500 kV高压电缆外护套环流在线监测装置故障分析与处理北大核心

统计了龙滩水电厂500 kV交联聚乙烯(XLPE)绝缘电力电缆外护套环流在线监测装置出现故障的类型,并根据故障情况通过理论计算分析故障产生的原因,提出了合理的解决方案,为高压电缆接地环流在线监测的故障的分析及处理起到指导作用。     

500 kV高压电缆外护套环流在线监测装置故障分析与处理

统计了龙滩水电厂500 kV交联聚乙烯(XLPE)绝缘电力电缆外护套环流在线监测装置出现故障的类型,并根据故障情况通过理论计算分析故障产生的原因,提出了合理的解决方案,为高压电缆接地环流在线监测的故障的分析及处理起到指导作用。     

瀑布沟水电站500kV高压电缆保护国产化改造

结合瀑布沟水电站500 kV高压电缆保护国产化改造的成功案例,阐述了原高压电缆保护配置情况、存在的问题以及改造方案、关键技术点,为国内大型洞式水电站高压电缆继电保护方案的设计及改造升级提供参考.     

东风水电站高压电缆的结构及特性

东风水电站220kV开关站至出线平台的高压引线是采用瑞典ABB公司生产的220kV XLPE绝缘电力电缆。该高压电缆的结构、作用及其技术特性介绍如下: 该高压电缆是交联聚乙烯高压电缆,型号为F×(BT)K,1×630mm~2B型,220kV。电缆由铜导体、绝缘材料、护层等10层材料组成,其直径为112mm,电缆终端的外绝缘     

龙滩工程关键设备国产化的实施和体会

龙滩水电站是目前我国已投产电站中仅次于三峡的第二大水电站。在工程机电建设方面,龙滩工程本着“客观、实用、经济”的理念,在推动水电站关键设备国产化、振兴民族工业方面进行了积极的探索和尝试。首次实现了700MW级水轮发电机组、500kV三相组合式变压器、500kV交联聚乙烯绝缘电缆、巨型水电站监控系统设备等关键设备的国产化...     

220kV交联聚乙烯绝缘电力电缆工程设计

通过对220kV交联聚乙烯绝缘电力电缆在下板地电站的设计参数,敷设路径,安装方式,护层的接地方式,电缆的温度监测设备,电缆的防火设计的介绍,为220kV交联聚乙烯绝缘电力电缆在大中型水电站的设计提供参考。     

单芯高压电缆在向家坝水电站工程中的运用

详细介绍向家坝水电站骨料输送线隧洞施工中,在可能出现"瓦斯"和"硫化氢"等易燃、易爆和腐蚀性气体的隧洞中,成功应用的单芯高压绝缘电缆进行洞内10 kV供电技术.     

瀑布沟水电站500kV高压电缆敷设成功

2009年7月2日,由中国葛洲坝集团机电建设公司承担的瀑布沟水电站6号机组500kV高压电缆敷设工程圆满结束,这是该公司首次采用专业电缆输送机敷设500kV高压电缆。瀑布沟水电站共安装6台机组,采用六回500kV高压电缆分别出线。从地下厂房主变室的高压电缆层连接到地面开关站GIS开关设备上,共需敷设电缆18根,     

构皮滩水电站500 kV电缆选型设计

构皮滩水电站主变压器布置在地下洞室内,高压配电装置布置在地面,主变压器与地面500 kV开关站采用500kV XLPE电缆连接,电缆通过垂直竖井和水平廊道引至开关站,单回电缆长度约为660～770 m。简要介绍了500 kV电缆设计中重点考虑的几个技术问题,如主变压器的布置位置、高压出线方式、电缆的选型及截面的选择、电缆护套工频感应过电压计算等。     

向家坝右岸电站500kV高压电缆安装与试验

金沙江向家坝右岸电站500 kV高压电缆使用国产化电缆,是目前国内生产电压等级最高的高压电缆。高压电缆安装施工难度大、安装垂直度高、控制难度大、安全风险大。详细介绍了高压电缆敷设工艺及控制、电缆头制作及附件安装、电缆试验,并对电缆敷设中遇到的问题提出改进建议。电缆敷设工艺、质量、安全性较好,一次性通过高压试验,制造、安装质量满足设计要求。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。