量测量的时延差对状态估计的影响及其对策

监控和数据采集 (SCADA) 系统的量测量没有统一的时标，更新周期长，而且时延较大。同步采样的相量测量单元（PMU）正成为电力系统中另一种重要的数据采集装置，它可以反映动态响应且时延较小；由于带有精确时标，即使通道传输存在时延也能保证时间断面的一致性。为在状态估计中协调这两种量测量，处理各量测量不同的时延，建立了SCADA量测时延的均匀分布模型，分析了各量测数据所反映的时间断面不一致性对状态估计精度的影响，提出了对时延不同的量测量的处理方法。通过对IEEE 14节点电网和一个366节点的实际电网的仿真，验证了该方法的有效性。     

明渠时差法流量计流量计算方法分析研究

目前国内外对明渠时差法流量计流量计算方法研究较少,对时差法流量计流量计算方法进行系统完整的研究,从时差法测验原理、理论标定系数k1的计算方法、水道断面面积的计算方法、现场标定系数k2的计算方法,详细阐述了明渠时差法流量计流量计算方法,提出了线性插值计算理论标定系数k1的方法。以南水北调输水断面运河站为例采用线性插值计算理论标定系数k1的方法,进行时差法流量计流量计算,计算结果与流速仪法对比显示两者一致性较好,误差可控。进而为工程技术人员提供参考;为国产化时差测流装置提供重要技术支撑;为我国重点通航河道和低流速实时在线流量监测提供技术保障。     

基于PMU的分布式电力系统动态状态估计新算法

随着电力系统的发展，区域电网互联，形成更大的系统。各区域电网相对独立，且有各自相对独立的调度中心。为适应这种分区管理模式，状态估计应采用分布式并行算法。在动态估计扩展Kalman滤波算法的基础上，结合搭接式分布并行算法，提出了一种基于相量测量单元（PMU）的分布式电力系统动态状态估计新算法。该算法利用少量PMU测点，真正实现各子系统的并行计算，避免了原算法进行串行等待的过程。并结合量测数据预处理、对雅可比矩阵加权等方法，加快了计算速度，提高了数值精度和稳定性。最后给出了IEEE 14节点的仿真结果，验证了该算法的有效性及优越性。     

基于相量量测的电力系统线性状态估计

分析了相量量测装置的量测误差情况，指出了相量量测参与状态估计计算的必要性。在完全使用相量量测的情况下，给出了基于直角坐标系的实数形式的电力系统线性量测方程和相应的线性静态状态估计算法。对负荷预报加潮流计算的系统状态预报方法进行改进，通过对误差协方差阵计算公式的推导与简化，提出了新的预报误差协方差阵计算公式，并将其与线性量测方程相结合，提出了基于相量量测的线性动态状态估计算法。最后讨论了线性状态估计算法的使用条件，并采用IEEE 30节点系统对提出的算法进行了验证。     

断面法计算河道冲淤量方法中断面间距探讨

断面法计算河道冲淤量原理简单、程序简洁,是最常用也是最广泛使用的方法之一,但重要计算参数"断面间距"不论从定义或是量算尚无统一标准,导致断面法计算河道冲淤量存在一定误差。以长江沙市河段为例,对断面法与体积单元法计算结果进行比较,可认为断面间距并不是断面法计算河道冲淤量方法中的必要参数。     

计及PMU的混合非线性状态估计新方法

提出一种将同步相量测量单元（PMU）的直接电压相量量测变换为间接支路电流量测，并与监控与数据采集（SCADA）量测量一起进行混合迭代的非线性状态估计方法。对构造等效电流修正量而带来的间接量测误差进行了详细和定量的分析，并对该混合估计算法的精度进行了定性分析和定量计算。理论分析和算例表明，该方法可以获得较高的估计精度，在收敛次数和滤波效果上也有所改进。     

电力系统的状态估计和稳定性分析

电力系统的状态估计和可靠度分析对于大电网安全稳定是非常重要的，现代控制系统理论为电力状态估计提供了理论依据和方法。本文结合四川电网的现状进行了分析，提出了电网在今后的改造和发展中应注意的问题和建议。     

基于改进模型预测控制的分布式储能辅助调频控制方法

为更好改善电网频率特性，发挥分布式储能的快速响应优势，提出基于改进模型预测控制的分布式储能辅助调频控制方法。首先，基于动态矩阵控制(dynamic matrix predictive control, DMC)思想，引入了一种新的综合状态空间模型，将增量控制输入视为阶跃输入，设计了以减小稳态误差为目标的MPC优化目标函数。其次，建立了控制信号的选择规则，在预测模型的滚动优化过程中对多步控制信号进行动态调整，形成考虑延时和丢包的延迟补偿机制，并在此基础上给出了系统稳定的充分条件。最后，在不同工况下进行仿真，与基于传统MPC的储能辅助调频方法相比，对所提策略的有效性进行了验证。结果表明：本文提出的改进MPC策略提高了分布式储能调频对通信延时的鲁棒性，提高电力系统的安全性，同时减小了系统超调量和稳态偏差。     

配网补偿电容器故障监测研究

无功功率补偿电容器在电力供电系统中处在一个不可缺少的重要位置.电网上应用的无功补偿电容器,在电力供电系统中起提高电网的功率因数的作用,无功补偿可以降低供电变压器及输送线路的损耗,提高供电效率,改善供电环境.所以保证配电网上的补偿电容器组安全、可靠地运行是非常重要的一项技术,对于保证整个电网的安全正常运行起着至关重要的作用.本文通过对比几种电容器状态监测手段的经济性、和实用性等方面出发,设计了一种比较科学的电容器组状态监测方法.     

珠藏洞隧道施工安全监测与评价

为了保证谷城至竹溪高速公路珠藏洞隧道开挖过程中的施工安全,在优化围岩变形的监测方案与预警方法的基础上,对典型监测断面位移量测数据进行了回归分析。分析结果表明,隧道监测断面拱顶沉降和边墙收敛位移累积值均明显小于警戒值,隧道开挖后围岩稳定性较好;隧道围岩变形量和稳定时间与隧道埋深和地质条件密切相关,埋深越大或岩体质量越差,变形越大。     

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。