备配置、优化调度、故障分析等问题的基础。考虑供冷/热和供气管道传输能量的动态特性,建立RIES动态最优能流计算模型,其中基于特征线法获得了供冷/热管道和供气管道动态偏微分方程的代数解析解。针对基于供冷/热系统质–量调节模式下管道能量传输时滞变量造成RIES的动态能流计算模型难以求解的问题,提出采用分段插值法获得供冷/热管道两端节点温度之间关系的近似表达式并加入动态最优能流计算模型中。此外,针对优化模型中供冷/热系统的流量与温度相乘的双线性项,提出一种能够缩紧松弛间隙的分段凸包络松弛方法将原混合整数非线性优化模型转化为混合整数二次约束规划模型,能够在保证计算精度的同时实现高效求解。最后以某个RIES算例进行分析,验证了所提方法的计算准确性和高效性,并与常用的质调节模式相比,表明在供冷/热系统质–量调节模式下能找到经济性更优的RIES运行点。

基于FLOW-3D软件的旋流起旋室水力特性数值模拟

文章采用FLOW-3D软件,通过RNGk-ε模型和volume of fluid(VOF)方法相结合,实现了竖井水平旋流泄洪洞水力特性的三维水流流场数值模拟;对开敞式进水口轴线与旋流洞轴线交角不同时起旋室的压强分布、旋流角和紊动能等水力特性进行了对比分析研究,数值模拟能够客观地反映起旋室旋流的流场特性,成果可为旋流溢洪道的研究应用提供参考.

综合能源系统建模与能流计算方法研究综述

围绕综合能源系统的能流计算问题,从网络模型及求解、不确定性能流分析方法2个层面综述了各类能流计算方法。首先,在综合能源系统网络特性建模方面,讨论了偏微分方程模型、动态特性模型和稳态特性模型及其求解方法。其次,归纳了应对系统外部输入不确定性的概率和区间2类传统能流分析方法,以及概率-区间混合不确定性能流分析方法。最后,从工程应用角度分析当前综合能源系统能流计算的难点与热点,进而对其发展方向进行展望。

基于格子Boltzmann方法的自由能密度模型

基于格子Boltzmann方法的多相流模型具有相界面自动演化、无需边界积分等优势,在模拟复杂多相流系统中获得广泛的研究和应用。本文引入自由能密度计算分子间的相互作用力,提出一种满足热力学一致性和伽利略不变性的多相流模型。使用该模型预测气液两相共存密度的结果与理论值吻合得很好,误差值为-0.01~0.01,并且在低温度下优于改进的伪势模型。同时该模型也可以模拟较大密度比的气液系统,液相与气相的密度比可达10^(7)以上。通过两相分离和液滴撞击液膜等一系列数值模拟,验证了该模型符合伽利略不变性。该模型物理清晰、易于实施,能够结合不同状态方程模拟多相流系统,具有较好的实用性和应用前景。

基于镜像原理的田间暗管排水流量计算方法

针对目前尚无适宜的计入复合型外包滤料影响的暗管排水流量计算方法,结合渗流力学中的镜像法和势流叠加原理,以宁夏银北灌区冬灌洗盐为背景,提出一种田面积水土壤饱和条件下考虑外包滤料影响的暗管流量公式.通过室内渗流槽试验和HYDRUS-2D软件模拟确定相关水力特征参数,将试验数据、数值模拟和努美罗夫解与文中计算公式进行了对比分析,结果表明:公式计算值与渗流槽试验数据、数值模拟值的相对误差分别在7.00%及2.05%以内;当外包滤料厚度小于15 cm时,计算值及引入有效半径概念的努美罗夫解与模拟值有较高吻合度;当外包滤料厚度大于15 cm时,计算值与数值模拟值更接近,并且优于努美罗夫解;暗管的排水流量随外包滤料渗透系数或厚度的增加而逐渐增大,但增长率逐渐变缓.基于镜像法提出的考虑复合外包滤料影响的田间暗管排水流量计算公式合理可行,拓展了暗管排水计算思路.

水合物相变的内输多相流流动特性研究

天然水合物在柔性立管的举升过程中会由于压力的变化发生分解,相变过程由立管底部的固液两相流到立管顶部的气液固三相流。基于计算流体力学(CFD)方法,利用FLUENT软件建立悬链线型柔性立管模型,采用Euler多相流模型,结合UDF添加源项来模拟水合物分解过程,得到了不同影响参数下立管内水合物的流动特性。结果表明:颗粒体积分数和悬挂角的增加会使立管内持气率增加,从而减小水合物运输能耗;入口速度的增大会增加立管出口处的颗粒速度,使管道中的持气率减少,速度的增大使所需泵的能量消耗增加;颗粒体积分数的增加,使立管中持气率增加,所需泵的能耗先减小后增大,即颗粒体积分数存在最优值。在实际工程中可根据需要,通过调整相关参数达到减小能耗的目的。

基于能流耦合机理的热电耦合综合能源系统潮流分析及对比

热电耦合综合能源系统对提高能源利用率、实现可持续发展具有重要意义,潮流计算作为研究稳态热电耦合综合能源系统的常用方法,能够计算出系统网络的能流分布,为后续的规划、运行、调度提供数据基础。该文基于热电耦合规律,考虑热力系统中回水热损失改进了传统热力系统模型,并结合电力系统模型组成了热电耦合综合能源系统潮流计算模型。在此基础上研究了统一求解法与分立求解法两种潮流计算方法。建立算例系统,分别采用分立求解法与统一求解法进行潮流计算,并对比分析二者的计算性能及结果。结果表明:在设定算例系统计算精度为10-2时,统一求解法与分立求解法均可满足热电耦合系统潮流计算要求。系统中电网节点功率满足基尔霍夫定律,热网由于需要工质来承载能量,在流动时产生损失时除单纯的能量损耗外还需考虑工质损失,因此回水总量少于供水总量。系统采用以热定电时,分立求解法总迭代次数为10次,耗时8.48s,统一求解法迭代次数为8次,耗时10.56 s,考虑热网和电网的相互影响时,分立求解法迭代次数和耗时大幅增加,统一求解法基本不变,因此采用以热定电时分立求解法更加简便,在考虑热网和电网的相互影响时,适合使用统一求解法。

复合夹芯导流罩流激噪声数值模拟与控制研究

航行过程中,潜艇壁面与周围流场相互作用而产生的流激噪声会对透声窗结构产生严重危害,因此,有效控制流激噪声具有非常重要的意义。首先采用统计能量法对潜艇首部模型进行流激噪声预报,根据不同航速以及距湍流层前端距离进行分析,得出不同材料对流激噪声的影响规律;其次,针对导流罩低噪声和高透声的要求提出一种3层复合夹芯结构设计,通过选用阻尼材料和设计4种铺层方案对比分析。结果表明,铺层方案为碳纤维/阻尼材料2/钛合金,铺层厚度为10 mm/10 mm/3.55 mm是降噪性能好、透声性强的最优方案,研究成果可为实际应用提供参考。

船模水动力噪声及孔腔激励载荷试验与计算对比分析

开展某远洋客船光体船模水下噪声测试及带孔腔船模的水动力激励载荷测试,并进行孔腔处稳态和瞬态流场计算,孔腔处脉动压力频谱计算曲线与试验曲线吻合较好。孔腔脉动压力线谱频率测试值与经验公式频率计算值对比良好,说明该公式在一定情况下适用于船体条形格栅孔腔线谱频率的预估。采用统计能量法分析法计算光体船模中高频流激噪声,将流体激励以频率-波数功率谱的形式施加,可大大减少流场计算工作量,适合于工程快速预估。在工程一般范围内,阻尼损耗因子取值可导致噪声结果相差5.5 dB,说明阻尼损耗因子的取值会较大影响计算结果,有必要形成材料损耗因子随频率变化的数据库,为船舶噪声快速计算提供支撑。