发电机定子现场下线施工工艺

发电机定子现场下线工作量大，施工工艺复杂，对施工的环境条件要求很高。江垭水电站为地下式厂房，施工期间空气相对湿度大，施工场地小，施工相互干扰大。叙述了江垭水电站发电机定子现场下线的施工工艺，介绍了定子电气试验的结果，并对如何控制发电机电晕电压采取的施工措施提出了看法。     

皂市水电站发电机定子下线施工

皂市水电站安装两台混流式水轮发电机组,发电机定子绕组为双并联支路三相条形波绕组.由于机组技术参数安装工艺等要求高,且工期紧,发电机定子现场下线工期紧,工序多,工作量大,施工工艺组织很重要.重点介绍了皂市水电站发电机定子的下线准备与主要工艺特点,可供类似下线施工参考.     

鲁地拉电站定子下线工艺技术

云南鲁地拉水电站发电机定子下线在定子叠片及磁化试验完成后在机坑进行,整个下线工艺复杂。作为发电机的核心设备,定子绕组安装的质量控制,直接关系到发电机组运行工况的好坏以及机组的安全运行,所以发电机定子下线施工工艺是发电机组安装过程中的重中之重。本文从鲁地拉电站360 MW发电机定子下线的施工工艺角度,重点介绍了鲁地拉水电站发电机定子的下线准备与主要工艺特点,以及定子绕组电气试验的结果,同时根据现场实际情况对控制发电机电晕电压采取的施工措施提出了一些见解。     

高海拔大容量叠绕组定子下线施工工艺探究

发电机定子下线是机组安装中及其重要的一项工作,定子下线的质量直接影响着机组运行的稳定性及可靠性。定子下线过程中经常发生由于施工环境恶劣防护措施不到位或施工工艺执行不到位导致定子下线耐压试验放电,线棒击穿的事件。特别是高海拔地区,由于空气稀薄,气候干燥,高海拔低气压将导致定子绕组局部放电起始电压降低,绝缘性能降低,耐压试验过程中放电、线棒击穿的概率增大,因此解决整体耐压试验过程中放电、线棒击穿,提高耐压试验一次合格率是定子下线施工的关键技术。本文从高海拔地区水电站定子下线施工工艺的现状入手,通过对高海拔大容量叠绕组定子下线施工过程中施工准备、施工流程、施工方法、施工工艺等进行优化分析总结,使高海拔大容量叠绕组定子下线施工耐压试验一次性顺利通过,施工工艺取得了很大进步,工程施工质量也稳步提升。     

大岗山水电站发电机定子下线工艺

定子是水轮发电机组重要组成部分,定子下线工艺及质量关系到机组安全运行。大岗山水电站发电机定子下线在地下厂房进行,工艺复杂,自然环境条件差。叙述了大岗山水电站定子下线采用的施工工艺及质量控制要点,可作为同类型大型水轮发电机组参考。     

索风营水电站发电机定子下线质量控制

水轮发电机定子在现场进行整体下线时,如何更好地控制下线质量,关系到将来机组安全运行的健康水平。由于索风营水电站发电机定子下线的工期短、任务重、环境条件恶劣,施工单位在施工过程中采取了加强工序管理、提高工艺水平等措施,保证了下线质量。现将实际工作中总结的几点看法提出来,仅供参考。     

乌弄龙水电站发电机定子铁芯叠装、绕组下线工艺

乌弄龙水电站发电机为三相立轴半伞式同步发电机,采用全空气冷却方式。其定子作为发电机的核心设备,铁芯叠装、绕组下线的质量控制,将直接关系到发电机运行工况的好坏以及机组的安全稳定运行,因此,在定子铁芯叠装及绕组下线过程中,严格把控施工工艺是必要的。从发电机定子安装的施工工艺角度,概述了乌弄龙电站铁芯叠装、绕组下线过程中使用的工艺、注意事项。     

炳灵水电站发电机定子组装

炳灵水电站安装5台单机容量为48 MW的灯泡贯流式水轮发电机组.发电机定子总质量123.7 t,外形尺寸Φ7 230 mm×3 350 mm,机座为分3瓣结构.定子组装采用的是现场焊接机座现场叠片的组装方式,这样可增加定子的整体刚度减小机组运行过程中产生的振动、噪声、发热,提高了发电机运行的可靠性.但足在现场组装其施工条件要逊于工厂,所以定子叠片、下线时的现场环境因素足安装单位要重点考虑的问题.     

清远抽水蓄能电站电动发电机定子下线浅析

大型抽水蓄能电站电动发电机定子下线一般都有工作的场地相对较小、环境要求高、组装工艺精度要求高、工序多、过程极其复杂等特点。本文结合清远抽水蓄能电站1号发电机组,介绍了发电机定子现场下线施工过程和施工技术,阐述了定子电气试验的测试结果。分析了现场下线的问题以及影响试验的因素,并提出了处理方法,供同类抽水蓄能电站定子下线施工参考。     

三峡左岸电站VGS机组定子下线工艺

三峡电站为目前国内最大水电站。发电机定子分瓣运到工地现场组装、叠片后在机坑内完成定子线棒嵌装、槽楔装配、电接头焊接、线棒端部绑扎、支持环安装绑扎、汇流铜环安装与焊接、水接头配制焊接与安装、绝缘盒安装、气密水压及流量试验、定子喷漆及整体耐压等定子下线的全部工作，并已成功地完成了3台机组的定子下线工作，填补了国内该项目的空白，为特大型水电站定子下线施工积累了宝贵的经验。     

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。     

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。     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。     

Fish assemblage response to recent mitigation of a channelized warmwater stream

Various designs of low‐head dams are used to rehabilitate streams or forestall upstream channel incision after channelization. We report on the efficacy of using notched sills and grade control structures (GCS) to restore the fish assemblage in Luxapallila Creek, Mississippi. We tested the null hypotheses that habitat variables and species richness, evenness, and assemblage structure would not differ among: (1) a channelized segment with no modifications; (2) a channelized segment mitigated by the installation of sills and GCS; (3) a segment upstream of the installations and undergoing channel incision; and (4) an unaltered segment. Although habitat variables changed, neither species richness, evenness, nor fish assemblage structure differed between mitigated and channelized segments with both exhibiting less richness and different assemblage structures than the unaltered segment. Lack of differences in species richness between the incised and unaltered segments suggest that the GCS may have halted the negative effects of upstream channel incision before species were extirpated. Conspicuous habitat differences between the altered (channelized and mitigated) and unaltered segments were lack of backwaters and canopy coverage and finer substrates in the altered segments. Our results suggest a more comprehensive rehabilitation strategy is required in Luxapallila Creek. Published in 2003 by John Wiley & Sons, Ltd.     

NUMERICAL STUDY OF WAVE EFFECTS ON SURFACE WIND STRESS AND SURFACE MIXING LENGTH BY THREE-DIMENSIONAL CIRCULATION MODELING

1. INTRODUCTION Coastal and continental shelf regions are characterized by intensive interaction between wave and current. These regions are of great economic significance to mankind. Therefore, the modeling of wave and current as well as their mutual int…