消弧线圈信息远传及数据管理系统的设计与实现

设计实现了消弧线圈信息远传及数据管理系统，详细阐述了该系统各个模块的功能，实现了消弧线圈运行数据、接地数据的远传和管理，为运行、管理人员掌握消弧线圈系统的运行情况、及时发现和处理接地故障提供了重要手段。     

利用SABER软件包辅助设计一种可连续调节消弧线圈

闸流式消弧线圈是一种快速、可连续调节的消弧线圈，由于这种消弧线圈结构特殊，同时又必须满足系统较高的要求，因此设计出能满足要求的闸流式消弧线圈比较困难。为此，采用了一种新型的仿真设计方法。首先，建立消弧线圈的铁心模型、线圈模型；然后，根据消弧线圈的实际结构将建立的铁心和线圈模型组合构成消弧线圈的模型，这种模型不仅反映了消弧线圈的基本电磁特性，还反映了消弧线圈的空间结构，其模型的电磁参数根据其空间结构参数计算；最后，建立消弧线圈系统的测试模型。利用SABER仿真软件对设计消弧线圈的特性进行了较全面的估算，通过实验和仿真结果的比较可以看出，文中提出的仿真模型具有较高的精度，其仿真结果比较准确地反映了消弧线圈的特性；利用该设计方法提供的参数制成的消弧线圈产品达到了设计要求。     

水轮发电机中性点消弧线圈运行档位优化选择与试验分析

以天生桥一级水电发电厂#4发电机试验为实例,分析发电机中性点消弧线圈运行档位的选择和优化。首先给出了发电机与消弧线圈的技术参数,然后根据标准要求说明了消弧线圈运行档位的选取原则,最后阐述现场试验内容与方法,并通过分析现场试验数据建议在保持电厂原有一次设备不改变的情况下,#4发电机组消弧线圈最优运行档位为2-3档。     

配电网电容电流实时测量技术

针对不对称度大的配电网，实现了自动投切可调消弧线圈并联固定电抗器的预随调接地方式，研究了配电网电容电流实时谐振测量技术。为提高电容电流测量精度，采用现场可编程门阵列（FPGA）芯片和高精度晶振精确测量注入信号的电压电流相位差，利用线性插值算法精确计算配电网谐振频率。开发了消弧线圈自动调谐测控装置，实现电容电流的精确测量。模拟实验和现场运行结果表明，该电容电流测量技术具有测量精度高、测量范围广和测量简单等特点，可适用于经消弧线圈预调式和预随调式接地电网。     

消弧线圈接地方式下外加20 Hz电源定子接地保护的应用

外加20 Hz电源定子接地保护在发电机中性点经配电变压器高阻接地方式下已有很多工程应用，但其在中性点经消弧线圈接地的发电机上还没有成功的应用经验。文中分析了外加20 Hz电源定子接地保护应用在发电机中性点经消弧线圈接地与中性点经配电变压器高阻接地存在的差别，包括计算故障过渡电阻的等值电路、消弧线圈工作参数选择与计算等，为外加20 Hz电源定子接地保护在中性点经消弧线圈接地的发电机上成功应用提供了依据,其结果已被现场试验验证。     

偏磁式消弧线圈在小容量发电机中性点的应用

目前国内单机容量10~100 MW,机端出口电压10.5 kV,定子基波接地保护投告警,中性点普遍采用常规消弧线圈补偿。本文针对上述机组没有甩负荷、机组频率在额定50Hz、机组暂态或者动态过电压不会超过2.6倍相电压这一点至关重要的试验结论,阐述常规消弧线圈对比偏磁式消弧线圈的优缺点,展望偏磁式消弧线圈应用于小容量机组中性点的前景。     

消弧线圈在中压电网中的应用分析

随着电网的发展，大量电缆应用到配电网中，当系统发生单相接地故障时，电容电流变大，威胁到电网的安全、稳定运行。文章分析了电容电流的产生和危害及消弧线圈在非有效接地系统中应用的必要性；阐述了消弧线圈的工作原理、容量选择等相关问题；对各类型消弧线圈的优缺点进行了分析。     

基于对称法与相位法的新型消弧线圈

分析了当前自动跟踪补偿消弧线圈技术的发展以及存在的问题，提出了基于对称法与相位法相结合的新型消弧线圈设计方案，介绍了电容电流检测方法和装置结构。该方法利用了零序电压U₀与脱谐度υ关系曲线的对称性以及零序电压与线电压的相位关系，无需反复调节消弧线圈电感值就可快速、精确地跟踪测量电网电容电流。根据该方法研制出的新型消弧线圈试验和现场运行均表明，该型消弧线圈具有响应速度快、补偿精度高、无机械动作可靠性高等特点。     

调匝式消弧线圈自动调谐新方法

对调匝式消弧线圈的自动调谐，提出了利用谐振法结合曲线拟合法测量电容电流的新方法：找出谐振点左右的3点，代入拟合曲线方程，求出谐振点的感抗值（等于系统容抗），由此求出电容电流。该方法具有状态识别功能，能区分线路投切状态和调谐状态，无需相互通信便可实现变电站内部和变电站之间的多台消弧线圈的自动并联。模拟电网试验和现场运行试验结果令人满意。     

电气一次设备知识问答(二)

——消弧线圈常见故障及处理;带消弧线圈的非直接接地系统接地故障点如何寻找;输电线路并联电抗器的作用。1消弧线圈通常有哪些故障?应如何处理?消弧线圈常见的故障有:(1)消弧线圈单相接地。     

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.     

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.     

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.     

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。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．     

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.     

掺MgO混凝土的宏细观试验研究

利用MgO膨胀剂的延迟微膨胀效应能显著提高大体积混凝土的力学性能,产生的预压应力还能有效提高大体积混凝土抵抗温度开裂的能力,但目前对其微观机理研究不多。采用宏观与微观相结合的方式,研究了不同活性指数、不同掺量的MgO混凝土的力学性能,利用SEM/EDS微观分析手段揭示了MgO对混凝土性能影响的作用机理。试验结果表明：MgO取代部分水泥掺入混凝土中,混凝土的力学性能降低;掺量为4%~5%时,活性指数为100s的MgO混凝土的膨胀率大于活性指数为50 s的MgO混凝土;MgO混凝土的膨胀特性与Ca,Si,Mg,Al等元素的分布情况有关,掺入的MgO将改变界面区Ca,Si,Mg元素的富集特性,Ca元素和Mg元素更易于在界面区富集,导致混凝土宏观力学性能的降低。