风储联合调频中储能的容量优化配置

从风电场自身的一次调频能力出发,将储能控制与风电机组变桨距控制相结合,采用机会约束规划处理可信度和运行成本间的关系,考虑储能全寿命周期成本,以风储联合调频运行成本最小为优化目标,建立机会约束规划模型,利用蚁狮算法进行求解得出风电场储能功率和容量的最优配置方案,通过算例验证,模型可降低系统一次调频总成本和所需配置储能容量。     

论风机电气设备检修方案的可行性影响因素

对双馈风力发电机组变频器经常出现的故障进行诊断分析和处理,汇总故障检查和处理过程,找出目前风力发电机组电气设备故障检修工作的主要影响因素,同时风机设备逐步完成厂家代理检修维护阶段,交由风电场自主进行检修维护工作。笔者结合目前风电场实际情况,对风力发电机组电气设备检修维护方案影响因素进行分析,提出实现风电场风力发电机组电气设备检修工作方案设计的几点看法。以帮助风电场提高风力发电机组日常检修维护工作的合理性和经济性,使风电场风力发电机组检修维护工作实现降本增效。     

变速恒频双馈电机风电场电压控制策略

提出了一种基于变速恒频双馈电机的风电场电压控制策略,该策略以风电场出口升压变压器高压侧电压为控制目标。介绍了该控制策略的总体结构,阐述了风电场高压侧电压控制的原理,并考虑风电场无功功率极限,研究了无功功率控制、分配和故障情况下紧急电压控制方案。针对风速扰动和电压骤降2种情况进行了仿真。仿真结果表明,所提出的控制方案与功率因数控制和传统的电压控制策略相比可以明显地提升风电场电压水平,且无需高压侧信号、经济有效。     

基于全寿命周期成本的风电场工程规划优化设计研究

在大规模风电场工程规划设计中,如何优化电气系统设计方案,为风电场项目的科学决策提供依据,是风电场总体规划设计所面临的问题.运用全寿命周期成本管理的方法,对大规模风电场的总体规划设计进行了优化.通过综合技术经济比较,验证了总体规划设计方案初投资额的大小并不能代表其经济上的优劣,只有项目全寿命周期成本最低的方案,才是最为经济的方案.     

浙江省农村生活污水处理工艺比较研究

对浙江省内常用的农村污水处理工艺进行了总结归纳,并应用浙江省市政工程定额标准,建立了十种工艺五种典型规模的费用模型,进行全生命周期成本分析。以100m3/d为例,分析了十种不同工艺的费用构成,并计算了单位水量初期投资、运行成本、总成本三项费用,作为浙江省农村生活污水处理工艺选择和投资估算的依据。     

海上风电场建设成本及风险分析

与陆上风电场相比,海上风电场建设成本大大增加,主要体现在风电机组设备成本的增加,工程前期、勘探、设计费用的增加,附属工程增加引起的投资增加,施工费用的增加,运行维护成本的增加等几方面.从风资源的准确性和风电设备质量两方面对海上风电场的工程风险性进行了分析,并给出了合理化建议.     

小型排涝泵站机电设备的维护优化方案

为解决泵站维护优化问题,基于电子表格开发一个决策系统,用于估算设备的运行成本、故障分布参数和稳定性.研究目标是在较长计划期内,确定系统的最优维护和更换方案.通过数学规划软件来最小化总成本函数,同时满足系统稳定性的阈值,从而在每个周期中对系统做出最优决策.为了验证模型的准确性,对其有效性进行了检验,结果证明模型给出的方案...     

风电场接入系统方案的研究

以富川龙头风电场一期工程为研究对象,在对富川县进行电力需求预测及电力平衡的基础上,分析了龙头风电场的送电方向,提出了龙头风电场接入电网的两个方案。经技术和经济比较,得出龙头风电场接入系统方案。     

大型风电场暂态故障对电力系统稳定性影响研究

为探究大型风电场出现暂态故障时对电力系统产生的影响,以某拟建大型风电场为研究对象,建立了基于异步风力发电机组的风场模型并对3种故障情景进行模拟。结果表明,当风电场发生短路故障时,电压波动引起功率波动,进而引发系统产生频率振荡,影响系统的稳定性。鉴于此,提出在风电场加装频率稳定设备,该措施可在一定程度上改善系统的稳定性。     

双馈风电机组风电场并网故障特性

利用PSCAD软件构建了双馈风电机组风电场仿真模型,对可能造成双馈风电场并网故障电流幅值的主要因素(投运机组数、Crowbar电路及风速)进行研究分析,再对双馈风机故障电流频率特征进行分析。仿真模拟研究了在风电场联络线上距风电场30%处单相/双相接地不对称故障,结果显示故障电流/电压对风电场联络线的保护影响很大,可能会造成元件的误选以及距离/纵联保护的误动作。对构建的单个风电场模型进行了仿真结果表明接地短路故障可能会造成相邻风电场的连锁脱网事故,危及电网安全。     

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。     

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.     

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。