SF6断路器储能电机烧损原因分析及处理

本文对江苏宜兴抽水蓄能电站机组出口断路器操作机构储能电机烧损原因进行了细致地分析,特别是对储能电机电枢回路、机械回路、并励回路以及运行温度进行了详细计算和细致分析,对断路器操作方法和储能电机控制回路提出了改进措施,并对储能电机运行维护提出了建议。     

一起LW10B-252型断路器液压机构频繁打压原因分析

为了解决一起液压机构频繁打压问题,笔者通过对该液压机构和储能控制回路进行检查分析,发现液压机构存在渗漏,且由于受到环境温度变化的影响而导致液压机构夜间频繁打压。通过更换渗漏部件和优化储能控制回路等方法解决了该断路器的频繁打压问题,并对该类型断路器的液压机构检修维护提出了针对性的建议,为今后解决类似的问题起到一定的借鉴作用。     

一起220 kV断路器跳跃现象原因分析

针对某电站220 kV线路保护改造调试过程中出现三相开关跳跃、操作箱合位灯出现“跑马灯”现象，笔者结合保护装置、操作箱、控制回路的排查情况，分析断路器发生跳跃的原因，并提出防跳回路的改进建议。结果表明：误接线导致合闸回路异常带正电、防跳回路设计缺陷导致开关反复跳跃、储能回路异常导致三相不一致保护频繁动作是断路器跳跃的原因。该研究结果可为同类断路器控制回路故障分析提供参考和借鉴。     

500 kV断路器操作回路兼容问题的实际解决

云南大朝山水电厂在500 kV断路器保护改造工程中,遇到操作箱与现地控制柜内控制回路不匹配的实际应用问题。主要涉及到断路器跳闸回路和合闸回路的监视回路、位置指示、防跳回路,在设备初次上电后出现了指示灯异常点亮、TWJ、HWJ不正确励磁的现象。本文描述了实际分析过程,提出了解决方案,并对运行情况进行介绍。     

高压断路器动作特性监测及特征曲线分析

高压断路器是电力系统最关键的开断元件之一,其运行状态直接影响到整个电力系统的稳定性和可靠性,因此,及时监测断路器开断时间和准确评估断路器的开断能力是电力系统正常运作的保障。由于大多数电站目前对断路器操动过程检测均是采用定期试验的方式,考虑到500 kV及以上线路的重要性及停机时间有限等问题,本文在对某水电站断路器实际运行参数及结构评估后,提出现场定制化的非接触式监测方法,实现了位移行程信号、线圈电流信号、储能电机电流信号等关键参量的实时监测,通过对时序信号曲线进行分析,提取了与断路器动作特性相关的多种特征参量,为进一步的性能评估、设计优化和故障诊断提供参考。     

一种高压断路器SF6压力低闭锁回路的优化方案

当500 kV气体绝缘金属封闭组合电器(GIS)断路器中SF6气体压力过低时,通过SF6密度继电器和重动继电器来闭锁断路器分合闸回路。本文针对目前某开关厂生产的500 kV高压断路器中SF6压力低闭锁回路中存在的设计缺陷,经对比分析、并结合发电厂实际运行条件,提出了相应的优化改进方案,既精简了控制回路,又符合南网相关技术标准和精益化检查标准,满足功能要求,并进一步提高了SF6压力低闭锁回路的可靠性,确保了断路器的安全稳定运行。     

断路器操作回路设计配合中的若干问题

阐述了断路器操作回路中防跳回路和跳合闸位置继电器的重要性,通过对一例断路器操作回路故障的分析,介绍了断路器防跳回路设计的现状及各省网对此的规定,对防跳回路的设置提出了自己的见解,并详细叙述了跳位继电器和合位继电器的选型要点。     

黎平变电站LW24-72.5型断路器主回路电阻超标的分析研究

鉴于500 kV黎平变电站中35 kV低压电抗器在实际运行过程中,断路器动作次数频繁,运行工作环境差,存在着较大的安全隐患,据实例对LW24-72.5型断路器主回路电阻值超标的主要相关因素进行了分析研究,提出了相应解决方案.     

断路器弹簧储能异常信号情况分析及处理方案

紧水滩水力发电厂机组断路器弹簧储能操作机构常发“弹簧储能异常”信号,通过可编程控制器对信号处理的工作流程进行优化,分析了频发断路器弹簧储能异常信号的3种情况,提出了改善弹簧储能异常信号的处理方案。     

乐滩水电厂4号机组发电机出口断路器合闸异常分析与处理

针对乐滩水电厂4号机组发电机出口断路器无法合闸并网的情况,基于断路器动作及控制原理,分析了异常现象并对同期装置及其外部回路、断路器控制回路进行排查,发现断路器分闸监视回路中存在寄生回路的情况,经处理解决了断路器合闸异常故障,为类似事件的处理提供借鉴和参考.     

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…