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。     

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。     

高压充油电缆运行中的问题和处理方法

1966年以来,我国采用高压充油电缆引出的水电站已有13座,拥有高压充油电缆49回,总长26355m。按电缆的电压等级区分:110kV的有10回,总长5052m;220kV的有34回,总长17703m;330kV的有5回,总长3600m。从20多年的运行情况看,电缆及其终端头的性能基本上是良好的;但由于制造、施工和运行经验不足,以及管理等原因,电缆在运行中出现过铅包漏油、护层绝缘降低、电缆油介质损失角正切(tgδ)值增大和失压进气等问题。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明:库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

Surveying for Water Resources

Abstract

A professional Land Surveyor (Geomatician) describes the Hydrogeologists' survey requirements of a major water resources assessment for the government of The Sultanate of Oman (1992 to 1996). The need for objective specifications is stated. Specialist terms like geoid, spheroid, Mean Sea Level are explained and how to relate spheroidal levels to the geoid. Methods like traditional survey, satellite survey, and photogrammetry are introduced. The paper encourages coordinated working for the benefit of water resource assessment and recommends employment of the professional land surveyor for major studies.     

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam,lower Kaskaskia River,Illinois, USA

Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。