基于STATCOM的低压配电网电压不对称系统的电压波动控制研究

针对低压配电网电压不对称时负载侧电网电压的波动情况,传统的基于瞬时无功功率理论的无功电流检测方法已经不能满足静止同步补偿器(STATCOM)的要求,因此,在补偿不平衡负载时,提出了一种改进的低压配电网电压不对称系统的STATCOM的控制方法。该方法通过产生一个与负载无功电流分量大小相等、相位相反的输出电流来达到补偿的目的。STATCOM采用双环控制,其中内环为电流控制部分,外环为电压控制部分,通过外环控制来使得直流侧电压达到指定值,同时将该信号作为有功电流控制环的控制指令,然后将直接检测出来的负载侧无功电流基波分量作为无功电流控制环的指令,实现快速准确补偿。笔者还利用MATLAB软件进行了仿真研究,仿真结果表明,改进后的STATCOM控制方法能更有效地实现由不对称负载引起的电压波动的抑制效果。     

±20 Mvar STATCOM阻尼控制器输入信号选择研究

以在中国河南省投运的首台±20 Mvar STATCOM的控制系统设计为背景，研究了采用不同输入信号时对可控性和可观性的影响，指出线路有功潮流并不是最佳的STATCOM稳定控制输入信号，建议选择经过STATCOM输出电流和当地短路阻抗补偿的电压信号作为阻尼控制器的输入。该方法简单实用，已在±20 Mvar STATCOM中实施。     

SVC与STATCOM联合运行协调控制设计与仿真

针对静止无功补偿器（SVC）装置无法抑制电压闪变的缺点，提出了一种新型SVC与静止同步补偿器（STATCOM）构成的混杂装置以及基于模糊预测的联合运行方案，即利用小容量STATCOM抑制闪变配合大容量SVC补偿无功。对于抑制电压不平衡问题，探索了SVC分相控制的实现方法和效果。对含有混杂装置的单机无穷大系统的仿真结果验证了协调控制策略的有效性以及不平衡控制方法的正确性。     

STATCOM控制的电力系统稳定性分析

基于哈密顿系统理论，将含有STATCOM的简单电力系统表示为标准的哈密顿系统，推导了该系统的哈密顿函数，并证明了所得到的哈密顿函数可作为判断系统稳定性的Lyapunov函数。根据该函数，提出了STATCOM控制的电力系统的暂态稳定分析新方法。对含有STATCOM控制的简单电力系统的数值仿真结果证实了这一方法的有效性。     

±10 kvar静止同步补偿器的动模实验研究

介绍了±10 kvar静止同步补偿器(STATCOM)的动模实验结果，该装置为即将投运的 ±20 Mvar STATCOM原型。实验结果证实STATCOM具有快速的无功调节能力，可以有效地 进行负荷无功补偿和电压调节。通过维持传输线上某点的电压，还可以提高系统的静态稳定 极限。     

基于FPGA的静止补偿器PWM脉冲发生器设计

研制了基于现场可编程门阵列（FPGA）实现的、用于±500 kvar静止补偿器（STATCOM）的PWM脉冲发生器。该脉冲发生器通过接口单元接收DSP写入的PWM脉冲宽度数据，然后产生PWM波形，其工作不受DSP影响。同时介绍了脉冲发生器的基本原理、硬件构成和实现方法。该脉冲发生器已应用在工业和试验运行的±500 kvar STATCOM中，实际运行经验表明，该脉冲发生器精度高、可靠，可解决非对称和无功控制不平滑问题，而且所研制的脉冲发生器也适用于其他类型的逆变装置。     

STATCOM与发电机励磁的协调控制

针对单机无穷大系统，建立了包含静止同步补偿器（STATCOM）的状态空间模型，应用给定信息结构约束下的最优控制理论和算法，设计了4组STATCOM与发电机励磁的协调控制器。它们的控制规律分别是：状态反馈的完全分散协调控制、输出状态反馈的完全分散协调控制、STATCOM处可以反馈机组角频率偏差的特定信息结构下的LQ协调控制、全状态反馈的集中型最优控制。仿真结果表明，与独立设计的AVR/PSS励磁控制器和电压偏差PI调节型STATCOM控制器相比，上述4组协调控制器能更加有效地提高系统暂态稳定性能。同时，完全分散信息结构的状态和输出反馈控制的控制性能稍次于其他两种协调控制规律，但由于它们实现代价低、可靠性高，更易于实际应用。     

STATCOM应用于2010年华中电网的初步研究

随着三峡电站投入运行，2010年时华中电网的暂态电压稳定问题越发严重。文中利用清华大学提供的静止补偿器（STATCOM）的数学模型，并采用中国电力科学研究院的电力系统综合分析程序，对STATCOM接入华中电网进行了技术可行性仿真研究。所得结论为STATCOM在中国的产业化提供了可行性参考。     

STATCOM应用于2000年华中电网的仿真研究

以华中电网2000年网络结构为背景，研究了河南省电力局与清华大学联合研制的±20 Mvar静止补偿器（STATCOM）提高电压稳定性的能力，并讨论了STATCOM的安装点和控制点的选择原则，得出了相应的结论。这些仿真结果对STATCOM产业化有一定参考价值。     

STATCOM在上海电网中的应用仿真

上海电网随着负荷增长和网架结构的变化，电压问题日益突出，尤其是黄渡分区电网，缺少动态的电压支撑，不能满足电网安全运行的需要。文中将新型的动态无功补偿装置STATCOM应用于黄渡分区电网，进行了大量的仿真分析，并对不同的安装容量和安装地点进行了详细的比较分析。仿真结果表明，安装STATCOM装置将对黄渡分区电网电压起到较大的支撑作用。     

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。     

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。