一种小电流接地系统单相接地故障测距新方法

提出了一种基于广域同步信息的故障测距新方法,该方法基于线路的分布参数模型,利用横向故障电流与故障距离的关系构造了一个测距函数,利用线路两端的电压、电流同步信息,同时每假设一个故障点距离就可求出与之对应的横向故障电流值,在整条线路上利用迭代搜索的方法可求出唯一的一个最大横向故障电流,该电流的对应距离即为实际故障距离。大量仿真结果和现场试验均表明此方法具有较高的可靠性和测距精度,并且可以推广到其他类型的故障测距计算。     

基于同步相量测量的电压稳定评估算法

提出一种基于同步相量测量的电压稳定评估算法。算法中只需要利用局部同步相量测量，即被监测负荷节点的同步电压相量，及由与其相连接的同步电压相量所得到的等价电压相量，建立一等价两节点系统。最后，以被监测负荷节点的同步电压相量在等价电压相量的投影与等价电压相量幅值的一半之差，作为计算电压稳定与否的指标。将这个算法应用于一个5节点系统中，仿真结果验证了算法的正确性及合理性。     

精确双端故障测距新算法

提出一种利用线路双端故障数据进行精确故障定位的新算法。新算法利用了故障后线路两端 的电压电流相量，考虑了双端采样数据的非同步问题，通过采用分布参数模型，精确考虑了 分布电容对测距算法的影响，从而大大提高了测距算法的精确度。该算法通过EMTP仿真和实 际故障数据的验证，证明有很高的精确度。     

不受TA饱和影响的高压输电线路故障测距算法

基于线路分布参数模型，考虑电流互感器（TA）饱和或断线导致某一侧电流畸变或不可用的情况，提出了一种输电线路故障测距新算法。该方法通过分析短路序网关系，利用两侧电压和未饱和侧电流，求出不同短路类型下沿线电压和电流的分布，根据过渡阻抗的纯电阻性质，得出当且仅当在故障点处电压和流经过渡电阻的电流的相位相同，由此定位故障点。因此，该测距方法可以不受一侧TA饱和或断线的影响。ATP-EMTP仿真结果也证明了该方法正确、有效。     

故障点故障分量电流电压相量分析

故障分量原理在微机保护中大量应用,而故障分量存在于故障分量网络中,因此,有必要建立短路故障时的故障分量网络,画出故障点电流、电压故障分量相量图。按对称分量概念,求其故障点各序电流、电压,以便理解故障分量原理的微机保护。     

同杆双回线反序电流特点及其在T形线路测距中的应用

对同杆双回线的反序电流特性进行了研究，推导出双回线中存在其他支路时反序电流的计算公式及特点。该计算公式可以应用到带有同杆双回线的T形线路的故障支路判断和故障测距，利用反序正序电流计算反序正序电压，并且利用反序正序电压在故障点相等的等量关系进行故障测距。大量的EMTP仿真结果表明，所给出的支路电流与同杆双回线反序正序电流之间的关系是正确的，并且在带有同杆双回线的T形线路故障测距中显示出较大的优势。该测距方法的精度不受故障支路、故障类型、系统运行方式、故障点过渡电阻等因素的影响。     

自适应网络结构的故障行波定位方法

输电网中环路的存在会影响故障初始行波到达时间与行波传输路径的匹配,影响故障点位置的计算。为此,提出了一种自适应网络结构的故障行波定位方法。对于故障线路不包含于环路的情况,利用Floyd算法搜索故障点到网络中各节点的最短路径;对于故障线路包含于环路的情况,确定环路中初始行波到达时间最大的节点为解环点,并提出了剔除无效路径的时间判据,将复杂故障网络简化为辐射形网络。在辐射形网络中,运用基于整个电网的故障行波定位算法,实现全网综合定位。仿真结果表明,该方法实现简单,适用于任何结构的电网,能够有效弥补现有行波网络定位算法的缺陷和不足。     

基于暂态信息的小电流接地故障区段定位

提出一种适用于配电系统架空线路的小电流接地故障区段定位新方法。该方法利用故障暂态电压、电流特征频段内分量计算无功功率，根据故障点前后暂态无功功率方向的不同确定故障区段。在故障信息不易获取的检测节点处，提出利用电磁场感应获取故障暂态信息的方法，通过测量架空线路下方垂直地面方向电场获取小电流接地故障暂态电压信息，测量水平方向磁场获取故障暂态电流信息，详细阐述了最佳检测点的计算思路，并以一典型10 kV架空线路为例验证了该方法的可行性。最后阐述了利用该方法实现故障区段定位需要解决的若干关键问题。     

特高压长线路单端阻抗法单相接地故障测距

特高压长线路分布电容大，故障后波过程明显，基于集中参数模型的单端阻抗法故障测距无法适用。针对该问题，采用分布参数建模，经分析证明观测点处的负序电流可以很好地模拟故障支路负序电流（故障点电压）的相位信息。基于此，提出了一种新的阻抗法故障测距方法。该方法在故障点电压瞬时值过零点时刻计算测量阻抗，理论上不受过渡电阻的影响;基于分布参数模型，不受分布电容电流的影响。理论分析和仿真结果表明:所提出的算法具有较高的测距精度，能够满足现场应用的要求。     

一种实用的新型高压输电线路故障双端测距精确算法

提出一种新型的高压输电线路故障测距的精确算法。该算法基于线路的分布参数模型，根据故障时沿线电压的分布规律，使用搜索迭代的方法计算出故障点的位置，不要求双端的数据同步，能消除过渡电阻的影响，且无需解长线方程，也不存在伪根的判别问题，具有较高的实用价值。EMTP仿真结果显示即使在较低的采样频率下该算法仍具有较高的精度。     

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。     

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.     

Impacts of Microcystis on algal biodiversity and use of new technology to remove Microcystis and dissolved nutrients

Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%, genera richness by 66% and genera evenness by 51%. Analysis by mixed anova s demonstrated a significant interaction between treatment and time and confirmed a significant reduction in richness and evenness of phyla and genera. We also conducted a phosphate restriction assay on the algae in Mason Lake (Irvine, CA, USA) and found that the threshold needed for algal growth there was 0.02 mg L^?1 PO₄. A pilot study was then conducted to test the effectiveness of the Blue Pro? water treatment facility in removal of this colonial organism from Mason Lake, in addition to removal of dissolved nutrients required for its growth. We measured a 97% reduction in Microcystis cells, a 72% reduction in chlorophyll‐a, and a 96% reduction in phosphate after just one 10 min cycle through the unit. Our study demonstrated that removal of Microcystis colonies may allow green algae to increase in numbers. This may improve algal biodiversity, which will benefit zooplankton and fishes.     

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。     

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.     

簸箕李引黄灌区水沙分布及优化调度的经验

灌区利用水沙观测所取得的资料和试验数据，运用水沙运动力学理论，总结分析和揭示了灌区水沙分布的规律和特点。在此基础上，结合灌区的实际运行情况，围绕减少骨干渠道的淤积进行探讨、研究，进而，优化水沙调度方案。该方案实施后，骨干渠道减旅伴效果明显，取得了成功的经验。     

小湾水库大坝防渗面板及其裂缝的加固处理

小湾水库大坝防渗面板整体抗渗性能差,且存在多条裂缝,通过对面板钢丝网喷涂丙乳砂浆加固处理及其裂缝修补,大坝渗漏量明显减少,且左岸上灌浆廊道内及大坝下游坝面92～93 m高程下廊道入口处原有小股射流全部消失.     

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.