考虑小水电启停策略的准入容量计算

随着分布式电源的大力发展，其对原有系统产生了巨大影响。文中以小水电为例，首先分析分布式电源的启停对无功电压控制的影响，然后给出考虑单个分布式电源启停的准入极限功率计算模型。接着分析了多个分布式电源接入系统后，原有的计算模型结果可能过于乐观，提出了多分布式电源接入的至少准入容量的概念，它反映了“最恶劣”机组组合情况下的准入极限功率，并给出了基于主从决策的双层优化模型和求解算法。最后用IEEE 112节点系统的仿真结果证明了模型、算法的有效性。     

考虑配电网电压调节的分布式电源准入功率极限计算

随着分布式电源的大力发展，其对原有系统产生很大影响。分析了有载调压变压器分接头发生调节振荡的条件。讨论了分散电源的接入对变压器分接头对母线电压灵敏度 aVt 这一重要参数的影响，指出了分散电源的接入有可能使变压器分接头发生调节振荡，进而得出了考虑振荡约束的准入功率极限模型。最后运用112节点系统的算例证明了模型的有效性。     

基于配电网节点边际容量成本的分布式电源规划

分布式电源（DG）接入配电网可能导致现有供电设备得不到充分利用，产生沉没成本。引入配电网节点边际容量成本（LMCC）以反映各节点容量的紧张程度，同时给出DG单位容量成本的计算方法。在此基础上，以DG单位容量成本小于接入点的边际容量成本作为DG接入的判据，提出一种规划DG位置和容量的新方法。算例结果验证了方法的可行性。     

分布式发电对配电网电压分布的影响

靠近负荷中心的分布式发电系统对配电网有着多方面影响。文中研究了分布式电源接入放射状链式配电网络前后负荷节点电压的变化。针对开式配电网，运用潮流程序进行多分布式电源接入后电压分布的计算。提出专门评价节点电压前后变化的指标。结合分布式电源出力变化、接入位置变化以及与线路电压调节配合的试验，全面总结了分布式电源在配电网中接入位置、出力限制等方面的运行规律。研究结果表明只有合理正确运用分布式电源，才能真正发挥电压支撑作用。     

含分布式电源配电网潮流问题的解决策略

研究了分布式发电系统接入电网的数学模型,对常见的几种分布式电源的节点进行了划分,归结为PQ节点,PV节点和P-Q（V）节点。在此基础上,基于MATLAB的计算功能,利用前推回代潮流算法原理,对有分布式电源接入的配电网系统进行潮流计算,计算过程采用改进的算法,最后对所提出算法的计算速度、收敛性等进行了分析。结果表明,该模型和方法能够快速、方便求解含多分布式电源的配电网潮流。     

分布式电源对配电网过电压的影响

随着分布式电源（DG）的引入，配电网从原来辐射型无源电网变成了有源环网，给系统安全运行带来了新的挑战。文中对配电网引入DG后可能出现的各种过电压问题进行了比较全面的分析与讨论;利用PSCAD软件对某变电所10 kV配电网进行了仿真验证，并对各种参数配置下的过电压水平进行比较分析。结果表明，所接入DG的类型与容量、负荷水平及配电网参数对产生配电网过电压有着重大的影响。     

配电网节点边际容量成本及应用

分析了现有配电网边际容量成本的不足。通过将支路增量成本合理地分摊到各负荷节点,提出配电网节点边际容量成本（LMCC）的概念,反映未来各节点负荷占用供电容量的成本。LMCC基于配电网供电容量的利用现状和负荷增长趋势,并不依赖于未来规划网架,因而具有较强的可操作性。最后,讨论了LMCC在配电网规划、容量定价、需求侧管理和分布式电源接入中的应用前景。     

含分布式电源的配电网供电恢复的多代理方法

针对含分布式电源的配电系统，特别在考虑了由分布式电源和负荷组成微网运行的情况下，建立了以恢复负荷最多、开关操作数最少为目标的供电恢复模型。在提出配网调度中心、微网、分布式电源三者的分层协调控制策略的基础上，应用多代理理论，建立了一个由全系统控制协调代理（CAG）、微网控制代理（MGAG）、分布式电源代理（DGAG）以及母线代理（BAG）组成的多代理系统，在保证配电网辐射状运行、满足配电网电压与电流及馈线容量等约束条件的情况下进行供电恢复。通过分析一个含2个变电站、14条母线和4个分布式电源的配电系统的单重及多重故障供电恢复问题验证了该方法的有效性。     

计及气候、含风力发电的配电系统可靠性评估研究

分布式电源（distributed generation,DG）的接入使配电系统从辐射型的网络变为遍布中小电源和用户的互联网络,将对传统配电系统产生巨大的影响。而风力发电机（wind turbine generation,WTG）凭借其无污染、建造费用低、发电灵活等优势越来越多地被作为分布式电源接入配电网。但由于其自身功率输出随机性强的特点,对传统的分布式电源接入配电网带来了一定的影响。在充分考虑了气候因素对WTG功率输出和配电网馈线故障率的影响的同时,结合WTG的多状态模型与配电网孤岛运行方式,对含有气候因素并以风力发电机作为分布式电源的配电系统的可靠性评估情况进行了阐述,希望电网规划人员在选择最优方案时能够考虑由上述因素带来的影响。     

区域电网调峰调频电源需求与容量配置研究

调峰调频电源对因日益增加的电网峰谷差和不稳定的新能源接入引起的电网不稳定问题作用巨大。考虑区域电网的运行现状,根据系统的峰谷差和备用容量确定系统总的调峰容量需求,然后再根据各种电源的调峰深度计算出系统对调峰调频电源容量的需求,最后对调峰调频电源的配置和新业务模式进行探讨。     

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.     

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.     

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。     

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.     

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.     

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.