凤滩水电厂AGC控制策略

详细介绍凤滩水力发电厂AGC控制策略实现方法，重点介绍修正等容量比例有功分配方法及采用的相应措施。程序设计原则是机组紧跟目标负荷的情况下，电厂机组在最佳效率下运行，同时减少机组开停机次数、有功调节频率和跨越振动区次数，从而减少机组磨损，兼顾了运行效率和机组运行安全。文中介绍的方法在电厂AGC正式纳入调度考核中将发挥重要作用。     

清江梯级水电厂AGC的工程实现

基于梯级水电厂的优化运行原则，综合考虑避免机组频繁启停、厂间联 合躲避振动区等因素，较为详细地分析了清江梯级水电厂自动发电控制(AGC)实现过程中必 须考虑 的工程化因素，提出了一种实用的梯级水电厂AGC优化运行算法，包括机组开停机和厂间负 荷分配算法。在此基础上设计的AGC软件已成功地应用到清江梯级水电厂中。     

远程集控模式下三板溪水电厂AGC方法与应用

建设流域梯级水电厂群集控系统是各流域公司加强在电力市场条件下竞争能力的必然选择,以追求梯级电厂群的综合利益最大化为目标。在介绍五凌公司跨流域水电厂群远程集控系统的基础上,重点研究了在远程集控模式下三板溪电厂的自动发电控制（AGC）方法,采用修正的等容量比例分配方法实现机组负荷的优化分配,详细介绍了机组根据水头自动躲避振动区的方法、机组跨越振动区策略、防多机组频繁调节策略等。目前,文中提出的AGC方法已在五凌公司跨流域水电厂群远程集控系统获得试运行,能安全地实现三板溪电厂有功负荷的远程优化分配,具有一定工程有效性。     

水电厂机组在AGC控制方式下开停机策略分析

对水电厂AGC控制系统的功能进行介绍，分析了水电厂机组在AGC调度控制方式下开停机方式，提出了在满足电网系统稳控装置的要求，不干扰AGC控制系统自动有功功率调整，尽量减少机组频繁跨越振动区等因素下的最优开停机策略。     

天生桥一级水电厂AGC振动区处理策略

一般情况下,自动发电控制(AGC)对于振动区的处理原则是避免机组运行在振动区.由于天生桥一级机组的振动区极为特殊,过大的振动区范围导致其可调范围较小,因此南方电网允许天生桥一级水电厂AGC可以短时间内运行在振动区.文中根据机组在振动区运行的累积时间或机组进入振动区运行的优先级,采取机组轮流进入振动区运行的策略,不仅可以有效避免对南方电网稳定断面潮流的影响,而且有利于电网的稳定运行.     

抽水蓄能电站AGC有功负荷优化分配策略的改进

当前,抽水蓄能电站的自动发电控制系统均采用等比例有功分配的方式,这样往往会致使高水头的水能资源没有得到充分利用。结合抽水蓄能电站机组的运行特性,建立了抽水蓄能电站自动发电控制系统有功负荷优化分配数学模型,根据模型的特点,提出了改进的双向动态规划在线并行解算的方法,该方法能够满足抽水蓄能电站自动发电控制的实时性要求。在此基础上,通过对全厂总有功负荷在机组间的优化分配,使全厂的总发电耗水率降低了1%以上,有效地提高了抽水蓄能电站运行的安全性及经济性。     

三峡右岸电站AGC功能设计及实现方法

介绍三峡右岸AGC运行模式、调度模式、调节模式以及各种模式实现方法，针对国内AGC调频方式难以给出确定的频差系数的问题，采用自适应自学习调频方法；对于超大型机组AGC有功调节的安全性问题，采用功率跟踪和功率补偿措施；负荷曲线方式引入分步调节算法，减少对电网冲击；对于电厂效率优化问题，采用修正等容量比例负荷分配措施。这些措施既提高了电厂运行效率，同时保证了电网安全，标志着国产监控系统AGC首次成功运用于700MW大型机组，为三峡右岸水电站自动运行提供有力保障。     

宝泉抽水蓄能电厂AGC/AVC的应用

抽水蓄能电厂自动发电控制（AGC）/自动电压控制（AVC）的总体要求是根据电网有功潮流和电网电压的变化,及时调整机组有功出力和无功出力,保证电网运行的安全性和经济性。文中从AGC/AVC系统结构、数据交换、有功负荷分配策略、电压控制和整体功能的实现方式等方面,介绍了宝泉抽水蓄能电厂AGC/AVC的特点,实现的技术方式、约束条件和特殊功能。     

AGC及其在天生桥一级水力发电厂的应用

介绍机组自动发电控制(AGC)的基本原理及功能,并结合机组自动并网带负荷、机组平均分配负荷、机组负荷调节分配、机组躲避振动区等4个试验,并介绍AGC在天生桥一级水力发电厂的应用情况。     

广州蓄能水电厂对于广东电网安全运行的重要性

介绍了广州蓄能水电厂机组对于广东电网安全运行的重要性，从发电和抽水的事例分析了调度员乐意直接控制广州蓄能水电厂机组，在系统出现大功率缺额事故时，广州蓄能水电厂为系统提供快速备用。     

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.