一种智能变电站电子式互感器改造的方案

笔者通过对某220 kV变电站电子式互感器缺陷进行分析,提出了电子式互感器故障处理及改造的方案。根据该变电站的实际情况,采用常规互感器加合并单元的方案取得了良好的改造效果,保证了变电站的安全稳定运行。     

数字化变电站中保护装置与电子式互感器的接口方式

简要介绍了常规变电站中电磁式互感器绕组排列、常规微机保护的可靠性设计等。提出了在数字化变电站保护装置中的独立启动元件如何考虑电子式互感器内部故障、保护装置与电子式互感器的接口等问题，以及几种保护装置与电子式互感器之间的接口方案，并对方案进行了比较。     

数字化变电站的电压互感器配置和电压切换

简要介绍了常规变电站中电压互感器的配置及电压切换。提出了在开发电子式电压电流互感器后，在数字化变电站中如何配置电子式电压互感器，以及如何进行电压切换等问题。还提出了几种电压互感器的配置方案，并对方案进行了比较，提出了数字化变电站中电压切换的方案。     

电子式光电组合电流/电压互感器中的相位补偿技术

为了解决传统电磁式互感器所面临的问题，基于光学和电子学原理的新型电子式互感器得到了广泛的重视。文中介绍了电子式光电组合电流/电压互感器中传感头部分的设计原理及其相应的信号处理过程，主要内容是如何针对传感头输出信号的特点进行适当的相位补偿，通过对多种相位补偿方法性能的分析比较，提出了新的相位补偿方法，并进一步分析了各种误差因素对新的相位补偿方法的影响，实验结果验证了新的相位补偿方法的有效性与实用性。     

电子式与电磁式互感器的比较及在智能电网中的应用

介绍了传统电磁式互感器和电子式互感器的构成及工作原理,对其优、缺点进行了比较并用具体实例进行了说明。对智能化变电站与传统变电站中的采样量进行了比较,对互感器的发展方向进行了展望。     

数字化变电站自动化系统开发建议

随着电子式互感器或合并单元的使用,数字化变电站自动化系统的设计和应用将会产生许多新问题。通过讨论罗列了一些此类问题,有些是厂商单独可以解决的,有些则需要在厂商之间协调一致才能解决。IEC 61850标准并不仅仅意味着采用统一的协议、模型,还意味着开发者在对采用IEC 61850标准的系统进行开发时,要转变思维方式,采用新的功能实现方式,才能达到IEC 61850标准所希望的目标。对采用IEC 61850标准的系统在开发过程中出现的新特点和需要解决的新问题进行了探讨,并提出了解决思路。     

数字化水电站互感器解决方案研究

阐述了电子式互感器的原理特点、优势及行业应用现状,结合水电站的实际情况,论述了电子式互感器在水电站中的应用解决方案,同时兼顾了采用常规电磁式互感器时的数字化方案,为实现水电站采样数字化、信息共享网络化提供了一种思路,为数字化水电站自动化系统的设计与建设提供了参考。     

电子式互感器数据分析系统的设计与应用

在分析电子式互感器的工作原理及其数字信号输出格式的基础上,详细设计并实现了基于WinPCap网络工具包的新型电子式互感器数据分析系统。该系统可对采样报文进行精确的实时捕获分析,并以动态波形图的方式显示瞬时的采样波形,为电子式互感器性能测试、极性校验等系列试验提供了有效的辅助分析工具。     

电子式互感器接入的光纤差动保护数据同步方法

指出了电子式互感器（ET）接入的线路光纤差动保护在数据同步方面遇到的主要困难,分析了全球定位系统（GPS）同步方法与传统数据同步方法的局限,提出了利用改进插值法进行数据同步的新方法。该方法不依赖于任何外部设备,可靠性高;不调整采样时刻,适应于IEC 60044-8标准规定的合并单元功能结构条件,并能灵活适用于线路一侧为ET一侧为传统互感器的情况。数据同步的目标始终是要保证参加差动运算的电压电流量追溯到一次侧是同一时刻的,为此,各侧ET二次变送延时的影响必须被计及到保护装置的数据同步过程之中。对保护装置而言,补偿两侧ET二次变送延时的时间差是数据同步的核心内容。对需要配置光纤差动保护的线路,ET的合并单元最好能够提供符合IEC 60044-8标准的数据输出接口。     

数字化变电站同期功能的实现

同期合闸功能是变电站自动化系统的重要功能。随着电子式互感器的应用和IEC 61850标准的推广,在数字化变电站自动化系统中,同期功能的实现方法有较大变化。文中介绍了数字化变电站自动化系统中同期功能实现方案,包括采样值接收、采样值异常处理、重采样、同期点预报等模块,该方案充分考虑了采样值的传输延时,并对传统的同期点预报算法进行了改进,使之更适应数字化变电站的应用需求。经实验室验证和现场运行证明,该方案能够安全正确地实现数字化变电站的同期功能。     

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.     

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.     

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.     

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。     

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.     

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.