水电厂厂用电备用电源自动投入方式的探讨

水电厂厂用电备用电源的可靠与否，直接关系着水电厂的安全运行；面临轩用电源的投入方式也直接影响着厂用电供电的可靠性，常规的备用电源自动投入装置，是靠继电器的逻辑控制来完成的，对复杂的接线既困难又不可靠，隔河岩水电厂通过技术改造，将厂用电６ＫＶ备用电源由常规的备自投改造成用计算机控制的软件备自投，用厂用电现地控制单元进行监控，实现对较复杂的、多个电源点的６ＫＶ厂用电系统的备用电源自动投入，这样既提高了     

柳洪水电站厂用电结构及其运行方式分析

柳洪水电站装机3台,单机容量为60 MW,厂房为地下厂房。厂用电供电区分为厂区、调压井、闸首,联合开关站和流域控制中心,供电区分散,供电距离长。厂用电供电采用10 kV变400 V分部供电。厂区内采用400 V混合供电,电源引自地方网和1、3号发电机出口,可互为备用;其他厂用电由2号发电机和地方电网供电。由于电站只有一回220 kV出线,而地方电网又为一孤立电网,因此厂用电供电可靠性差。建议增设柴油发电机作为厂用电的备用电源,以增加其可靠性。     

三河口水电站厂用电系统设计

三河口水电站既有发电又有供水要求,对厂用电系统的供电的可靠性和灵活性要求较高。通过对三河口水电站厂用电系统的电源引接、接线方式等方面的问题进行探讨,提出采用发电机10.5kV电压母线接两路厂用主工作电源,另引接两路外来10kV厂用备用电源供电,成功解决了机组直接启动时,母线电压降低对厂用系统造成的影响,为三河口电站的安全运行奠定了基础。     

380V厂用电系统优化

四川广安发电有限责任公司300 MW机组厂用电系统部分低压配电动力中心（PC）、电动机控制中心（MCC）及其电源进线开关配置不合理,在机组厂用电故障时,对机组及其辅机设备的运行构成安全隐患。分析了一期300 MW机组380 V厂用电系统存在的隐患及危害,提出了优化方案,确保了机组厂用电的安全供电。     

过军渡水电站复杂接线厂用电系统微机备自投的运用

厂用电系统是保障水电站设备正常运行的重要设施,厂用电中断,轻则引起故障停机,严重时则会导致电厂解列而引发事故.因此,厂用电系统通常采用多电源接线方式来保证供电可靠性,采用微机备自投装置实现主、备供电源间的自动投切.通过对过军渡水电站"三进二分段"复杂接线厂用电系统备自投优化应用的介绍,交流分析了基于微机备自投双机联动、...     

微机和可编程控制器在备用电源中的应用

介绍隔河岩水电厂利用微机及可编程控制器对厂用电（6kV和0．4kV）备用电源自动投入功能的改造情况,改造后实现了厂用电源多种运行方式的备投,大大提高了供电的可靠性。     

三峡电站厂用电及坝区供电系统设计特点

三峡水利枢纽厂用电及坝区用电系统具有供电范围广、用电负荷大、供电距离远、单台电机容量大、供电可靠性要求高等特点。针对上述特点，对三峡电站厂用电的电源引接、电压等级选择、接线方案等进行了详细的比较和探讨，以满足电站厂用电和坝区供电的可靠性。     

浅析三峡左岸电站厂用电的供电可靠性

对三峡左岸电站厂用电系统的供电可靠性从10kV电力供电以及机组交流控制电源的设计结构上进行了分析，首先，厂用电的供电是有保障的，但是，可能是由于设计从电站建设的经济性考虑，省去了部分设备，因而厂用电的供电方式有所改变，从分析得出：厂用电一旦遇到不可知事故时，其抵御能力将有所下降。     

提高三峡左岸电站厂用电系统可靠性的措施

研究三峡左岸电站10kV和400V厂用电系统的特点以及发电初期存在的主要问题，并通过改进辅助设备的供电方式和提高辅助设备对供电的适应性、强化厂用电系统多级保护的配合关系保证其选择性以及对重要厂用电负荷提供3路400V供电电源等措施，使得厂用电系统的可靠性大大提高，从而保证了机组的稳定运行。     

百龙滩水电站厂用电系统的布置、保护及监控

百龙滩水电站厂用电１０．５ ｋＶ 和０ ．４ ｋＶ两级电压，采用机组自用电和全厂公用电混合供电方式，形成了双层辐射式供电，母线之间设置了厂用备用电源自动投入装置，主要设备设置了多重保护，系统实现了计算机远方集中监视和控制，整个厂用电系统体现了安全可靠、方便的特点。     

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。     

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.     

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。     

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.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

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.