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安装了分相式高压并联电抗器的高压输电线路,在线路发生单相接地故障而断路器单相跳闸瞬间,输电线路和高压电抗器处于缺相运行状态。如果高压电抗器匝间保护的电压采样取自母线TV二次侧,匝间保护在一次设备非全相运行时将会误判成区内故障而动作跳闸。文章根据一起330 kV线路单相瞬时性故障引起电抗器保护装置的匝间保护误动作、造成线路两侧断路器三相跳闸事件,分析了高压电抗器处于各种非正常情况下匝间保护动作原因,指出为防止电抗器非全相运行时匝间保护误动作应采取的措施。 相似文献
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针对带并联电抗器的超高压输电线路,研究了故障后线路断开相并联电抗器与中性点小电抗上的电压特性,发现在永久性故障时,无论是金属性接地还是经过渡电阻接地,断开相并联电抗器上电压与中性点小电抗上电压的比值总是大于瞬时性故障时两者的电压比值。基于上述结论,提出了超高压带并联电抗器输电线路单相自适应重合闸故障的电压判别方法。理论分析和EMTP仿真表明,该判别方法简单、有效,能可靠实现超高压输电线路上的单相自适应重合闸。 相似文献
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针对无并联电抗器补偿的高压及超高压输电线路,分析了采用自适应分相重合闸对机组轴系 扭振和系统暂态稳定的影响。研究表明,从对轴系扭振和系统暂稳的影响来看,在大机组电 厂的高压出线上采用自适应分相重合闸是可行的。 相似文献
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丁文发 《水电自动化与大坝监测》1997,21(5)
针对500 kV输电线路保护装置的选型问题,简述了广东电网500 kV线路保护的使用情况 ,分析了国外高压保护产品在国内电网运行中存在的缺陷和问题,叙述了国产保护原理的先 进性、适应性以及国产化、微机化500 kV线路成套保护配置方案。 相似文献
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我国目前500千伏电力系统中,线路断路器部装有合闸电阻,作为操作过电压保护的第一道防线,避雷器作为保护的第二道防线。在漫湾500千伏GIS引进与外商谈判过程中。ABB公司提出取消合闸电阻的建议,并提出书面研究报告。昆明水电院同时委托电科院对此进行了计算和分析。近几年来随着氧化锌无间隙避雷器的发展和国外500千伏电网运行的新经验,提出了仅用氧化锌避雷器限制操作过电压取消合闸电阻的新观点。本文介绍主要情况并结合漫湾实际,提出个人的初步想法,供有关方面参改。 相似文献
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地方电网孤立运行的水电站,系统装机容量小,在长距离小负荷110kV高压供电时,由于线路电容效应,末端电压升高。实践证明采用线路并联电抗器是最好办法,有利于提高输电能力及系统运行的稳定性,运行方便灵活。现就农一师西大桥水电站至农三师小海子图木休克110kV输变电工程(简称西图输变电工程)安装两台10kV线路并联电抗器运行一年来所遇到的实际问题。 相似文献
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提出一种适用于两端带并联电抗器的超高压输电线路的单相自动重合闸永久故障识别方法。输电线路发生单相故障两端跳闸后,利用电流差动保护原理对断开相两端的电流量进行比较,将瞬时故障视为区外故障,永久性故障视为区内故障,根据判据判断故障为永久性或者瞬时性,以决定是否重合闸。ATP仿真结果表明该方法能准确区分永久性和瞬时性故障,判断可靠、耐过渡电阻能力强。 相似文献
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提出在连接西北主网与新疆电网的哈密—永登750 kV输电通道上配置可控高压电抗器,提高潮流调控能力,更好地限制工频过电压和潜供电流。基于2010年和2020年的西北电网750 kV输电系统运行方式,分析了可控高压电抗器对系统长期运行经济性和动态品质的影响,评估了可控高压电抗器所能带来的经济效益。结果表明,可控高压电抗器能改善系统的稳态、机电和电磁暂态特性。指出:综合系统运行经济性、安全性和控制灵活性等方面因素,可以将可控高压电抗器配置在750 kV张掖站。 相似文献
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介绍了龙滩水电站500 kV GIS 4/3接线方式下,线路保护与重合闸之间的配合方法,对按断路器配置重合闸的一些主要问题进行了探讨,对一些设计不足之处提出了修改意见,供同行参考. 相似文献
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自动重合闸装置在电力线路中有着广泛的应用,尤其是当电力线路发生瞬时性故障时,继电保护跳开断路器后由自动重合闸装置进行重合,重合成功后恢复正常供电,对减少停电时间,提高供电可靠性具有重要意义。在110 kV及以下输电线路系统中,最常见的是单侧电源输电线路及双侧电源输电线路的三相自动重合闸。本文主要针对这两种情况下的新型微机型三相自动重合闸装置的基本原理及应用进行讨论。 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
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.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
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. 相似文献
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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。 相似文献