Time Series as an Aid to Research of Traction Substation Load

In the case of electric or tram traction vehicles, the energy for propulsion purposes, as well as all other purposes, is processed and delivered via traction substations. Knowledge of the course of traction substation loading, especially at the stage of its design, is an extremely important issue because of the choice of the processing equipment of the main circuit or protection devices. In the range of investigations of railway traction substation B in vicinity of Cracow （Poland）, the measurements of current load in hours 4：00 a.m.-8：00 p.m. were realized. The measurements for the analysis were chosen from those realized between 6：00 a.m.-8：00 a.m. （the morning rush time）. Due to the sampling of 2 h summit with a frequency of 2 kHz, the recorded data set contains 1.44 ~ 107 elements. Therefore, the necessary transformation of data was to lower frequency 1 Hz, 10 Hz and 50 Hz. The results of the analysis presented below indicate the effect of such conduct on the obtained results for the parameters of time series models. In view of the unsatisfactory effects of the polynomial approximation, there is a need to seek a more efficient approximation method for achieving the optimum compatibility with the measured process. Continued research should lead to the formulation of procedures, which will determine an acceptable accuracy of the expected variability of traction substation loads.

轨道交通能量互馈式交流牵引传动综合测试系统的设计

针对轨道交通牵引传动系统性能测试与特性试验需求,设计一种列车交流牵引传动测试系统。系统由四象限整流器、DSP控制单元、牵引变流器、负载变流器、牵引电机与负载电机组成。牵引变流系统采用全新的“双变流器--交流电机负载反馈”方案,能量通过直流侧在牵引电机与负载电机之间互馈,避免试验过程中能量的大量消耗。系统可实现牵引变流器的牵引/制动工况性能测试,牵引电机性能测试、特性试验与功率测量,具有高智能化与自动化、安全可靠、测试准确度高、能量利用率高的优点。

考虑电气化铁路接入的山区电网可靠性评估研究

作为大功率、强冲击的移动负荷,电气化铁路接入山区电网后将导致电网线路功率在短时内重新分布,可能引发线路可靠性下降等后果。为此,该文提出一种考虑电气化铁路接入的山区电网可靠性评估方法。首先,考虑途径山区的电气化铁路客货共线的特点,基于列车牵引计算模拟牵引负荷的随机波动性;然后分析牵引负荷对电网潮流的影响;进一步建立线路故障模型对牵引负荷接入后的线路可靠性指标进行计算,量化评估山区电网的可靠性水平;最后,定义线路薄弱度指标对山区电网薄弱环节进行筛选,并提出相应措施以提升电网可靠性。通过算例对比分析优化前后两种情况下的电网可靠性指标,验证了该文所提方法的正确性与有效性。

基于EEMD-CBAM-BiLSTM的牵引负荷超短期预测

针对电气化铁路牵引负荷难以预测的问题,构建了一种由集合经验模态分解(EEMD)、改进型卷积块注意力模块(CBAM)和双向长短期神经网络(BiLSTM)组合成的EEMD-CBAM-BILSTM预测方法,有效地降低了牵引负荷超短期预测误差与计算成本。首先,通过EEMD将牵引负荷数据分解为多个稳定、有规律的时序模态函数,突出负荷数据的时序特征;其次,将分解后的各分量整体通入由卷积神经网络(CNN)和改进型CBAM组成的特征提取模块提取全局时序特征;最后,利用贝叶斯优化(BO)搜寻BiLSTM最优参数,并将全局特征通入优化后的神经网络进行超短期时序预测。仿真算例表明,该文所提预测框架在各预测步长下均能很好地把握牵引负荷变化趋势,显著提升了牵引负荷预测的精度。

考虑铁路牵引负荷接入的电力系统小干扰稳定性分析

随着电气化铁路的飞速发展,电气化铁路牵引负荷已成为中国电力系统中最大的单体负荷,但其负荷特性对电力系统小干扰稳定性的影响尚不明晰。为此,首先建立电气化铁路牵引负荷等效数学模型,并基于此构建考虑牵引负荷接入的电力系统小干扰模型;其次利用特征值分析方法,分析牵引负荷机车速度、机车数量以及牵引负荷接入位置和占比对电力系统小干扰稳定性的影响;最后通过特征值根轨迹寻找同步发电机励磁参数的调节范围,并分析牵引负荷接入前、后和不同牵引负荷参数对电力系统励磁参数调节范围的影响。研究结果表明:牵引负荷接入后电力系统小干扰稳定性降低,系统励磁参数调节范围收缩,系统稳定裕度降低。

振动激励环境下的滚动轴承动载荷测试

载荷是决定轴承使用寿命的关键参数,针对工程应用中轴承实际载荷通常较难获取的问题,基于轴承载荷与接触点位移间的线性关系设计了一种轴承动载荷测试装置。通过静载荷标定得到不同轴承载荷下的力传感器示值,0.99的相关系数表明轴承载荷与力传感器示值呈高度线性相关,采用一元线性回归方法进行拟合,得到轴承载荷与力传感器示值的转化系数,进而通过轴承动载荷测试装置有效测试了振动激励环境下的轴承动载荷。

2万吨重载列车牵引启动工况的纵向冲动分析

车钩是重载列车的传递纵向冲击的关键部件,车钩力大小对重载列车的运行安全具有重大影响.为分析2万吨重载列车在不同牵引工况启动时的车钩力的大小,基于列车纵向动力学理论、列车操纵方法以及钩缓装置动力学建模方法的基础上,建立了HXD1型机车和C80型运煤敞车编组的2万吨重载列车纵向动力学模型,分析了重载列车在不同牵引力、从控机车滞后及其不同车钩间隙时牵引启动的车钩力分布规律.通过分析可以得出:牵引力提升速度对稳态车钩力大小影响不明显,而牵引档位的增加,稳态最大车钩力明显增加,在保障列车能正常牵引启动的同时应减小牵引档位;随着主控机车与从控机车启动相差时间的增加,编组车辆中部及尾部的拉钩力增加,应尽可能地保障列车同步操纵;重载列车车钩间隙对启动时车钩拉力影响明显,应重视加强对车钩间隙的检修,同时配合牵引杆的使用可以降低车钩力.

基于运行图优化的重载牵引负荷削峰策略研究

重载铁路牵引负荷具有功率大、随机波动性强的特点,既有牵引负荷削峰方法需要储能装置,成本投入大。基于运行图的合理优化进行牵引负荷削峰,可提高现有行车密度,且具有较好的经济效益。本文通过分析列车追踪间隔对牵引变电所功率的影响,建立基于运行图优化的牵引负荷削峰模型,基于遗传算法求解列车最小追踪间隔,并以实际案例分析了模型效果。

城市轨道交通灵活编组优势及实现条件分析

城市轨道交通列车编组方案影响因素众多,需综合研究确定。灵活编组能够实现客流需求与运输能力的精准匹配,提高满载率,降低牵引能耗和运营成本,对轨道交通绿色可持续发展具有重大意义。以某线路为例,对灵活编组的优势做定性和定量分析,并对“3+3”灵活编组方案的实现条件进行详细研究,结果表明:采用灵活编组方案,满载率能够提高约24.3%;牵引能耗降低约32.6%,全年可节省运营成本约1073万元,具有较好的经济效益;灵活编组对车站土建规模、场段规模均无影响;在站后折返线、停车线等区域进行解编联挂时,对配线长度基本无影响;为实现列车在线解编联挂,设备系统需增加相应的功能。

静止无功发生器在电气化铁路中的应用与探索

针对电气化铁路单相、非线性的冲击负荷的特点,静止无功发生器(SVG)对于提高牵引供电系统功率因数具有重要意义。该文主要介绍SVG的工作原理,并以黔桂线南丹牵引变电所SVG改造工程为背景,以减少运行单位罚款为契机,通过改变SVG装置电流采样点位置来补偿全所无功功率的可行性进行理论分析及实践。结果表明,通过此种方式,尤其在轻负荷侧安装时,容易造成过补偿,引起补偿支路过电压跳闸。为同类工程在实施提供借鉴,具有一定参考意义。

高速列车牵引电动机脂润滑轴承的温升及其影响因素

随着轨道交通车辆朝着高速、大功率方向发展,牵引电动机轴承尺寸与速度同步增大,目前高速列车脂润滑轴承dmn值最大可达70×10^(4) mm∙r/min,远高于早期直流传动机车脂润滑轴承dmn值(32×10^(4) mm∙r/min),给轴承温度及使用寿命带来了严峻挑战。针对高dmn值轴承发热量大的问题,根据脂润滑轴承的温升行为建立了脂润滑轴承温升计算模型和试验装置,仿真和试验验证了轴承载荷、润滑脂黏度、dmn值对轴承温升的影响规律,结果表明dmn值对轴承温升的影响最大。

高寒动车组牵引变流器的振动测试及分析

针对我国西北部地区恶劣天气和老化线路影响高寒动车组安全可靠运行的问题,开展实际线路运行时振动测试及分析。根据即墨至乌鲁木齐的车辆运行速度和地形特征,划分青岛—济南、济南—西安、西安—兰州、兰州—乌鲁木齐4个区间,对比分析不同区间内的振动有效值。结合IEC 61373标准,对比分析实测振动有效值、冲击峰值与标准值的差异。通过振动频谱分析牵引变流器不同部件的振动特性,利用统计容差法编制不同部件的实测载荷谱,并利用有限元方法分析中频和高频振动对牵引变流器结构的影响。结果表明,济南—西安区间内的振动高于其他区间,西安—兰州区间内的冲击高于其他区间;柜体吊耳和控制箱的振动主要体现在垂向与纵向,而横向较小,且以中频段和低频段为主;冷却风机的振动集中在低频段,来自于风机转频;功率模块振动以横向和纵向为主,中频段和高频段的振动远大于低频段。

矿山有轨运输电机车双机牵引技术及无人化应用研究

本文对现有矿山有轨运输电机车双机牵引技术应用进行了调查及研究,对矿山有轨运输环节双机牵引运输方式从其应用背景、工艺特点、关键技术及目前的应用情况进行了分析讨论。主要总结了双机牵引的通讯技术、联动控制技术和负载平衡技术的应用;从控制连续性、制动距离、调度效率和运输适应性等方面探讨总结了双机牵引运输方式的优缺点和应用前景,为矿山有轨运输系统的无人化、智能化设计及改造实施提供了一定的参考依据。

曳引电梯轿厢垂直振动特性研究

对电梯垂直方向的振动研究是提高电梯运行性能的关键,基于曳引比为2∶1的电梯系统,建立垂直方向上的动力学模型,分析轿厢载重和提升高度等参数对轿厢振动的影响及参数变化时系统的谐响应和惯性力响应,并对电梯制动的动载系数变化进行研究。结果表明,曳引机也是电梯轿厢振动的重要振源,轿厢振动与载荷质量和提升高度呈正比。

融通型牵引供电系统变压器负荷电流特性研究

铁路功率调节器RPC是一种电能质量补偿设备,采用该装置的融通型牵引供电系统供电结构能够实现能量互联,并为低碳供能提供新的可能性。为提高融通型牵引供电系统中牵引变压器供电的安全性和可靠性,提出一种综合考虑RPC不同容量的变压器最大负荷计算方法。基于系统拓扑结构分析RPC接入后牵引变压器负荷电流特性,得出精确计算最大负荷电流的必要性,并结合RPC不同容量下的补偿度推导变压器低压侧最大负荷电流的计算式,最后仿真验证计算式的正确性。

开行3万吨重载列车运输组织方案研究

紧跟世界重载铁路先进技术水平,提高运输能力,我国有必要发展3万吨重载列车。以大秦线为例,借鉴2万吨重载列车开行经验,探讨开行3万吨重载列车的运输组织方案,采用组合站始发—直达终到站分解卸车—空车返回的循环运输模式,从列车始发作业站、编组方式、列车检查、司机换班、终到分解、回空运行等方面,阐述运输组织方案的合理性。考虑运输能力受始发作业站能力、牵引供电能力、区间通过能力的限制,检算始发组合站到发线能力及重车方向运输能力,结果表明,在现有列车开行方案基础上,开行6列3万吨重载列车,平均通过能力利用率达到93.1%,输送能力可提升0.49亿t,运输能力提高11.5%,扩能效果良好;也可以选择采用3万吨重载列车1∶1替换2万吨重载列车的组织方式,输送能力可提升0.17亿t。

Analytical solutions of uniform extended dislocations and tractions over a circular area in anisotropic magnetoelectroelastic bimaterials

In this paper, we derive the analytical solutions in a three-dimensional anisotropic magnetoelectroelastic bimaterial space subject to uniform extended dislocations and tractions within a horizontal circular area. By virtue of the Stroh formalism and Fourier transformation, the final expression of solutions in the physical domain contains only line integrals over [0, 2π] rather than infinite integrals. As the reduced cases, the half-space and homogeneous full-space solutions can be directly derived from the present solutions. Also, in terms of material domains, the present solutions can be reduced to the piezoelectric, piezomagnetic, purely elastic materials with different symmetries of material prop- erty. To carry out numerical calculations, Gauss quadrature is adopted. In the numerical examples, the effect of different loading locations on the response at the interface is analyzed. It is shown that, when the magnetic traction or electric dislocation is applied, the physical quantities on the interface may not decrease monotonically as the loading area moves away from the interface. The distributions of different in-plane physical quantities on the upper and lower interfaces under various extended horizontal loadings are compared and the differences are discussed. The work presented in this paper can serve as benchmarks for future numerical studies in related research fields.

Crack Propagation Path in Two-Directionally Graded Composites Subjected to Mixed-Mode Ⅰ+Ⅱ Loading

Crack propagation path in two-directionally graded composites was investigated by the finite element method.A graded extended finite element method(XFEM)was employed to calculate displacement and stress fields in cracked graded structures.And a post-processing subroutine of interaction energy integral was implemented to extract the mixed-mode stress intensity factors(SIFs).The maximum hoop stress(MHS)criterion was adopted to predict crack growth direction based on the assumption of local homogenization of asymptotic crack-tip fields in graded materials.Effects of material nonhomogeneous parameters on crack propagation paths were also discussed in detail.It is shown that the present method can provide relatively accurate predictions of crack paths in two-directionally graded composites.Crack propagates in the decreasing direction of effective Young′s modulus.The shape and steepness of property gradient perpendicular to the crack surface have great influences on crack paths.Through redesigning material property reasonably,crack growth in graded material can be changed to improve mechanical behaviours of cracked structures.

Investigation of Power Factor Behavior in AC Railway System Based on Special Traction Transformers

The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unbalance loading are investigated simultaneously for electrical railway systems. Special traction transformers (i.e. single-phase, V/V, Wye-Delta, Scott, and Le Blanc) are used between the utility grid and the traction load. For analysis, different defini-tions of power factors are considered, which are presented by IEEE Std.1459. The detailed simulation study is made with MATLAB/SIMULINK program to represent the impacts of harmonic components and unbalance loading on the power factor behavior in the Electrical Railway systems.

Study on Electromagnetic Transient Condition of EMU Passing by Phase-separation with Electric Load in High-speed Railway

Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.