Energy transmission modes based on Tabu search and particle swarm hybrid optimization algorithm

In China, economic centers are far from energy storage bases, so it is significant to select a proper energy transferring mode to improve the efficiency of energy usage. To solve this problem, an optimal allocation model based on energy transfer mode was proposed after objective function for optimizing energy using efficiency was established, and then, a new Tabu search and particle swarm hybrid optimizing algorithm was proposed to find solutions. While actual data of energy demand and distribution in China were selected for analysis, the economic critical value in comparison between the long-distance coal transfer and electric power transmission was gained. Based on the above discussion, some proposals were put forward for optimal allocation of energy transfer modes in China. By comparing other three traditional methods that are based on regional price differences, freight rates and annual cost with the proposed method, the result indicates that the economic efficiency of the energy transfer can be enhanced by 3.14%, 5.78% and 6.01%, respectively.     

特高压OPGW结构的研究

OPGW的性能主要由其结构确定,在无从全面考察特高压OPGW设计、制造、试验、施工及运行经验的前提下,有必要对用于高电压、远距离、大容量输电及大区域负荷联网的特高压线路OPGW结构进行研究。文章在论述了特高压OPGW七个方面的特征后,推荐层绞光纤松套管与中心热挤压厚壁铝管组合的光单元 铝包钢内层圆绞线 铝包钢外层扇形绞线的OPGW结构,重点分析了故障电流及故障电流切除时间、故障电流导致各元件的温升与限制、OPGW的伸长、对光纤的保护、光纤的余长与控制、光纤的选择、雷击的影响、特性参数、绞合线与综合性能、工程配置原则,此外,还提出了选用楔型耐张线夹等方面的建议。     

Digital simulation studies on long transmission line protection based on balance of energy

0　ＩＮＴＲＯＤＵＣＴＩＯＮＡｐｐｌｉｃａｔｉｏｎｏｆｎｏｒｍａｌｃｕｒｒｅｎｔｄｉｆｆｅｒｅｎｔｉａｌｒｅｌａｙｏｎｌｏｎｇＵＨＶｔｒａｎｓｍｉｓｓｉｏｎｌｉｎｅｓａｒｅｌｉｍｉｔｅｄｂｅｃａｕｓｅｏｆｄｉｓｔｒｉｂｕｔｅｄｃａｐａｃｉｔａｎｃｅｃｕｒｒｅｎｔ[1,2 ] .Ｔｏｐｒｅｖｅｎｔｔｈｅｓｙｍｐａｔｈｙｔｒｉｐｃａｕｓｅｄｂｙｄｉｓｔｒｉｂｕｔｅｄｃａｐａｃｉｔａｎｃｅｃｕｒ ｒｅｎｔ,ｔｈｅｔｒｉｐｐｉｎｇｃｕｒｒｅｎｔｔｈｒｅｓｈｏｌｄｉｓｕｓｕａｌｌｙｅｌｅｖａｔ ｅｄ .Ｔｈｉｓａｆｆｅ…     

UHV/CVD自对准生长Ge量子点(英文)

在超高真空化学汽相淀积设备(UHV/CVD)上生长了小尺寸、大密度、垂直自对准的Ge量子点。采用原子力显微镜分析量子点的尺寸,可优化其生长温度和时间,在550℃,15s的条件下生长出尺寸最小的量子点,直径30nm,高约2nm。最上层多层结构Ge量子点中岛状量子点的比例为75%,其直径66nm,高11nm,密度4.5×109cm-2。利用透射电子显微镜分析了垂直自对准的Ge量子点的截面形貌,结果表明多层结构Ge量子点是垂直自对准的。Ge量子点及其浸润层的喇曼谱峰位分别为299cm-1和417cm-1,说明Ge量子点是应变的并且界面存在互混现象。采用光荧光谱分析了Ge量子点的光学特性。     

电磁和放电环境对水果采后生理影响的研究

实验研究了人工电磁场环境及由高电场而派生的放电环境对芒果，柑桔，苹果等水果采后生理的影响。结果表明，利用一定的电场和放电环境可以延缓水果在贮藏中的衰老过程，有利于保鲜。     

A GeSi-buffer structure for growth of high-quality GaAs epitaxial layers on a Si substrate

A SiGe-buffer structure for growth of high-quality GaAs layers on a Si (100) substrate is proposed. For the growth of this SiGe-buffer structure, a 0.8-μm Si_0.1 Ge_0.9 layer was first grown. Because of the large mismatch between this layer and the Si substrate, many dislocations formed near the interface and in the low part of the Si_0.1Ge_0.9 layer. A 0.8-μm Si_0.05Ge_0.95 layer and a 1-μm top Ge layer were subsequently grown. The strained Si_0.05Ge_0.95/Si_0.1Ge_0.9 and Ge/Si_0.05Ge_0.95 interfaces formed can bend and terminate the upward-propagated dislocations very effectively. An in-situ annealing process is also performed for each individual layer. Finally, a 1–3-μm GaAs film was grown by metal-organic chemical vapor deposition (MOCVD) at 600°C. The experimental results show that the dislocation density in the top Ge and GaAs layers can be greatly reduced, and the surface was kept very smooth after growth, while the total thickness of the structure was only 5.1 μm (2.6-μm SiGe-buffer structure +2.5-μm GaAs layer).     

特高压交流变电站母线短路电流的影响因素分析

从特高压交流变电站高、中压侧母线等值自阻抗的组成要素出发,分析确定了特高压变电站母线短路电流的影响因素,给定了特高压变电站1 000 kV侧交流电网结构、特高压交流变电站主变压器以及500 kV侧交流电网结构对高压侧和中压侧母线短路电流影响的比重关系。分析结果表明,特高压交流变电站高压侧母线的短路电流主要受1 000 kV侧交流电网结构的影响,而中压侧母线短路电流主要受500 kV侧电网结构和特高压站主变压器的影响。研究结论可为特高压交流站近区电网限流措施的优化提供理论支撑。     

应对特高压环网故障热稳问题的多直流紧急控制策略

首先提出一种定位特高压环网开断故障下热稳问题的精准、遍历搜寻方法;然后建立了特高压直流矫正环网热稳问题的优化模型,并提出了一种快速、实用的定步长梯度下降寻优方法。求解过程中,提出了特高压环网目标线路的等效送、受端概念;同时,多直流调制灵敏度、调制方向、调制步长以及每一迭代步调制效果等的给出增强了控制策略寻优的物理意义。最后,基于实际的特高压环网工程,采用PSD-BPA仿真软件,对所提方法和策略的有效性进行了仿真验证。     

一起1000kV变压器电压比误差偏大原因分析

分析了特高压自耦无励磁变压器的调压方式,阐述了其调压补偿变的工作原理,通过一起特高压主变整体变中压对低压电压比误差偏大现象,分析了不同挡位下的电压计算结果以及误差偏大原因。     

Low-Temperature Friction in the XPS Analytical Ultrahigh Vacuum Tribotester

In this work, we present the capability of ultrahigh vacuum analytical tribometry for studying mechanisms of friction at low temperatures. We investigated the low-temperature frictional behavior of two different materials: ice and polyethylene (PE). We successfully formed a thin layer of ice on a steel surface, at temperature as low as 123 K in an ultrahigh vacuum. The surface characterization technique used for this study was X-ray photoelectron spectroscopy (XPS). We investigated the frictional behavior of such a thin ice layer. The changing friction as a function of temperature indicates that the ice might undergo pre-melting even at temperatures below 123 K. A polyethylene (PE) film previously deposited on a metal surface also showed changing friction as a function of temperature in the range 123 to 400 K. As there is no change in the nature of the surface chemistry of the polymer, as indicated by XPS, the results are therefore interpreted in terms of change in ductile-to-brittle transition of the polymer film over the temperature range. This work enables the fundamental investigation of friction at low temperatures with the help of surface analysis.