Pantograph-catenary electrical contact system of high-speed railways:recent progress,challenges,and outlooks

As the unique power entrance,the pantograph-catenary electrical contact system maintains the efficiency and reliability of power transmission for the high-speed train.Along with the fast development of high-speed railways all over the world,some commercialized lines are built for covering the remote places under harsh environment,especially in China;these environmental elements including wind,sand,rain,thunder,ice and snow need to be considered during the design of the pantograph-catenary system.The pantograph-catenary system includes the pantograph,the contact wire and the interface—pantograph slide.As the key component,this pantograph slide plays a critical role in reliable power transmission under dynamic condition.The fundamental material characteristics of the pantograph slide and contact wire such as electrical conductivity,impact resistance,wear resistance,etc.,directly determine the sliding electrical contact performance of the pantograph-catenary system;meanwhile,different detection methods of the pantograph-catenary system are crucial for the reliability of service and maintenance.In addition,the challenges brought from extreme operational conditions are discussed,taking the Sichuan-Tibet Railway currently under construction as a special example with the high-altitude climate.The outlook for developing the ultra-high-speed train equipped with the novel pantograph-catenary system which can address the harsher operational environment is also involved.This paper has provided a comprehensive review of the high-speed railway pantograph-catenary systems,including its progress,challenges,outlooks in the history and future.

Air flow patterns and noise analysis inside high speed angular contact ball bearings

The vortex formed around the rolling ball and the high pressure region formed around the ball-raceway contact zone are the principle factors that barricades the lubricant entering the bearing cavity, and further causes improper lubrication. The investigation of the air phase flow inside the bearing cavity is essential for the optimization of the oil-air two-phase lubrication method. With the revolutionary reference frame describing the bearing motion, a highly precise air phase flow model inside the angular contact ball bearing cavity was build up. Comprehensive factors such as bearing revolution, ball rotation, and cage structure were considered to investigate the influences on the air phase flow and heat transfer efficiency. The aerodynamic noise was also analyzed. The result shows that the ball spinning leads to the pressure rise and uneven pressure distribution. The air phase velocity, pressure and cage heat transfer efficiency increase as the revolving speed increases. The operating noise is largely due to the impact of the high speed external flow on the bearing. When the center of the oil-air outlet fixes near the inner ring, the aerodynamic noise is reduced. The position near the inner ring on the bigger axial side is the ideal position to fix the lubricating device for the angular contact ball bearing.

An analysis method for correlation between catenary irregularities and pantograph-catenary contact force

Pantograph-catenary contact force provides the main basis for evaluation of current quality collection; however,the pantograph-catenary contact force is largely affected by the catenary irregularities.To analyze the correlated relationship between catenary irregularities and pantograph-catenary contact force,a method based on nonlinear auto-regressive with exogenous input(NARX) neural networks was developed.First,to collect the test data of catenary irregularities and contact force,the pantograph/catenary dynamics model was established and dynamic simulation was conducted using MATLAB/Simulink.Second,catenary irregularities were used as the input to NARX neural network and the contact force was determined as output of the NARX neural network,in which the neural network was trained by an improved training mechanism based on the regularization algorithm.The simulation results show that the testing error and correlation coefficient are 0.1100 and 0.8029,respectively,and the prediction accuracy is satisfactory.And the comparisons with other algorithms indicate the validity and superiority of the proposed approach.

Multi-point Contact of the High-speed Vehicle-turnout System Dynamics

The wheel-rail contact problems, such as the number, location and the track of contact patches, are very important for optimizing the spatial structure of the rails and lowering the vehicle-turnout system dynamics. However, the above problems are not well solved currently because of having the difficulties in how to determine the multi-contact, to preciously present the changeable profiles of the rails and to establish an accurate spatial turnout system dynamics model. Based on a high-speed vehicle-turnout coupled model in which the track is modeled as flexible with rails and sleepers represented by beams, the line tracing extreme point method is introduced to investigate the wheel-rail multiple contact conditions and the key sections of the blade rail, longer nose rail, shorter rail in the switch and nose rail area are discretized to represent the varying profiles of rails in the turnout. The dynamic interaction between the vehicle and turnout is simulated for cases of the vehicle divergently passing the turnout and the multi-point contact is obtained. The tracks of the contact patches on the top of the rails are presented and the wheel-rail impact forces are offered in comparison with the contact patches transference on the rails. The numerical simulation results indicate that the length of two-point contact occurrence of a worn wheel profile and rails is longer than that of the new wheel profile and rails; The two-point contact definitely occurs in the switch and crossing area. Generally, three-point contact doesn’t occur for the new rail profile, which is testified by the wheel-rails interpolation distance and the first order derivative function of the tracing line extreme points. The presented research is not only helpful to optimize the structure of the turnout, but also useful to lower the dynamics of the high speed vehicle-turnout system.

Pantograph-catenary are test apparatus for high-speed railway

With the continuous increase of train speed,undulations of catenary and vibrations of the pantograph head result in generating pantograph- catenary arc frequently,intensifying the abrasion between pantograph strip and catenary wire,which has seriously influenced the current collection and safety of electric multi units(EMU). It is necessary to study the pantographcatenary arc in immediately. Some researchers develop a few pantograph- catenary arc testing equipment,which couldn’t really reflect the operating condition of pantograph-catenary system. In this paper,the pantograph-catenary arc test apparatus was developed,which simulated the flexible and straight contact of pantograph strip and catenary wire,based on the coupling relationship between pantograph and catenary. The equipment was used to research the electrical parameters of the pantograph-catenary arc and the dynamic contact resistance.

CORRELATION INVESTIGATION BETWEEN CONTACT APPROACH SPEED OF HANDHELD METAL ROD AND DISCHARGE PARAMETERS FROM CHARGED HUMAN BODY

Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science (SPSS), for various charge voltages, which is based on the effect test of electrode contact approach speeds on discharge current parameters of current peaks, maximum rising slope and spark lengths. Discharge parameters at charge voltage 300V are independent on approach speed. For charge voltages equal to and higher than 500V, the contact approach speed has strong positive cor- relation with discharge parameters of the peak current and the maximum rising slope, whereas has strong negative correlation with the spark length.

Analysis of Dual-Core Type City and Its Hinterland Contact Pattern under the Background of High-Speed Rail Networking—Urban Agglomeration in Zhejiang Province as an Example

Under the background of high-speed rail networking, this paper uses the passenger trains, the type and direction of the railway via Hang Yong and its extension road line, to construct adsorption and dependency index among cities, depict the contact pattern between the Hang Yong dual-core and its hinterland, measure the “net effect” that two center cities (Hangzhou, Ningbo) have on their hinterland, and estimate population agglomeration potential and future possible population flows of Zhejiang Province and the main sample cities. The result shows that, compared with Ningbo, Hangzhou has stronger radiation force to the vast majority of sample cities, and the sample cities affected more by Ningbo mainly concentrates in Ningbo-Taizhou-Wenzhou along;in addition, the sample cities such as Hangzhou, Ningbo and so on show better population agglomeration, then the population “scramble” phenomenon between cities has begun to appear.

高速电磁能推进装置枢轨接触特性分析及实验研究

为准确分析高速增强型电磁能推进装置枢轨接触特性,提出了一种数值计算与实验测量相结合的方法,对推进装置枢轨接触特性进行动态分析。首先,建立接触电阻与膛口电压、轨道电流、磁场等物理量之间的数学模型,并设计实验对膛口电压、轨道电流、电枢速度以及空间磁场等装置参数进行测量;其次,通过膛口电压与轨道电流等实验测量数据和有限元数值计算结果,对增强型电磁能推进装置枢轨接触电阻进行计算;进一步根据接触电阻计算结果与电枢速度特性曲线,对不同阶段下推进装置枢轨接触特性进行分析;最后,将服役后的导轨进行拆解和形貌扫描,通过样貌图侧面验证了不同阶段接触特性分析的可靠性。研究结果表明:初始阶段枢轨接触电阻最大可达8.5 mΩ,且轨道在此阶段损伤较为严重;在加速至中高速阶段,接触电阻基本平稳在0.78 mΩ左右,枢轨接触状态较为稳定;在高速运动至出口阶段,接触电阻波动幅度较大,电接触稳定性差。研究内容可为轨道磨损以及提高系统性能等提供基础数据和新的可靠参考。

Effects of Service Condition on Rolling Contact Fatigue Failure Mechanism and Lifetime of Thermal Spray Coatings——A Review

The service condition determines the Roiling Contact Fatigue（RCF） failure mechanism and lifetime under ascertain material structure integrity parameter of thermal spray coating. The available literature on the RCF testing of thermal spray coatings under various condition services is considerable; it is generally difficult to synthesize all of the result to obtain a comprehensive understanding of the parameters which has a great effect on a thermal spray coating＇s resistance of RCF. The effects of service conditions（lubrication states, contact stresses, revolve speed, and slip ratio） on the changing of thermal spray coatings＇ contact fatigue lifetime is introduced systematically. The effects of different service condition on RCF failure mechanism of thermal spray coating from the change of material structure integrity are also summarized. Moreover, In order to enhance the RCF performance, the parameter optimal design formula of service condition and material structure integrity is proposed based on the effect of service condition on thermal spray coatings＇ contact fatigue lifetime and RCF failure mechanism. The shortage of available literature and the forecast focus in future researches are discussed based on available research. The explicit result of RCF lifetime law and parameter optimal design formula in term of lubrication states, contact stresses, revolve speed, and slip ratio, is significant to improve the RCF performance on the engineering application.

Evolution of the electrical contact of dynamic pantograph–catenary system

A good contact between the pantograph and catenary is critically important for the working reliability of electric trains, while the basic understanding on the electrical contact evolution during the pantograph--catenary system working is still ambiguous so far. In this paper, the evolution of electric contact was studied in respects of the contact resistance, temperature rise, and microstructure variation, based on a home-made pantograph-catenary simulation system. Pure carbon strips and copper alloy contact wires were used, and the experimental electrical current, sliding speed, and normal force were set as 80 A, 30 km/h, and 80 N, respectively. The contact resistance presented a fluctuation without obvious regularity, concentrating in the region of 25 and 50 mf~. Temperature rise of the contact point experienced a fast increase at the first several minutes and finally reached a steady state. The surface damage of carbon trips in microstructure analysis revealed a complicated interaction of the sliding friction, joule heating, and arc erosion.

Effect of photovoltaic panel electric field on the wind speed required for dust removal from the panels

Methods to remove dust deposits by high-speed airflow have significant potential applications,with optimal design of flow velocity being the core technology.In this paper,we discuss the wind speed required for particle removal from photovoltaic(PV)panels by compressed air by analyzing the force exerted on the dust deposited on inclined photovoltaic panels,which also included different electrification mechanisms of dust while it is in contact with the PV panel.The results show that the effect of the particle charging mechanism in the electric field generated by the PV panel is greatly smaller than the effect of the Van der Waals force and gravity,but the effect of the particle charged by the contact electrification mechanism in the electrostatic field is very pronounced.The wind speed required for dust removal from the PV panel increases linearly with the PV panel electric field,so we suggest that the nighttime,when the PV electric field is relatively small,would be more appropriate time for dust removal.The above results are of great scientific importance for accurately grasping the dust distribution law and for achieving scientific removal of dust on PV panels.

Effect of wheelset flexibility on wheel–rail contact behavior and a specific coupling of wheel–rail contact to flexible wheelset

The fexibility of a train＇s wheelset can have a large effect on vehicle–track dynamic responses in the medium to high frequency range.To investigate the effects of wheelset bending and axial deformation of the wheel web,a specifi coupling of wheel–rail contact with a fexible wheelset is presented and integrated into a conventional vehicle–track dynamic system model.Both conventional and the proposed dynamic system models are used to carry out numerical analyses on the effects of wheelset bending and axial deformation of the wheel web on wheel–rail rolling contact behaviors.Excitations with various irregularities and speeds were considered.The irregularities included measured track irregularity and harmonic irregularities with two different wavelengths.The speeds ranged from 200 to400km/h.The results show that the proposed model can characterize the effects of fexible wheelset deformation on the wheel–rail rolling contact behavior very well.

Simulation on derailment base on a new wheel-rail contact method

The simulation package for special research on derailment of high speed vehicle is established.The process of derailment is different from other behaviors of vehicle dynamics because of large lateral displacement of wheelsets.To get correct results,a new fast algorithm to computing contact force is adopted and the exact geometry analysis is necessary to judge derailment happened.Variation of contact condition and coefficient of friction with speeds are also considered into vehicle-track coupled model.The structure of the package is presented in detail.The results are particular emphasis on investigation influence of maximum track defect,critical vehicle speed and various contact condition on derailment.The simulation can also be used to define the most risk factor leading to derailment.

SOLVING CONTACT PROBLEM WITH FRICTION BY A NEW FAST BOUNDARY ELEMENT METHOD

The formulation of boundary element method for handling contact problems with friction and the technique for high speed contact analysis are presented. This formulation is based on the idea of modifying the length of contact elements without altering the total number of elements. The high precision of solution and high speed analysis are verified according to the results of conventional method and analysis method.

更高速下轮轨瞬态“滚-滑-跳”接触行为及中/短波不平顺临界限值研究

简述轮轨滚动接触行为预测方法现状的基础上,选择最适于400 km/h及以上更高速和中/短波不平顺激励下轮轨“滚-滑-跳”接触行为分析的瞬态滚动接触显式有限元建模方法,建立更高速轮轨三维瞬态滚动接触时域分析模型,数值模拟了轮对在典型曲线轨道上的瞬态曲线通过行为。根据现营高速轮轨的中/短波不平顺调研,以波长30~210 mm钢轨波磨为典型不平顺,考虑波磨激励下左右两侧轮轨动力作用相互影响,分析波磨几何等因素对速度500 km/h及以下轮轨瞬态“滚-滑-跳”接触行为的影响。考虑低、中频动力减载等因素的前提下,仅从轮轨接触脱离角度,提出轮轨中/短波不平顺的临界管理限值建议,讨论其重要性、合理性和应用局限,并与《高速铁路钢轨打磨管理办法》规定的波磨整治限度进行对比。

锥面分段开孔高速刀柄的设计方法

根据高速刀柄在不同过盈量下的联接性能分析结果与不同转速下的锥面接触应力分布规律,提出了一种锥面分段开孔高速刀柄的设计方法,即对刀柄定位锥面按照锥体素线长度均等分成前、中、后三段,并在各段的中等分处周向均布一组盲孔,通过调控盲孔的数量与尺寸使刀柄锥面达到一定的柔度。文章阐述了盲孔开设参数对锥面接触应力、柔度的影响规律和参数确定原则,给出了以HSK-E50为原型的锥面分段开孔设计案例,采用有限元分析其极限转速和锥面接触应力分布情况。结果表明,锥面分段开孔刀柄与原型刀柄相比,极限转速提高了约10.79%,锥面接触应力分布显著均匀。

高速铁路大跨度钢桁架桥接触网腕臂安装技术研究

高速铁路大跨度钢桁架桥纵向伸缩量大且变位复杂,是影响接触网腕臂偏移等系统能否正常、安全运行的重要因素,如何解决接触网腕臂安装、偏移调整与钢梁伸缩之间的协同配合,目前国内在此方面鲜有研究。通过阐述受导线伸缩影响的腕臂偏移机理和大跨度钢桁架桥梁体纵向伸缩机理,分析在不同接触网锚段布置方式下大跨度钢桁架桥梁体伸缩对腕臂偏移的影响,并采用逐工点分析法总结不同工况下钢梁伸缩与导线伸缩对腕臂偏移影响的相互关系,揭示了接触网腕臂安装曲线在导线伸缩及钢梁伸缩共同作用下的计算方法。结合典型案例计算分析,建议采用不同钢梁跨度下的推荐锚段布置方式能有效降低腕臂偏移量,并提出应重点关注伸缩缝两侧锚段腕臂偏移问题、腕臂偏移为叠加关系时缩小半锚长度、钢梁跨度大于720 m时应重点计算伸缩缝两侧双腕臂间距等优化事项。研究内容及计算公式可为系统性解决高速铁路大跨度钢桁架桥接触网腕臂偏移设计、施工及运营维护等技术难题提供理论支持。

汽车衡全自动无接触计量的应用

鞍钢股份有限公司鲅鱼圈钢铁分公司汽车衡计量发展经历了手动计量、联网计量、自助计量到现在的全自动计量的发展过程,目前采用的全自动汽车衡的计量方式将整个称重流程进行了优化,称重速度显著提高,适应了日益增长的汽车衡称重需求。

基于空间域尺度自适应小波能量的接触网不规则识别

针对高速铁路受电弓−接触网系统中出现的接触网垂向和横向结构不规则问题,在研究接触网不规则对受电弓振动响应影响的基础上,提出一种基于弓头加速度的空间域尺度自适应小波能量识别接触网结构不规则的方法,并开展仿真和现场实测验证。首先,建立受电弓刚柔耦合动力学模型,对不同接触位置下的弓头振动响应进行分析,并建立弓网刚柔耦合动力学模型获取弓头加速度信号,根据标准和实验结果验证模型的准确性;其次,利用连续小波变换对信号时频分析并进行空间域转换,基于空间域中的能量分布特征自适应提取表征接触网不规则的尺度参数;最后,提取尺度参数下的平均小波能量作为特征分量进行融合,实现接触网不规则识别。研究结果表明:本文所提方法能够有效地从弓头振动信号中同时检测出接触网垂向幅值大于0.5 mm的不平顺以及横向定位器偏离故障。

直流开断中触头边缘弧根停滞现象及影响因素研究

弧根演化过程对直流空气断路器的开关效率有显著影响。基于空气电弧磁流体动力学(MHD)模型,对触头边缘弧根停滞的根本原因进行仿真分析,得出外磁场大小和开断速度对触头边缘弧根停滞的影响。结果表明,弧根从触头转移至跑弧道是通过击穿完成的,触头边缘弧根停滞是弧根转移前跑弧道未达到击穿条件导致的。触头边缘弧根停滞时间随磁感应强度的增大而减少,并减少速度变慢,最后趋于稳定;燃弧初期,一定范围内提高触头开断速度有利于减少弧根停滞时间,但受洛伦兹力和气流场的双重影响,过高的开断速度对减少电弧停滞时间的效果减弱。