Electrified Railway Research Articles

Study on Wind-Induced Vibration Behavior of Railway Catenary in Spatial Stochastic Wind Field Based on Nonlinear Finite Element Procedure

Due to its long-span structure and large flexibility, an electrified railway catenary is very sensitive to environmental wind load, especially the time-varying stochastic wind, which may lead to a strong forced vibration of contact line and deteriorate the current collection quality of the pantograph–catenary system. In this paper, in order to study the wind-induced vibration behavior of railway catenary, a nonlinear finite element procedure is implemented to construct the model of catenary, which can properly describe the large nonlinear deformation and the nonsmooth nonlinearity of dropper. The spatial stochastic wind field is developed considering the fluctuating winds in along-wind, vertical-wind, and cross-wind directions. Using the empirical spectra suggested by Kaimal, Panofsky, and Tieleman, the fluctuating wind velocities in three directions are generated considering the temporal and spatial correlations. Based on fluid-induced vibration theory, the model of fluctuating forces acting on catenary are developed considering the spatial characteristics of catenary. The time- and frequency-domain analyses are conducted to study the wind-induced vibration behavior with different angles of wind deflection, different angles of attack, as well as different geometries of catenary. The effect of spatial wind load on contact force of pantograph–catenary system is also investigated.

Study on Pantograph Arcing in a Laboratory Simulation System by High-Speed Photography

Phenomena of the pantograph arcing have become a challenge for the further development of high-speed electrified railway system. Despite of the large attention that has been paid to the radiated electromagnetic interference, materials ablation as well as the power-quality decline resulted from pantograph arcing, the specific dynamics of pantograph arcing with a high time resolution are still in absence. In this paper, the pantograph arcing phenomena in a laboratory simulation system were experimentally studied by high-speed photography. Synchronized electrical voltage and current waveforms were obtained to acquire a more comprehensive understanding on the underlying physics. The overall dynamics of the pantograph arcing from ignition to extinguishment were recorded. Three stages of the electric-contact process, from approaching arc, mechanical contact to the drawn arc, were well distinguished. A much intensified drawn arc was observed than the approaching arc. Typical lasting time of the drawn arcing is found $\sim 4$ times larger than the approaching arcing for our test setup. Maximum diameter of 3.3 mm was reached at around the current-peak moment. An interesting stable arc voltage of $\sim 23$ V was found during the drawn arcing. Intense material splash above the carbon strip was observed during the arcing process. The transient resistance during a typical arcing period was also analyzed, and a minimum value of $\sim 100~\text{m}\Omega $ was determined.

Detection of Contact Wire Irregularities Using a Quadratic Time–Frequency Representation of the Pantograph–Catenary Contact Force

As for the rapid expansion of high-speed electrified railway industry, the current collection quality of electric locomotives becomes one of the crucial technical issues for the stable operation of trains. The key measurement index that can characterize the quality of current collection is the contact force between the catenary and pantograph on the locomotive roof. One of the major factors that affect the contact force is the contact wire irregularity, which appears to be very difficult to be measured or detected at present. In recent years, the frequency-domain indicators of the pantograph–catenary contact force (PCCF) have been gaining importance to address this issue. In this paper, a recent quadratic time–frequency distribution is selected to describe the time–frequency representation (TFR) of PCCF signal based on its nonstationarity. The Zhao–Atlas–Marks distribution (ZAMD) shows high time–frequency resolution and cross-term suppression for PCCF signals. To investigate the deterioration of the PCCF under contact wire irregularity, a pantograph–catenary interaction model is presented and verified. Some synthetic contact wire irregularities are generated and added to the interaction model. Based on the characteristics of quadratic TFRs of PCCF signals, a detection and localization approach for contact wire irregularity is proposed in this paper. The simulation and real-life experimental results indicate that the different forms of contact wire irregularity could be effectively detected and localized with meter accuracy using the ZAMD.

A Railway Traction Power Conditioner Using Modular Multilevel Converter and Its Control Strategy for High-Speed Railway System

With the development of high-speed and high-power electrified railway, power quality of traction power grid becomes more serious. In order to achieve three-phase balance of traction power grid, a modular multilevel converter (MMC)-based railway traction power conditioner (RTPC) is studied, which is characterized by modular multilevel cascaded structure. The RTPC consists of four H-Bridge links and output filter inductors, which can be connected to 27.5-kV traction feeders in co-phase supply system directly. This conditioner can be used for different kinds of traction system, especially suited to Scott traction system. According to the analysis of equivalent electrical model and power balance of RTPC, a hierarchical control strategy is put forward aiming to balance the submodule capacitor voltages, which ensures the safety and stability of system. Finally, the structure and its control strategy are verified by the simulation and experiment effectively.

Problems of electromagnetic compatibility in electricity of rail system

Problems of electromagnetic compatibility on electrified railways are sharper than in the stationary energy sector. This is due to the following circumstances: 1. Electrified railways has considerable length in space and is usually located in different climatic and in geological zones. 2. In rail transport, as well as any other transport systems, a compact high-performance equipment used (high and low voltage), to a greater degree of exposure to external electromagnetic influences than in the stationary energy sector. 3. All processes (stationary and non-stationary) on an electrified rail, in one way or another, affect the operation of each of the elements of the system. 4. In the development of an extensive electrified railway is necessary to ensure the electromagnetic compatibility of each of the elements that are not always required in the stationary energy sector. 5. Problems of electromagnetic compatibility electrified railways significantly of more complicated, when are using magnetolevitatsionnyh technologies for elektrozhdvizhenie. Considered the problems of electromagnetic compatibility in electricity of rail system, are discussed ways of solving them.

Based on the Safe Operation of Electrified Railway Traction Power Supply Research of Harmonic Suppression

According to the base function and harmonic wave voltage separate effect of different mathematical model is set up the extension of the hybrid filter respectively. In the MATLAB environment, the paper analyzes the active filter effectively restrain system to the power grid impedance of the series-parallel resonant characteristics of passive power filter device and tolerance sensitivity of quality factors. Conclusion: capacitor tolerance have bigger influence on the quality factor. And through the programming into hybrid filter above build simulation module, the simulation is to get ideal effect of reactive power compensation and harmonic suppression.

On the man-made contamination on ULF measurements: evidence for disturbances related to an electrified DC railway

Abstract. An analysis of measurements performed at L'Aquila (Italy) during a deep minimum of solar and magnetospheric activity (2008–2010) allowed for the evaluation of possible contamination of the ultralow-frequency (ULF) spectrum (f ≈ 1–500 mHz) from artificial disturbances, practically in absence of natural signals. In addition, the city evacuation and the interruption of all industrial and social activities after the strong earthquake of 6 April 2009 allowed also for the examination of possible changes of the contamination level under remarkably changed environmental conditions. Our analysis reveals a persistent, season-independent, artificial signal, with the same characteristics in the H and Z components, that affects during daytime hours the entire spectrum; such contamination persists after the city evacuation. We speculate that the DC electrified railway (located ≈ 33 km from the Geomagnetic Observatory of L'Aquila, it maintained the same train traffic after the earthquake) is responsible for the observed disturbances.

Short-term Forecast Technology in Load of Electrified Railway based on Wavelet-extreme Learning Machine

With the development of economy and the progress of science, the proportion of electrified railway load in the power gird has been keeping on increasing, which impacts the short-term forecasting in load a lot, therefore, it is very important to analyze short-term load of electrified railway forecasting. This paper analyzes the power gird load-forecasting considering the influence of the electrified railway load, and introduces wavelet mechanism for data processing based on the research of electrified railway load. The wavelet-extreme learning machine algorithm is proposed and used in the short-term forecast in load of electric railway on the platform of MATLAB. The application in the local electric power company indicates that the wavelet-extreme learning mechanism model has the features of accurate prediction, quick response, and strong practicability

Arc erosive characteristics of a carbon strip sliding against a copper contact wire in a high-speed electrified railway

Experimental studies on arc erosive characteristics of a carbon strip rubbing against a copper contact wire were carried out on a ring-on-block electrical sliding tester. The test result shows that the intensity of arc discharge has a significant influence on friction and wear performance. These arc erosive characteristics are characterized by two special traces. SEM examination shows that arc erosion and oxidative wear caused by arc discharge are the main wear mechanisms. This indicates that the off-line arc discharge of the contact couple should be suppressed to the maximum extent to extend the service life of the pantograph strip in high-speed electrified railways.

A New Contactless Fault Diagnosis Approach for Pantograph-Catenary System Using Pattern Recognition and Image Processing Methods

Comfort and safety of railway transport has become more important as train speeds continue to increase. In electrified railways, the electrical current of the train is produced by the ...

Based on the LabVIEW Electrified Railway Signal Acquisition and Processing System of Electromagnetic Radiation

Electrified railway got rapid development in recent years, increasingly highlights its electromagnetic compatibility problems. In this paper, on the basis of predecessors' research results, the virtual instrument technology is applied to the electromagnetic radiation of electrified railway signal measurement, complete embedded processing equipment design, make its have the electromagnetic radiation on the railway signal detection, acquisition and processing functions. Based on LabVIEW embedded development environment configuration and Windows CE operating system builds and transplantation, realize the man-machine interface easy to operate and flexible signal processing algorithms.

Research on On-Line Anti-Icing Technology for Carenary along Electrified Railway

Accidents of icing on catenary have great impacts on normal operation of trains. An on-line anti-icing technology used static var generator (SVG) for catenary was proposed, which can prevent icing formation without interrupting trains normal operation. The heat balance equations for catenary were solved, whose results were compared with data provided by TB/T 3111 and testing show the equation was correct. The simulation model based on Matlab was bulit , whose results and analysis show the correctness of the method.

Impact Analysis and Testing of Harmonic of Electrified Railway on Energy Metering

This paper analyzed the characteristics of electrified railway power supply combine of the status quo on electrified railway power supply and energy metering. According to the metering principle of the electrical energy meter, this essay theoretically analyzed the impact of harmonic of electrified railway on energy metering. By comparing the analytical laboratory and field test data, the adverse influence of harmonics generated by electrified railway power supply on energy metering is studied and come to a conclusion that the electrified railway user is less metered the power while the linear user is more metered.

Fundamental Study on Saving Energy for Electrified Railway System Applying High Temperature Superconductor Motor and Energy Storage System

Induction motor instead of dc one has been applied widely for dc electric rolling stock because of the advantage of its utility and efficiency. However, further improvement of motor characteristics will be required to realize environment-friendly dc railway system in the future. It is important to study more efficient machine applying dc electric rolling stock for next generation high performance system. On the other hand, the methods to reuse regenerative energy produced by motors effectively are also important. Therefore, we carried out fundamental study on saving energy for electrified railway system. For the first step, we introduced the energy storage system applying electric double-layer capacitors (EDLC), and its control system. And then, we tried to obtain the specification of high temperature superconductor induction/synchronous motor (HTS-ISM), which performance is similar with that of the conventional induction motors. Furthermore, we tried to evaluate an electrified railway system applying energy storage system and HTS-ISM based on simulation. We succeeded in showing the effectiveness of the introductions of energy storage system and HTS-ISM in DC electrified railway system.

Design and Application of Var Compensation Method for Traction Power Supply Systems of Electrified Railway

The application of electric power, which acts as a pillar energy and economic artery in modern society, is one of the most important symbols of the level of development and comprehensive national power of a country. Var is a crucial factor for the design and operation of AC power systems, and is closely bound up with the safety, stabilization, and economical operation of power systems. With the development of electrified railway, the importance of the dynamic var compensation for traction power supply systems of electrified railway becomes more and more distinct. Developing the var compensation strategy vigorously has important senses in theory and practice. In this article, synthetically considering technique and economic leval of power systems in our country, parameters modeling and design and verification and specific engineering application of a var compensation method are presented. This method is a preferable one for resolving undesirable effect on power systems from traction power supply systems of electrified railway, especially having dynamic and real time characteristics of var compensation.

Fixed Energy Storage Technology Applied for DC Electrified Railway

AbstractThe fixed energy storage system solves the problem of rising energy costs by reducing primary energy consumption. Without a fixed energy storage system, the energy generated by a braking vehicle would be simply converted into waste heat by its braking resistors if no other vehicles are powered simultaneously. Because, as a rule, such synchronized braking and powering cannot be coordinated, the energy storage system stores the energy generated during braking and discharges it again when a vehicle is powered. This greatly reduces primary energy demand in the substation. However, in addition to this energy saving, the energy storage system contributes to the reduction of CO2 emissions. The energy storage system also stabilizes the system voltage. Recent years have witnessed an advance in the energy storage media technology. Developments of energy storage media, lithium ion battery, nickel‐metal hydride battery, and electric double‐layer capacitors (EDLCs) have been remarkable. This study introduces technologies of fixed energy storage system applicable for DC electrified railway in Japan, and describes two examples of charge/discharge characteristics. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A Method for Interfacing Lumped-Circuit Models and Transmission-Line System Models With Application to Railways

Transient analysis of lossy multiconductor transmission lines (MTLs) has been studied using the finite-difference time-domain (FDTD) method with lumped loads/devices connected at line terminations. In electrified railway networks, series and shunt devices (whose circuit models are derived either from experiments/borrowed off the shelf), e.g., transformers, converters, switchgear, signal equipments, etc., are found distributed along the MTL system. To simulate such railway systems involving both transmission lines (TLs) and lumped circuits, an interface technique between TL systems, which is solved using FDTD, and all the lumped circuits, which are solved using alternative transients program/electromagnetic transients program software (circuit solver), is proposed. This sufficiently accurate method is simple to apply as only instantaneous voltages and currents are transmitted between the stand-alone FDTD routine and circuit solver. Moreover, the user avoids coding complex circuit models within the FDTD, while at the same time, efficiently uses the potential of accurate frequency-dependent loss models (nonexistent in circuit software) coded in FDTD. The technique is applied on typical electrified railway systems to demonstrate how traction transformers, track circuits, and line interconnections affect the propagating voltages and currents. The method could be beneficial for transient protection and insulation coordination studies in electrified railway systems.

Vulnerability of European Rail Traffic Management System to Radiated Intentional EMI

In this paper, the vulnerability of the future electrified railway system in Europe from a high-power microwave (HPM) source is investigated. The scenario of in-band disturbances radiated toward a GSM-R antenna and damaging the connected communications system is evaluated for different classes of HPM sources and situations. The minimum realistic distances for the different HPM sources from the antenna to cause permanent damage is shown, and the severity of threat from the different sources is discussed.

Sliding wear behavior of copper alloy contact wire against copper-based strip for high-speed electrified railways

This paper reports the study of the sliding wear behavior of the Cu–Ag–Cr wire. Cu–Ag–Cr alloy is a promising contact wire material for high-speed electrified railways, which has an excellent combination of mechanical strength and electrical conductivity. Wear tests were conducted under laboratory with a special sliding wear apparatus, which simulated the tribological conditions of sliding current collectors on overhead wires in the railway system. The Cu–Ag–Cr alloy wire was slid against a copper-based powder metallurgy strip under unlubricated conditions. The same strip as those in the train systems were used. Worn surfaces of the Cu–Ag–Cr alloy wire were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDS). Within the studied range of electrical current, normal pressure and sliding speed, the wear rate increased with the increasing electrical current and the sliding distance. Compared with a Cu–Ag contact wire under the same conditions, the Cu–Ag–Cr alloy wire had much better wear resistance. Adhesive wear, abrasive wear and arc erosion were the dominant mechanisms during the electrical sliding processes.

Evaluation of Maintenance Schedules on Railway Traction Power Systems

In electrified railways, the traction power systems carry power to trains and their reliability is vital to the quality of train services. There are many components in the traction power system, from interface with utility distribution network to contacts with trains, and they are physically located along the rail line. Subject to usage, environment, and ageing, conditions of components deteriorate with time. Regular maintenance has to be carried out to restore their conditions and prevent them from failure. However, the decisions on the suitable length of maintenance intervals often lead railway operators to the dilemma of minimizing both risk of failure and operation cost. On the basis of a stochastic lifetime model, this article presents a generic software evaluation tool that enables the operators to manage risk of failure and cost quantitatively in order to match their preferred levels of service quality. The lifetime model includes the effects of condition restoration because of maintenance of regular intervals and ageing acceleration because of electrical stress from traffic demands. Examples of simulation results are given to illustrate the applicability of this lifetime model.