发电机空气间隙在线监测技术在三峡右岸电站的应用

水轮发电机定转子间气隙是一项重要的电磁参数,对水轮发电机空气间隙进行在线监测已成为水电厂状态监测的重要组成部分。本文以空气间隙在线监测技术在三峡右岸电站16号水轮发电机上的应用为例,从评价发电机气隙特性、检验发电机转子机械特性和磁极伸长状态、掌握发电机定子相对热膨胀规律、辅助机组异常振动分析等方面介绍了该技术的应用情况。现场应用表明,对水轮发电机空气间隙进行监测,可为指导新机组气隙调整、检验发电机制造安装质量、优化发电机结构设计提供依据,具有实际工程应用价值。     

水轮发电机空气间隙测量

本文介绍了已获得加拿大新型实用型装置专利的水轮发电机空气间隙监测技术和装置,重点在于说明这种装置的安装、操作技术和功能特点,以及它的实用性和可靠性。该装置以加拿大魁北克水力研究所研制的电容式非接触片状传感器为检测元件,突破了近年来各国一直致力于研究的价值昂贵的光纤测量的框框,取得了实质性的成果,并已在北美及巴西20多台水轮发电机上获得了应用,其中包括伊太普电站的70万千瓦的水轮发电机。文章还介绍了水电部机电研究所在推广应用该项技术成果中所进行的工作,目的在于在我国的大型水轮发电机上逐步建立相应的空气间隙监测装置。     

发电机定子热膨胀位移和磁极松动探讨

一、概述 大型水轮发电机的空气间隙在试运转及以后的运转中,由于种种原因都可能发生变化,这些原因包括设计,安装以及作用于定、转子结构部件电磁力及离心力、尤其与发电机定、转子部件结构有较大关系。运行中空气间隙是否均匀直接关系到发电机的电气、机械性能的稳定。     

通过调整发电机空气间隙值有效降低定子低频振动

介绍水轮发电机组定子低频振动在小修过程中，检修工期短，不具备吊出转子的情况下，在机坑内吊装单个磁极，改变磁极垫片厚度，从而改变发电机空气间隙值，来解决水轮发电机定子低频振动偏大问题，已在A电厂进行处理定子低频振动，取得了预期效果。     

节能型整体片式水轮发电机空气冷却器研发与应用

长期以来,水轮发电机空气冷却器采用传统的绕簧式结构,该空气冷却器制造工艺复杂、散热性差、散热管刚度弱、体积大、检修维护不方便等弱点,在总结国内外各类水轮发电机空气冷却器的设计、制造、安装、运行经验的基础上,借鉴当前汽车制造行业冷却器的特点,自行研发、制造出节能型水轮发电机空气冷却器。经过5年多现场实际运行的考验,其运行性能良好,为水轮发电机空气冷却改造和新电站空气冷却器的选用探索出了一条新路。     

水轮发电机空气冷却器泄漏检测装置设计与安装——以枕头坝水电站为例

鉴于水轮发电机安装的空气冷却器在投入运行后,空气冷却器存在漏水的风险,根据枕头坝水电站水轮发电机空气冷却器的特性,设计安装了空气冷却器漏水检测装置,经测试,检测装置合格,投入运行。     

瀑布沟水电站水轮发电机组在线监测分析系统的应用

介绍了瀑布沟水电站水轮发电机组在线监测分析系统的主要功能及其应用情况,重点对在线监测的摆度、振动、稳定性、发电机空气间隙评价等具体数据,进行了分析和机组故障判断的实际应用。     

水轮发电机轴电流的设备治理及效果分析

水轮发电机转子和定子不完全同心,定转子空气间隙不均匀,导致电机内磁路不对称或磁场畸变,引起磁通脉动,磁通脉动产生轴电压,在转子轴承～外壳的环路中形成轴电流,轴电流对发电机部件会造成一定的危害。因此,水轮发电机都要加装轴电流保护器,起到监视轴电流的作用。运行中,绝缘边缘、接缝部位的表面脏污会破坏绝缘性能,应定期检查和清擦发电机集电环、刷架,避免碳粉沉积降低正负两极绝缘性能而产生轴电流。     

一种新型的水轮发电机空气间隙测量装置

本文介绍一种新型的水轮发电机空气间隙测量ＡＧＳ，它不必配备复杂的数据采集单元，对间隙信号作前置处理后直接以０－１０ＶＤＣ或４－２０ｍＡ模拟量输出使现地盘面显示和按使用者要求进行计算机集中控制成为可能。     

水轮发电机空气间隙监测技术的应用

水轮发电机定、转子间的空气间隙是一项重要的电磁参数，如果空气间隙在安装或机组投运后出现不均匀，将会影响机组的运行性能，同时也直接反映了发电机在设计、安装和运行等诸方面存在的问题。目前我国只是在机组安装完成后，在静态工况下用简易的方法检验气隙值，但对机组运行中，以及机组在各试验工况下气隙会发生怎样的变化无法知道，为了全面了解发电机定转子气隙在运行中的变化，及早发现故障隐患，保障机组安全运行，恰浦其海水电站从加拿大维保公司引进了世界上先进的发电机空气间隙监测分析系统，通过在工程上的应用，表明该系统能够准确地测量各工况下的空气间隙值，能对发电机定转子结构做出全面评价，使业主对自己的设备有更为全面的了解，增强了验收依据，提高了验收质量。同时，该系统还将发挥长期效应，为电站实行状态检修提供科学依据。     

EXPERIMENTAL INVESTIGATION ON WAVE RUN-UP CHARACTERISTICS ALONG COLUMNS AND AIR GAP RESPONSE OF SEMI-SUBMERSIBLE PLATFORM

This article mainly concentrates on a large-volume drilling semi-submersible platform,aiming to reveal wave run-up characteristics along square columns and give the relationship between air gap distributions and wave parameters.The tests with fixed model were conducted firstly on its encountering a series of monochromatic waves.A wide range of wave slope (H /L) were selected to investigate the air gap response in detail.As can be seen,larger wave steepness will generally cause smaller air gap in the same wave period,which indicates nonlinear effects of incoming wave can amplify wave elevation.Model tests with mooring condition were also conducted in the same wave conditions.As was expected,the maximum relative wave elevation reduces obviously compared with the fixed one.However,wave shape close to columns show higher harmonic characteristics due to interaction between waves and the columns of semi-submersible platform.Meaningful conclusions from the model tests are drawn in this article,which is helpful in air gap design of floating offshore platform to a certain extent.In addition,the experimental results will provide an important reference for further research on validation and update of theoretical models of air gap.     

高水头船闸阀门顶缝空化切片试验研究

针对日益严峻的高水头单级船闸阀门顶缝空化问题,采用能够真实反映缝隙流特性的1:1切片模型试验,研究阀门顶缝空化特性及门楣自然通气防空化机理。研究表明,随着空化的发展,缝隙段依次发生喉口跌坎空化、主流中心空化和阀门面板空化,缝隙段负压区不断延伸,直至整个缝隙段达到稳定的-10 m水柱负压,压力脉动很小;门楣自然通气通过增加缝隙段压力,消除主流中心空化和阀门面板空化,抑制喉口跌坎空化。当采用门楣自然通气措施后,缝隙段压力稳定在-2 m水柱左右,空化消失,缝隙段水流脉动压力增大;缝隙段压力与单宽通气量近似二次多项式关系,通气量极值对应的缝隙段压力约-2 m水柱,此时缝隙段压力与通气量达到平衡状态,当缝隙段压力逐渐升高时,门楣通气量逐渐降低,直至自然通气停止。     

复合防渗衬垫缺陷渗漏量计算方法探讨

复合衬垫系统的渗漏量是评价衬垫系统的一个重要指标,笔者假定膨润土中流线垂直向下和不考虑土工膜与土工织物之间空隙的影响,根据水流的连续条件,利用解析的方法,对土工膜上存在孔洞缺陷的土工膜＋GCL复合衬垫系统的缺陷渗漏量进行数值模拟。然后通过试验验证,得出该计算模型可以作为存在孔洞缺陷的土工膜＋GCL复合衬垫系统渗漏量的一个计算手段。     

高水头船闸反弧形阀门门顶缝隙流特性及其应用

本文介绍了高水头船闸门顶缝隙流的１:１切片模型试验及其机理；阀门段廊道减压模型中的通气部位比较试验；门楣通气方式以及两座船闸门楣自然通气措施的实际应用情况。原型观测成果表明，门楣自然通气不仅可减免顶止水缝隙空化，而且可抑制阀门底缘空化，改善船闸运行条件。     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF THERMAL-HYDRAULIC PERFORMANCE OF A CIRCULAR TUBE WITH EDGEFOLD-TWISTED-TAPE INSERTS

Three-dimensional numerical simulations and experiments were carried out to study the heat transfer characteristics and the pressure drop of air flow in a circular tube with Edgefold-Twisted Tape (ETT) inserts and with classic Spiral-Twisted-Tape (STT) inserts of the same twist ratio. The RNG turbulence model for mildly swirling flows, the enhanced wall treatment for low Reynolds numbers, and the SIMPLE pressure-velocity method were adopted to simulate the flow and heat transfer characteristics. Within the range of Reynolds number from 2 500 to 9 500 and the twist ratio y from 5.4 to 11.4, the Nusselt number of the tube with ETT inserts is found to be 3.9% ? 9.2% higher than that with STT inserts, and the friction factor of the tube with ETT inserts is 8.7% ? 74% higher than that of STT inserts. The heat enhancement is due to higher tangential velocity and asymmetrical velocity profile with the increase and decrease of the periodic velocity within an edgefold length. It is found that main factors affecting the heat transfer of ETT inserts are the twist angle and the gap width between the tube and inserts. A larger twist angle leads to a higher tangential velocity, and larger Nusselt number and friction factor. The thermal-hydraulic performance slowly decreases as the twist angle increases. The gap width between tube and inserts has a significant influence on the heat transfer, while little influence on pressure drops. The thermal-hydraulic performance increases in average by 124% and 140% when the gap width reduces from 1.5 mm to 1.0 mm and 0.5 mm. The larger the gap width, the higher velocity through the gap will be, which would reduce the main flow velocity and tangential velocity. So a small gap is desirable. Comparing experimental and numerical results at variable air flow and tube wall temperature, the numerical results are found to be in a reasonable agreement with the experiment results, with difference of the Nusselt number in a range of 1.6% ? 3.6%, and that of the friction factor in a range of 8.2% ? 13.6%.     

天生桥二级水电站6号发电机定子铁损及温升试验

水轮发电机定子铁芯是由硅钢片叠合组装而成。在叠片结束后，必须检查片间是否有气隙或松动，并检查片间绝缘及穿芯螺栓与硅钢片之间的绝缘等情况。如果存在气隙、权动及绝缘不良等情况，在运行过程中出现振动和局部过热，从而引起定子线棒的绝缘破坏，这对发电机安全运行将造成严重威胁。所以对新叠片或修理过的铁芯必须进行铁芯损耗试验（简称铁损试验），测定铁芯单位重量的损耗，测量磁轭和磁齿的温度，检查各部温升是否超过规定值。从而综合判断叠片的情况是否符合要求。     

坝体接缝的线性互补模型及横缝对拱坝工作性态的影响

借助罚因子建立了坝体接缝的增量本构模型，导出了互补虚功方程，采用有限元离散建立了坝体接缝的线性互补模型，该模型可以较好的反映接缝的接触条件，并提高计算效率。结合小湾拱坝对横缝及其初始间隙对拱坝工作性态的影响进行了分析，结果表明，如果横缝没有初始间隙，则它对坝体工作性态没有多大的影响，但当横缝存在初始间隙时则有较大的影响，坝体的应力和位移均随着初始间隙的增大而增大。     

宽戗堤截流龙口水力特性研究

通过模型试验对宽戗堤截流龙口范围内的水流特性进行系统研究。试验结果表明:当宽戗堤宽度与总水头的比值B/H0在3.1~5.7之间时,随着戗堤宽度的增加,戗堤表现出宽度效应,龙口内水面形态由单降型流态变为双降型流态,龙口中下部流速降低明显,龙口前壅水高度逐渐增大;当B/H0>5.7时,戗堤的宽度效应减弱;当B/H0<3.1时,龙口区域没有宽度效应。运用多元回归分析,初步研究了各因素对宽度效应的影响。     

The hydraulic characteristics of end-dump closure with the assistance of backwater-sill in diversion channel

The river closure is a key step in the water dam construction, and the end-dump closure is a general way to cut off the river flow. The hydraulic characteristics at the closure gap are the main factors which affect the extent of closure difficulty. A method is proposed to reduce the difficulty of diversion channel closure by pre-building a closure structure called the backwater-sill at the downstream toe of the closure gap to change the flow pattern at the closure gap. The results of the physical model test and the threedimensional numerical simulation indicate that the backwater-sill has the effects of raising the water level at the downstream toe of the closure gap, decreasing the water surface gradient, and reducing the closure drop and the flow velocity at the closure gap. The schemes with different dike widths, different closure gap widths, and different backwater-sill widths and heights are simulated. The results show that the height of the backwater-sill is the key factor affecting the hydro-indicators at the closure gap, while the influence of the dike width, the closure gap width or the backwater-sill width can be ignored. The higher the backwater-sill is, the lower the hydro-indicators will be. Based on the numerical simulations and the physical model tests on the hydraulic characteristics at the closure gap of the backwater-sill assisted closure, the hydro-indicators and its calculation method are proposed to provide a theoretical support for the river closure.