牵引变压器绝缘在线监测技术研究

牵引变压器是牵引供电系统的重要组成部分之一,监测牵引变压器运行状态,及时地发现牵引变压器内部故障,对于确保高速铁路安全运行具有重要的意义。DGA技术是检测变压器潜伏性绝缘故障的有效措施之一。文章基于DSP技术,设计了一套牵引变压器DGA在线监测系统,经过实验室多次模拟试验,系统数据理想可靠。     

电铁牵引站V/V接线变压器数学模型及其短路计算分析

通过建立电气化铁路牵引站V/V接线变压器数学模型,对其不对称供电结构的电网进行故障计算分析,探讨对电网保护装置运行的影响。     

变压器绝缘油气相色谱的异常分析

变压器是电力系统重要的电气设备，也是电力系统事故较多的电气设备，其运行状态直接影响系统的安全性水平。为了提高供电的可靠性，及早发现变压器的潜伏性故障，加强对变压器运行状态的监控至关重要。按照规程要求，定期对变压器绝缘油进行气相色谱试验，认真分析试验结果，能非常灵敏、有效地发现变压器内部的某些潜伏性故障。     

基于EEMD样本熵的直流牵引网故障电流识别

针对地铁直流牵引网的振荡电流容易引起继电保护系统频繁误动的问题,提出一种结合总体平均经验模态分解(ensemble empirical mode decomposition,EEMD)和样本熵的直流牵引网振荡电流与短路故障电流识别方法。利用EEMD方法对直流牵引网的馈线电流信号进行分解,求取各固有模态函数(intrinsic mode function,IMF)分量的样本熵值,并将计算结果求和,进而获得反映直流牵引网运行状态信息的特征量。通过对典型馈线电流信号进行分析计算,可知EEMD和样本熵相结合的特征提取方法可以有效地区分直流牵引网振荡电流与短路故障电流。算例分析验证该方法的有效性。     

液压牵引采煤机牵引部常见故障的分析与处理

对煤矿液压牵引采煤机工作中常见的原因及处理方法进行了总结，为今后牵引部故障的诊断和排除提供了可靠的依据。     

电力系统变压器故障原因分析及处理方法研究

在电力系统中,变压器是重要的电力设备。变压器的稳定运行是保障电力系统安全生产的基础,变压器出现故障将严重影响供电的可靠性和电力系统的正常运行。通过对电力系统变压器故障的早期判断,能够有效地减少由于变压器故障引起的停用,防止电力系统安全事故的发生。因此,了解变压器故障类型与特点,在日常巡检与例行检查中有针对性地对变压器情况进行检查,以免故障进一步扩大,保证电力系统的安全稳定运行。本文主要阐述电力系统变压器的常见故障及产生的原因,常用的诊断方法以及处理方法等问题。     

《基于振动频响法的变压器绕组变形检测》

为了更加有效地识别绕组的变形故障,在基于机械振动频响法对变压器绕组进行检测的基础上,提出了标示绕组形变程度的振动频响曲线相关系数。通过对大型变压器的绕组进行人为故障设定,利用机械振动频响法对故障绕组进行检测,试验证明该振动频响曲线相关系数对判断变压器绕组变形具有较高的灵敏度。     

基于MATLAB/Simulink的牵引变压器建模与仿真

针对多种牵引变压器接线方式,建立数学模型,基于Matlab/Simulink仿真软件,建立牵引变压器的仿真模型,并验证数学模型和仿真模型的一致性。利用所建立仿真模型对不同接线形式牵引变压器在不同条件下对公用电网产生的谐波和负序影响进行仿真试验,对研究各种类型的牵引变压器特性在我国电气化铁路的应用提供条件。     

110kV变压器油色谱异常和故障的分析

110k V的变压器油色谱在发生故障时,综合有变化特性的气体和三比值法等方法。综合考虑把油色谱操作条件、基本结构及异常缺陷情况,进行初步的分析和判断,试验诊断绕组变形与直流电压比,电阻,绝缘电阻值及介质损耗,绕组变形与其他常规测试方法,分析判断故障原因,而后提出相应的改进技术和建议。     

客运专线牵引供电系统电能质量检测装置的研究

一．研究意义 当代电力系统的负荷结构发生了很大的变化,随着电气化铁路建设的飞速发展,电气化铁路牵引供电系统也将在全国快速扩大。截至2007年,国家电网供电范围内已建成的牵引变电站共379座,在建牵引变电站25座。牵引变压器总容量共24807．9MVA,平均每台变压器容量为31．7MVA,单台牵引变压器最大容量达到150MVA。     

Manufacture of elastic composite ring for planetary traction drive with silicon rubber and carbon fiber

Advantages of planetary gear speed reducer are the high degree of efficiency, various reduction ratio, stress distribution by the planet gear and compaction in designing driving system. However there is noise in running at high r.p.m, so the use of planetary gear system is restricted in quiet place such as indoors, etc.

If following problems are solved such as low transmission torque that resulted from the slip and the deformation by the heat generated between ring and planet roller, planet roller and sun roller, the planetary traction drive will have not only the advantage of planetary gear speed reducer, but also silence in running. Thus it can be used at the high r.p.m in noise control area.

In this paper, speed reducer, which uses the elastic displacement of ring as preload, was developed. This system uses composite, which has superior elastic absorption and heat transfer property between ring and housing to exclude the effect of heat from the periodic and continuous elastic deformation of ring. This composite consists of silicon rubber and carbon fiber in a ratio of 7:3.     

机车牵引销冲击动力学特性分析

基于车辆/轨道耦合动力学理论,分析对比了选用两种方案转向架情况下机车动力学特性,以及对牵引销结构冲击的影响。以某型米轨机车为例,结合国外山区线路特征,使用动力学软件SIMPACK构建车轨耦合动力学模型。通过模拟实际线路工况分析发现直线工况下由于牵引销纵向自由间隙的存在,在较差线路上高速运行时,由于轨道纵向激励的影响使得牵引销受到较大的纵向冲击,原始方案三个牵引销按顺序最大纵向力分别为165kN、197kN和167kN;改进后方案的牵引销纵向力最大值为165kN、141kN和186kN。小半径曲线工况下原始方案牵引销与横向止档发生剧烈碰撞,第二位牵引销所受的横向冲击最大,达到259kN,而考虑车轮磨耗时,冲击将达到785kN。改进方案牵引销横向冲击较小,均未超过45kN。结果表明：通过小半径曲线时,牵引销产生的巨大横向力可能是造成牵引销固定螺栓松动、剪断的原因。在较差线路上,轨道不平顺造成的纵向冲击这也可能引起该问题。     

交-直-交型电力机车网侧谐波对牵引变电所的影响及改进

本文分别对比介绍了新型交-直-交型大功率电力机车和以SS4为代表的传统型交-直型电力机车的主电路拓扑结构及其网侧电流谐波特性。由测试结果表明大功率电力机车与传统电力机车相比最显著的特征是其谐波特性不同,并分析了网侧谐波对牵引变电所电气设备造成的影响和采取的相应的技术改进措施,确保牵引供电系统的正常运行。     

AC motor traction drives — A status review

The paper presents a brief review of modernac motor traction drives, powered from 25 kV power frequencyac supply. Drives employing voltage source inverters, current source inverters, and induction and synchronous motors have been discussed.     

Stress field of a disclination dipole in hcp bicrystal with imperfect interface

In this paper, exact stress field solutions are derived for an interfacial disclination dipole in an hcp bicrystal with an imperfect interface described by the traction discontinuity, displacement discontinuity and slipping models. The solutions show that the stress variation is not necessarily monotonic with worsening imperfection and can exceed 100% of the stresses in bicrystals with perfect interfaces. A strong bias exists between the influence of the normal and shear traction jump parameters, and between the influence of the normal and tangential displacement jump parameters, on the interfacial stresses. The traction and displacement discontinuity models also predict very different dependence of the interfacial stresses on the jump parameters. These results suggest that imperfect interfaces may significantly raise the internal stresses and thus drastically alter the damage mechanisms (nucleation and propagation of dislocations/cracks, fatigue, etc.) as well as the mechanical properties (effective properties, failure modes, strength, etc.) of polycrystalline materials.     

一种新型机车动轮弛缓在线监测及报警方案

本文介绍了一种新型机车制动热抱弛缓在线监测方案。该方案以轮箍温度及轮箍和轮辋的相对位移为对象，在线监控机车运行状态，提示司机机车的意外情况，确保机车行车安全。     

Assessment of debond simulation and cohesive zone length in a bonded composite joint

Finite element methods combined with cohesive elements were used to simulate progressive failure behaviour in a bonded double cantilever beam configuration. The introduced cohesive zone was represented by three cases. Responses of both global load–displacement and local cohesive traction–separation were investigated. An unexpected finding was that the overall cohesive traction stiffness was much less than the assumed input value. In addition, the local nodal separation moment was identified. Consequently, correct cohesive zone lengths were obtained using the extracted traction profile along the cohesive zone path at this moment. Information of the global load–displacement profile, traction stiffness, and cohesive zone length induced by the three zone cases was explored. Moreover, the study can explain why very small cohesive zone lengths are generated numerically, as compared to theoretical solutions. Recommendations on the application of the numerical model with cohesive elements to practical experimental analysis were suggested.     

A well-conditioned technique for solving the inverse problem of boundary traction estimation for a constrained vibrating structure

 Estimation of the frequency and spatial dependent boundary traction vector from measured vibration responses in a vibrating structure is addressed. This problem, also referred to as the inverse problem, may in some circumstances be ill-conditioned. Here a technique to overcome the ill-conditioning is proposed. A subset of a set of available eigenmodes is chosen such that the problem becomes well-conditioned enough. It is shown that the ill-conditioning originates from the fact that not all eigenmodes are orthogonal over the surface where the traction vector is sought. Consequently, by choosing a set of eigenmodes orthogonal over the surface of interest, the problem becomes well-conditioned. The calculated traction vector is shown to converge to the true one in the sense of a L₂-norm on the boundary of the body. The proposed technique is verified, using numerical simulation of measured responses, with good agreement. Received: 10 January 2002 / Accepted: 24 October 2002 This work was performed under contract from the Swedish Defence Material Administration (FMV). The funding provided is gratefully acknowledged. The author would like to thank all staff at the Structural Dynamics research group, Department of Structures and Materials, Aeronautics Division, Swedish Defence Research Agency.     

车轮多边形态下机车轮轨动态响应研究

某和谐型电力机车车轮运营中表现出较为严重的多边形磨耗,对机车的零部件失效、乘坐舒适性和运行安全性产生较大影响。为研究车轮多边形态下机车轮轨动态响应规律,基于SIMPACK软件建立了考虑机车牵引行为和轮对、钢轨等部件柔性的刚柔耦合动力学模型,利用机车振动试验结果对模型进行验证。研究了典型车轮多边形阶次、幅值和运行速度等对轮轨力和振动响应的影响,并分析了机车牵引行为对轮轨蠕滑率/力和车轮磨耗的影响。结果表明,速度等级为70 km/h时,车轮18阶多边形态下激发了轮对一阶弯曲共振,出现了轮轨力波动大和机车异常振动的现象;机车牵引状态下显著增大了纵向蠕滑率的波动幅值,并提高了纵向蠕滑力,导致轮轨磨耗指数相比无牵引工况下大幅增加,加剧车轮多边形磨耗的发展。