电力机车变压器和应涌流产生机理与影响因素

为研究电气化铁道电力机车变压器和应涌流产生机理,建立了牵引供电系统、合闸电力机车以及运行电力机车的数学模型,利用Laplace变换求解出机车变压器磁链的解析解。通过搭建车网仿真平台分析了合闸变压器和运行变压器的磁链变化过程以及多种条件下和应涌流的变化规律,得到了影响和应涌流变化的关键因素,并分析了励磁涌流以及和应涌流对牵引网电压的影响。分析结果表明了合闸电力机车的励磁涌流会造成运行电力机车出现和应涌流现象,并造成牵引网电压发生严重跌落和畸变,为车网系统出现的异常跳闸现象提供参考。     

机车牵引电机定子绕组集肤效应分析

以大功率交流传动HXD1B型电力机车牵引电机为例,根据电磁场理论,建立电机二维电磁场数学模型,并确定其求解域。利用有限元法,对电机恒功率工况下的负载场和参数进行计算和分析,比较了定子上、下层绕组电流相位角相差0°和180°两种情况下的电磁场。对同一个槽内不同绕组的电流分布进行了对比,确定了额定工况下导体沿径向不同位置的电阻增加系数,并得出一些有益的结论。     

Electromagnetic compatibility of a traction power-supply system and infrastructure elements in areas with high traffic

Electric traction systems are improved as part of the process of updating the entire system that converts the power that is consumed by the transportation process. Application of dc converters to a three-phase alternating current, the use of thyristor converters of the dc voltage level, the creation of highly efficient algorithms for computer control of electric-power conversion, and substitution of commutator dc motors for brushless three-phase ac motors lie at the core of technological improvement of electric traction systems and are now widely used in a number of industrialized countries. This paper proposes new traction power-supply systems for areas with high traffic, which require additional wires to be laid and multiconductor lines to be used. The requirements are formulated, and a methodology for grounding the electromagnetic compatibility of multiconductor lines of traction power supply and infrastructure elements is discussed. It is shown that electromagnetic coupling of lines takes place under conditions of both electric and magnetic effects between two or more electrically long lines. In electrically long lines, the voltages and currents cannot be considered independent of each other. They are interconnected through the impedance of the respective line (similarly to how electrical and magnetic fields of electromagnetic waves are linked with each other through the impedance of space). The studies and analysis that were carried out showed t6hat it is possible to simulate the propagation of electromagnetic waves along multiconductor traction power-supply lines, which allow determining not only the currents and voltages at any given point of a multiconductor line, but also simultaneously induced voltages at an adjacent line. All this allows highly accurate checking of the electromagnetic compatibility of the traction network and longitudinal power supply lines with communication lines and track circuits in areas with high traffic.     

频域法在牵引网故障测距中的应用

针对牵引网目前广泛应用的故障测距算法易受整次、非整次谐波、机车负荷以及线路参数波动的影响,提出一种利用线路单端暂态电压进行精确故障测距的新算法。通过理论分析得到测量段等效阻抗的谐振频率与故障暂态电压、电流频谱极大值频率相对应的结论。进一步根据测量端等效阻抗的谐振频率与故障距离相对应的关系建立测距公式,采用频域法分析故障暂态信号在高频段的频率特性,实现精确测距。通过EMTDC仿真验证,该算法基本不受过渡电阻、机车及线路参数小范围波动等因素的影响,测距结果准确且鲁棒性强,具有较高的工程应用价值。     

Simulation Model of a Direct-Current Electric Locomotive with Commutator Traction Motors

A dc electric locomotive simulation model is considered that makes it possible to study transient and steady processes and may serve as a basis for the notion of a “digital locomotive” being implemented within the “Digital Railway” project. One of the most popular electric locomotives is selected, which is designed for pulling freight trains along long-distance railways electrified with direct current with a voltage of 3000 V. The electric locomotive model is based on a mathematical model of a collector traction engine. The model takes into account the nonlinearity of the main pole’s magnetic characteristic, as well as the effect of eddy currents in solid magnetic circuit sections on the magnetic flux variation. The model provides a mechanism for regulating motors in the course of investigations in accordance with operating conditions. The processes of resistor starting and voltage regulation by connection to resistors by means of transposition, as well as motor regulation by changing the magnetic flux, are taken into account. The possibility of using the developed model to study the traction substation–traction network–electric rolling stock system, which is determined by different operating modes of the traction network in the process of converting electrical energy into mechanical, is shown. Calculations of various locomotive operating modes in the event of failure in the contact network are carried out.     

计及弓网二次燃弧的高铁车网建模与电磁暂态影响研究

针对高铁弓网燃弧造成的电磁暂态现象,基于多导体传输线(MTL)理论对计及弓网二次燃弧的牵引网回路进行车-网建模仿真研究。推导高铁全并联自耦变压器(AT)供电方式下牵引网MTL链式集总π型网络矩阵参数;根据CRH2型动车组结构参数,结合动车组实际运行过程中车体、钢轨、牵引网三者之间的相对位置分布及电气参数关系,在MATLAB/Simulink上建立精确的高速铁路车-网链式参数仿真模型。以二次燃弧为主,仿真分析燃弧对牵引网电压、动车组车体电势、轮对泄流、轮对间轨电位差的影响,结果表明:所建模型可有效模拟高速铁路中稳定的工频工况及弓网离线期间一次燃弧和多次燃弧的电磁暂态现象。     

Y/>/平衡变压器运行特性分析与模型试验

该文分析了Y/>/平衡变压器的接线原理,论证了该变压器在不同运行工况时两侧电流的映射关系,在此基础上对该变压器的模型进行了全面的试验验证。试验结果表明:该变压器的理论分析正确,模型的参数和结构设计合理,工艺易于实现;当负荷大范围变化时,原方三相系统的对称性好,副方任一相的输出电压几乎不受另一相负荷变化的影响,抑制负序分量的能力强。应用于电气化铁道做牵引供电变压器时,不仅能较好抑制负序电流对电力系统的影响,而且能提高牵引网的电压水平,有利于电力机车的安全稳定运行。     

The process of traction-current asymmetry generation in rail lines

The main sources of interference in automated devices and telemechanical devices at electrified railways are electric traction currents and harmonics thereof. On railways in Russia, such interference causes an average of 30 automatic locomotive signaling (ALS) failures every hour. The electrical and electromagnetic processes as a result of which such interference occurs are not understood. It remained unclear why the traction-current asymmetry in the rail line is a function of this current and is always greater than the asymmetry of resistances of these track rails. This paper presents some results of clarifying the causal factors involved. It is found that the primary cause of traction-current asymmetry in the rail lines is the emergence of asymmetry of resistances in the track rails. However, the asymmetry of the traction current is largely due to the emerging asymmetry of effective resistivities of mutual inductance of the track rails. It is also explained why the increase of traction current in the rails when heavy trains are in operation and in areas of traction substations does not lead to a proportional increase in the number of failures in the operation of rail electric circuits and automatic locomotive signaling.     

基于有源滤波器自适应阻抗重塑的高速铁路谐波谐振抑制

针对电力机车和牵引网阻抗参数耦合所引起的牵引供电系统的谐波谐振现象,首先基于阻抗分析法建立了有源滤波器、电力机车和牵引网的小信号阻抗模型,使用广义奈奎斯特判据分析了牵引供电系统谐波谐振的机理以及有源滤波器对牵引供电系统谐波谐振的影响。其次,提出一种基于阻抗重塑的牵引供电系统谐波谐振抑制方法,通过并网点电压前馈的方式在有源滤波器中引入虚拟阻抗,并利用自适应参数设计提升了虚拟阻抗对动态系统的适应性。最后,在Matlab/Simulink中搭建了“牵引网-电力机车-有源滤波器”统一仿真模型,验证有源滤波器的自适应阻抗重塑对谐波谐振抑制的有效性。     

车网耦合作用下励磁涌流对机车变流器电流频谱的影响

电力机车或动车组的车载牵引变压器在过分相合闸和弓网离线后恢复供电均会产生励磁涌流,但对于励磁涌流作用下的变流器运行特性研究不够深入。首先,从时域上分析了励磁涌流的产生机理,指出涌流会使车载变压器一、二次侧电压发生跌落,恶化变流器的输入侧电能质量;从频域上推导了涌流的频谱表达式,指出涌流含有较大的低次谐波和丰富的高次谐波。其次,给出了励磁涌流与牵引网阻抗耦合引起牵引网谐振现象的机理,结合机车的瞬态电流控制策略,给出了包含涌流、牵引网、机车控制策略在内的车网耦合数学表达式。理论分析表明:励磁涌流的激励使牵引网电压畸变,在畸变的牵引网电压作用下,变流器输出电流的主要频谱分布含有与牵引网谐振点一致的非特征次频谱,该非特征次频谱分量能够维持牵引网持续谐振。最后,基于MATLAB/Simulink搭建了系统的仿真模型,验证了理论分析的正确性。     

基于阻抗分压原理的牵引网谐波谐振研究

为了研究牵引网谐波谐振特性,建立了基于戴维南谐波电压源模型的牵引供电系统车网互联谐波电路模型,采用阻抗分压原理分析了牵引网谐振过电压的产生机理。利用Matlab/Simulink仿真软件研究了牵引网谐波谐振特性及谐振过电压现象。仿真结果表明:当机车变流器交流侧电压谐波含量较大的频率与牵引网谐振点频率重合时,将导致车顶网压谐波含量较大从而造成牵引网谐振过电压的出现,通过改变机车变流器斩波频率或供电臂长度可以抑制牵引网谐振过电压。     

智能电网下低压电力线通信的特性研究

提出智能电网环境下的通信方式,并说明低压电力线通信的优点。研究分析了低压电力线通信的时变性、深衰减、多径性、电磁干扰等特点。在分析电力载波通信(power line communication,PLC)原理及特点的基础上,提出利用正交频分复用(orthogonal frequency division multiplexing,OFDM)技术来提高系统的传输性能。对智能电网环境下低压电力线通信技术的应用进行展望,并列举低压电力线通信在超远程抄表、网络连接等方面的应用。     

750 kV同塔双回交流输电线路电磁环境研究

我国西北电网规划的多条750kV交流输电线路位于高海拔地区,无线电干扰和可听噪声等电磁环境问题更加严重。因此,研究750kV交流输电线路电磁环境问题对我国750kV输电工程建设具有重要意义。计算一条典型750kV同塔双回交流输电线路,最大运行电压分别为775.0kV、787.5kV、800.0kV下无线电干扰、可听噪声、线路下方距地面1m水平线上工频电场强度、导线最低对地距离和走廊宽度。按文献给出的电磁环境标准进行讨论,结果表明:通过选择合适的线路参数(导线最低对地距离、海拔高度等),可满足3种最大运行电压下电磁环境指标要求。     

自耦变压器供电方式的电牵引供电系统中的机车驱动谐波污染仿真研究

为了减少电气化铁路对其沿线的通信系统造成的干扰，电牵引供电系统可以采用自耦变压器供电方式。本文分析了此系统中的机车驱动谐波污染情况，建立了SS4型电力机车、牵引网及牵引变电所的模型，并通过MATLAB仿真计算出在多机条件下电力机车、牵引网及牵引变电所中的谐波电流及其谐波含量。     

基于脉冲功率技术的高压电场感应取能设计

针对电力巡线旋翼无人机续航能力不足的问题,提出一种基于脉冲功率技术的高压电场感应取能设计。以巡线无人机机载导体作为悬浮电极,在电力线与架空地线之间高压电场中储存感应电能,级联气体自触发开关和电感,并与架空地线构成取能回路,悬浮电极击穿开关气隙对地放电。随气隙放电发展,悬浮电极与电力线、架空地线间分布电容将迅速分压,抑制放电,使气隙间无法形成电弧,而转为高频流注脉冲放电,激发回路高频电磁振荡,通过电磁互感实现电场感应电能输出。文中详细介绍了脉冲功率电场感应取能设计及抑制放电原理,分析取能等效电路并建立了放电脉冲取能模型,在实验室环境下进行物理平台搭建与测试,实验结果证明设计可行。     

现代电气化铁路供电方案研究

现代电气化铁路供电系统的方案选择对电力机车和地区电网的安全稳定运行都至关重要。从牵引变压器、牵引变电站至牵引网的供电方式、牵引变电站供电电压等级的选择这3方面,对电气化铁路可选的各种方案进行分析比较,并考虑实际应用,选取了目前的最优方案。     

浅析电力机车对牵引网电能质量的影响

电力机车作为牵引网的负载,其产生的谐波会对牵引网造成污染,如果车网关系不匹配,电力机车和牵引网会产生谐振现象,交流电力机车中间直流电压的低频震荡也会引起牵引网电压的震荡,所以电力机车对牵引网电能质量的影响越来越受到重视.介绍了电力机车产生的谐波对牵引网的影响,车网谐振和低频振荡出现时的现象及其解决办法.     

一种无锁相环的单相电路谐波和无功电流检测方法

有功电流分离法是近年来出现的一种单相电路谐波和无功电流检测新方法。在电气化铁路中,电力机车是一个运行的、急剧变化的单相牵引负荷,当由其引起的电网电压波动较严重时,可能导致该检测方法中使用的锁相环处于失锁状态而无法进行准确检测。该文对该检测方法进行简化,提出了一种无锁相环的单相电路谐波和无功电流检测方法。理论分析和仿真证明,该方法可以实时检测出单相电路谐波和无功电流,原理简单、易于实现。     

Electric fields of grounding electrodes with frequency dependent soil parameters

The profile of the electric field developed at the ground level above a horizontal grounding electrode due to the impression to the electrode of waves resembling lightning currents of first and subsequent strokes was calculated using an electromagnetic model. The simulation considered both assumptions constant values for soil parameters resistivity and permittivity and frequency dependent values. This dependence was given by an expression derived from field measurements. It was found that the frequency dependence of soil parameters is relevant, mainly at low conductivity soils and short front-time current waves, leading to a significant decrease of the electric field profile.     

A method for improving the energy efficiency of an alternating current electric locomotive in the regenerative braking mode

A method for improving the power factor of an ac locomotive with the commutator motor operating in the regenerative braking mode is proposed. The method improves the control system algorithm of the power converter. The new switching method of inverter thyristors regulates the curve of the instantaneous power during the main switching. It allows reducing the period in which the energy flow passes to the locomotive, leading an increase in the average value of the instantaneous power. A “traction substation–electric traction network–locomotive in the regenerative braking mode” mathematical model is presented to verify efficiency of the method. The model consists of several interacting electric power substations, a section of electric traction grid, a locomotive power transformer, a four-zone inverter, a control system of reversible converter, and a dc circuit. The model is realized in the OrCAD software.