水轮机导叶关闭规律对大波动过渡过程的影响分析

 在对水电站过渡过程进行调节保证计算过程中,利 用Matlab软件编制的水电机组仿真程序,探讨了导叶两段关闭过程中3个关键因素,即第一 段关闭时间、第二段关闭时间和导叶位置拐点开度对机组转速和蜗壳水压的影响。根据实 例计算结果得出的曲线图,分别确定了第一段关闭时间为6 s,第二段关闭时间为12 s,导 叶位置拐点开度为65%。所得参数优化了导叶关闭规律,有效地解决了在甩负荷过渡过程中 机组转速上升和蜗壳水压上升之间的矛盾。      

可逆式机组导叶和进水球阀协联关闭规律研究

可逆式机组水力过渡过程分析与控制是保证抽水蓄能电站安全稳定运行的主要因素。本文以清远抽水蓄能电站导叶关闭规律和进水球阀协联关闭规律的研究为例,基于数值模拟研究机组导叶和进水球阀关闭规律对抽水蓄能机组水轮机工况水力过渡过程的影响,同时结合现场试验数据进行验证分析,模拟可逆式机组及其水力机械系统的水力过渡过程。结果表明:为使抽水蓄能机组调保参数满足要求,应选择合适的导叶关闭时间和关闭规律;进水球阀折线关闭比传统直线关闭更有利于改善抽水蓄能机组水力过渡过程;机组导叶正常关闭时,调保参数比导叶拒动更能满足控制要求。     

高海拔地区大容量机组尾水管进口压力的控制研究

为了使高海拔地区大容量机组水力过渡过程中尾水管进口压力满足规范要求,选择合理的导叶关闭过程至关重要,导叶关闭过程是水力过渡过程中解决水电站运行安全问题最经济、最常用的措施之一。结合某高海拔地区大容量机组水电站工程实例,采用特征线计算方法,应用过渡过程软件进行仿真计算研究。结果表明:对于高海拔地区大容量机组水电站,选择合理的导叶折线关闭规律,能有效地改善尾水管进口压力,从而满足按海拔高程修正后的控制标准。研究成果可为规范控制高海拔地区大容量机组水电站水力过渡过程中尾水管的进口压力提供参考。     

基于C平台的水力过渡过程计算研究

为了准确预测机组过渡过程时的状况,推荐较为合理的导叶关闭时间和规律,以七里塘电站为例,应用基于C程序编制的过渡过程计算程序,结合电站引水系统和机组参数,计算不同工况下的结果,与实际运行时导叶设定的关闭规律和时间对比,结果表明,程序计算结果与实际运行规律很接近,说明该程序应用于计算电站过渡过程是可行的。     

阿尔塔什水利枢纽水电站引水系统过渡过程分析

阿尔塔什水利枢纽水电站引水系统长度较长。通过调压室过渡过程计算优化调压室的尺寸,既而通过对导叶关闭规律进行比较计算,确定机组最短关闭时间;再通过小波动过渡过程计算分析系统的小波动过程是否稳定;通过水力干扰计算判断被干扰机组的水头、流量、效率、机组轴力矩变化是否超过允许范围。研究结论为电站引水系统设计提供依据。     

浅谈延时10S装置在黑麋峰电厂的应用

针对导叶关闭规律对机组过渡过程的影响,提出导叶延时关闭的关闭规律,并详细介绍了延时关闭的实现,对比分析有延时与无延时的计算结果。现场试验表明,延时10S关闭导叶确保了机组飞选转速在允许范围内,并有效降低了榆水系统中的水击压力上升值,为电站的安全提供了依据。     

抽水蓄能电站上调最高水位控制工况

在抽水蓄能电站水力过渡过程计算中，可逆机组满功率抽水全失电导叶紧急关闭工况是一个值得重视的水力过渡过程计算工况．以浙江省溪口抽水蓄能电站为例，比较计算了可逆机组满负荷发电全弃荷导叶紧急关闭和满功率抽水全失电导叶紧急关闭两种过渡过程工况的上游调压室最高水位控制值，并分析了有关参数（如输水道水头损失系数、竖井面积、上室面积、引水隧洞长度）变化对该控制值的影响关系．计算及分析结果表明，满功率抽水全失电导叶紧急关闭工况有可能成为上调最高水位的控制工况．     

潮州供水枢纽西溪电站水轮机过渡过程

叙述了对潮州供水枢纽西溪电站水轮发电机组甩负荷过渡过程的计算过程,核准了机组甩负荷时导叶前最大压力上升与机组速率上升,确定了甩负荷时导叶、浆叶的最优关闭规律。     

水轮机导叶两段关闭规律的优化研究

本文通过仿真计算优化了水轮机导叶两段关闭规律,分析了快关段的时间、开度以及总关闭时间对过渡过程的影响,这对在实际电站运行中选择合适的导叶关闭规律能起到指导意义。     

小型水电站水轮机导叶关闭规律的优化——以猴场水电站为例

以猴场水电站为例,探讨了小型水电站水轮机导叶关闭规律的优化。在水轮机组的GD2值因制造难度等原因不能加大时,采用导叶关闭的方法,通过优化导叶关闭规律,以满足水电站水力过渡过程计算的要求,从而可以有效地解决机组甩负荷后转速上升和蜗壳进口压力上升的问题。     

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。     

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.     

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。