基于改进Jacobian-Free Newton-GMRES(m)的电力系统分布式潮流计算

为了提高互联电网分布式潮流算法的实用性，应尽可能减少协调计算中的交换信息。文中采用隐函数方式表示分布式潮流的边界协调方程，并采用具有自适应预处理能力的Newton-GMRES(m)方法构建分解协调算法。该方法具有Jacobian-Free特性，协调计算中只需要交换边界节点状态信息。以IEEE标准系统和大规模实际系统为算例的测试结果表明，新的分布式潮流算法具有较高的收敛性，数据交换接口简单，实用性强，适合于求解连续变化的分布式潮流问题。     

小扰动稳定域微分拓扑学性质初探:(一)小扰动稳定域非凸边界和空洞现象示例

对电力系统小扰动稳定域的微分拓扑学性质进行了初步探讨。首先，简单回顾了小扰动稳定域的相关定义、边界组成及其性质；然后，给出一种基于优化过程实现对小扰动稳定域Hopf分岔界面追踪的算法；最后，利用一个简单的3节点系统，示例了小扰动稳定域边界面非凸和内部存在封闭不稳定(空洞)区域的现象，并对小扰动稳定域内部空洞区域随系统参数变化的规律进行了研究。该工作对于进一步深化对电力系统小扰动稳定域微分拓扑学性质的研究具有一定帮助。     

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。     

电力系统电压稳定分区和关键断面的确定

电网的关键断面能够体现电力系统运行的薄弱环节，是电网稳定性分析和监视的重点对象。文中针对电压稳定研究的需要，提出了电力系统节点间的连接关系和联系紧密程度的评价方法，建立与电网网架结构相对应的图模型，然后引入了谱聚类算法，进行输电网分区分析，可层次递推地给出系统的合理分区，继而可确定各分区间的关键断面。通过IEEE 14节点算例和河南电网的应用分析结果表明，该算法能够准确有效地确定系统的电压稳定关键断面。     

基于潮流方程组拼接模式的互联系统分布式潮流计算

目前互联电力系统使用集中式和分布式建模2种思路来获得全局广域潮流解，2种思路各有优缺点。文中力图将两者的优点结合起来，提出了一种带有集中式特点的分布式潮流拼接算法。该算法将各子网的导纳矩阵、节点注入功率向量、节点类型信息向量拼接起来构成全局潮流方程组，据其在某个子网侧计算出全局潮流后，将其余子网的潮流数据传送回去从而获得全网的分布式潮流。拼接算法无需进行全网一体化建模或模型拼接，各子网间亦无需进行协调迭代计算，但所求得的潮流计算结果却与一体化建模时完全一致。在IEEE 9节点系统上进行的数值仿真实验表明了所述拼接算法具有较突出的优势。     

区间不确定信息下电力系统安全性的快速评估算法

计及高压输电网络中的不确定因素，提出了区间负荷下快速评估电力系统安全性的新算法。该算法对传统分支定界算法进行了改进，证明了电力系统最小切负荷问题的负荷边界特性，将双层规划模型的求解转化为少量线性规划模型的求解。改进后的分支定界算法能够快速、准确地求解基于双层线性规划的区间至多切负荷模型，得到区间负荷下计及发电机的可调作用时，基于直流潮流模型的系统最小切负荷量的最大值。新算法的计算速度大大优于求解同类问题时所用的蒙特卡罗模拟法和分支定界法，精度较高。6节点和46节点系统算例的计算结果验证了算法的正确性和有效性。     

对Normal Form 变换的多值性的分析与研究

简单介绍了Normal Form方法稳定域边界理论及其在电力系统中的应用，对用Normal Form方法确定电力系统的暂态稳定域边界理论提出了相关的算法：即由原点映射的唯一性确定非线性映射的初始点；从对单机无穷大系统的分析可以了解到非线性变换的多值映射的几何意义。6机22节点系统算例验证了该算法的可行性。     

基于Jacobian-Free Newton-GMRES(m)方法的电力系统分布式暂态仿真算法

分布式暂态仿真是实现市场环境下互联电力系统在线一体化仿真分析的有效途径。文中研究了电力系统分布式暂态仿真计算模型，提出了基于Jacobian-Free Newton-GMRES(m)方法的协调求解算法。该算法只需要交换边界母线状态信息，接口简单，实用性强。为了提高算法收敛速度，减少协调求解所需通信次数，提出了自适应预处理和连续修正预处理矩阵、预估边界条件初值及多时步同时协调等改进方法并将其应用于新算法中。测试结果表明，新的暂态仿真分解协调算法收敛快，通信次数少，非常适合在基于广域网络的分布式环境中实现。     

基于稳定域边界二次近似的故障临界切除时间估计

基于故障后电力系统稳定域边界的二次近似来估计临界切除时间。在计算中，通过二次项系数矩阵分块来降维计算二次项系数，大大降低了二次项系数的计算量。临界切除时间由持续故障轨迹和主导不稳定平衡点(CUEP)所决定的稳定域边界二次近似的交点确定。在IEEE 3机9节点系统和新英格兰10机39节点系统中的仿真表明了该方法的有效性，特别是对非发电机节点故障临界切除时间的估计精度较高，能够满足工程要求。     

暂态稳定分布式仿真计算的改进算法

电网互联和电力系统市场化发展趋势对暂态稳定分布式计算提出了要求。文中研究了电力非线性网络暂态稳定分布式仿真算法的计算效率问题，指出算法的瓶颈主要是子系统边界值的迭代求解计算，提出了改善非线性网络分布式求解效率的交接变量估计法，进行了数值验证，并与适于线性网络求解的并行处理方法、已有的电力网络暂态稳定初值估计法和交接变量调节法进行了比较。数值实验表明，文中提出的方法可在较大程度上稳定地改善暂态稳定分布式仿真分析的计算效率，与电力市场条件有一定的适应性。     

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。