Overhead Contact Wire Research Articles

Modeling of electromagnetic influences of multi-wire traction networks for pipelines

In this work, digital models for determining the electromagnetic influences of multi-wire traction networks on pipelines are developed. When developing models, an approach based on multiphase behaviour simulation of electric power systems was used. This approach adequately addresses all the influencing factors, which include modules and phases of currents flowing through the overhead contact wire suspension, 6–10–25 kV power transmission lines laid on the supports of the overhead line, and lines of rails. In addition, it is possible to take into account similar parameters for stresses at the nodal points of a multi-wire system. Among the key factors are the railway clearance when laying pipes parallel to the railway track, railway clearance trajectory in the presence of non-parallel sections, and the electrical characteristics of the soil along the clearance route. The research results demonstrated that a 25 kV electromagnetically unbalanced traction network exerts significant influence on a pipeline running in parallel. It was shown that the maximum induced voltages at specific points along the pipe fall within the range of 300–700 V, which significantly exceeds the permissible level of 60 V. It was revealed that currents exceeding 20 A flowing through the pipe can have an adverse effect on anticorrosive protection devices. To mitigate electromagnetic impacts on the pipeline, the following measures are recommended: reducing the length of pipeline and railway clearance sections, increasing the gap between the traction network and the pipe, and installing an additional grounding source. The pipe can be connected to the supplementary grounding source through filters tuned to a frequency of 50 Hz, which involve capacitor units to prevent malfunctions during the operation of pipeline protection devices. Thus, the developed digital models allow the induced voltages generated by multi-wire traction networks and the currents flowing through the pipes to be adequately determined. These models offer an informed choice of measures that ensure the safety of pipeline maintenance.

Development Method of Fully Automatic Wire Winding Device Based on Dual Motion Control System

In the construction of overhead contact wire for electrified railways, the entire process of wire drawing is manually made, especially for the winding and fixing of the back tie wire. With the length of construction lines often reaching hundreds or even thousands of kilometers, the task of wrapping and fixing the back tie line becomes very heavy and cumbersome. In addition, whether the entanglement is firm, tightly attached, and smooth greatly tests the wrist strength and craftsmanship of construction workers. The comparison between teachers and beginners in construction is obvious, and it is difficult to ensure the consistency of construction standards. In response to the above issues, the fully automatic winding machine adopts a mechanical dual transmission design, a mechanical moving slide mechanism, a reduction motor, and a stepper motor control system to achieve winding process standards such as tight adhesion, reliability, and smoothness, and improve manual operation efficiency by 3-5 times.

Contact wire position measurement on trolley-based system using 3D Laser-Scanning with geometric constraint method

The position of overhead contact wire (POCW) is a critical technical parameter for electrified rail transportation systems, and should be measured using contactless approaches. Although various contactless POCW measuring systems have been developed, their limited accuracy and insufficient coverage remain challenges. This paper presents a novel trolley-based system for efficient and accurate POCW measurement. This system integrates the POCW measurement system with an inertial track geometric measurement system, which can be used to measure the absolute POCW. The proposed system uses 3D laser-scanning with a line profiler (3D-LLP) and a robust POCW estimation method to overcome ambient light, speckles, and reflections. The estimation method employs a least-squares circle fitting technique utilizing prior OCW information and geometric photographic constraints. Laboratory and railway experiments demonstrate the system's robustness, accuracy, and precision. Some prospects were proposed for further improving the measurement performance.

Traction capacity of rechargeable LFP batteries for trolleybus

The article deals with the actual problem of reducing air pollution by internal combustion engines of public transport in urban and suburban traffic through the use of battery trolleybuses for passenger transportation. A method is proposed for calculating the capacity of batteries for the autonomous movement of trolleybuses, which can be used to calculate the required capacity of trolleybus batteries for use on city bus routes partially passing under the trolleybus overhead contact wires. The calculation of the required capacity of the lithium iron phosphate (LFP) battery for the operation of the battery trolleybus on the real bus route of the Chisinau municipality has been carried out.

A Study of Generalized Hybrid Discrete Pantograph Equation via Hilfer Fractional Operator

Pantograph, a device in which an electric current is collected from overhead contact wires, is introduced to increase the speed of trains or trams. The work aims to study the stability properties of the nonlinear fractional order generalized pantograph equation with discrete time, using the Hilfer operator. Hybrid fixed point theorem is considered to study the existence of solutions, and the uniqueness of the solution is proved using Banach contraction theorem. Stability results in the sense of Ulam and Hyers, and its generalized form of stability for the considered initial value problem are established and we depict numerical simulations to demonstrate the impact of the fractional order on stability.

Technology of the Contact Wire Manufacture for High-Speed Railways

The article presents an overview of possible technological schemes to produce an overhead contact wire for railways. Pilot experiments were carried out on the manufacture of a contact wire made of CuMg0.3, CuMg0.4 and CuMg0.5 alloys and having a nominal cross section of 100 mm2. The contact wire was obtained from a continuously cast rod with small section, which was subjected to plastic deformation using the Conform technology and cold drawing of the extruded rod. In the casting process, we encountered the formation of cracks on the cast rod surface and the rods breakage. The inner surface of the graphite bushings of the mold after casting the rod was studied and a thin gray layer was found on the inner surface of the graphite bushings. Areas of the graphite bushing with gray layer were studied by scanning electron microscopy and element-by-element mapping was performed with the selection of a spectrum in the sediment layer area. In order to determine the phase composition of the sediment layer it was analyzed by the method of full-profile analysis of the X-ray diffraction pattern according to Rietveld. X-ray phase analysis showed the CuMg2 and Cu2Mg phases presence. This allowed us to assume a possible mechanism for the formation of the sediment layer. Ultimate tensile strength, elongation and electrical resistivity was determined. Analysis showed that the overhead wires made of CuMg0.3, CuMg0.4, CuMg0.5 alloys meets the requirements of GOST R 55647-2018 for wires made of the second conditional group bronze.

To the Issue of Low-Alloyed Copper Alloys for Contact Wires

This paper is about a comparative analysis of the requirements of the Russian standard, the standard of the European Union and the PRC for overhead contact wires for electrified high-speed railways. New generation contact wires must have a high level of mechanical, electrical and operational properties. The Russian standard does not regulate the chemical composition of alloys used for the contact wires manufacture. Unlike the standards of the European Union and China, the Russian standard regulates the maximum value of the relative creep. Compositions, mechanical properties, electrical resistivity and recrystallization temperature for the contact wires with a cross section of 120 mm2 are given. The requirements for the material for the contact wire are presented. The need to use more durable conductive materials instead of copper is noted since mechanical loads and operating temperatures are constantly increasing. The values of mechanical properties, recrystallization temperature and creep of contact wires made of copper alloys are given. Based on the analysis results of the literature data and the experiments, alloys of the Cu-Mg system are recommended as a material for the contact wire manufacture for an overhead network system for high-speed railways.

Implementation of Implantation-Stagger Measuring Unit using Image Processing

The electrical traction system of railways is a combination of physical upright structures and OCL(Overhead Contact Lines). The horizontal distance from the center of the track to the OHE mast called implantation, horizontal displacement of overhead contact wire with respect to the center of the railway track called stagger, and the perpendicular height of overhead contact wire from the ground are periodically checked by a lineman in order to ensure a safe distance from the railway track. In this paper, we have put forth an idea of building a distance measuring device to measure the implantation and stagger without touching the objects using Open CV on raspberry pi with a camera module which will be placed at the center of the track. The system will be having two features. To measure the distance of the nearest poles, the camera has to be placed facing the mast perpendicular to a circle of diameter appropriate which is placed on the pole for measurement purposes. And to measure the stagger, the camera has to be placed facing the overhead wire from the center of the track.

Railway overhead contact wire monitoring system by means of FBG sensors

Safety of infrastructures represents one of the most significant concerns for governments and service providers to preserve people's well-being. One of the main ways to keep in safe facilities (buildings, bridges, railways, etc.) involves the use of monitoring sensor systems in charge of measuring critical operating conditions. Those measurements together with periodical maintenance, contribute to minimize potential risks that the infrastructure faces. The paper aims at designing, developing, and testing a monitoring system for mechanical stresses acting on the overhead contact wire (OCW) to ensure the operational safety of the railway network. In this regard, the paper proposes two Fiber Bragg Grating (FBG) sensors-based solutions, relying on the ability of these sensors to allow real-time and continuous data acquisition. The first one consists in a polyimide-coated sensor bonded on an OCW clamp, the second one is a copper-coated sensor hanging between the two separated halves of an OCW clamp. Significant results have been obtained mechanically testing both solutions, trying to simulate the operative conditions.

Generation Mechanism of Localized Wear of Cu-impregnated Carbon-based Pantograph Contact Strip

Localized wear of pantograph contact strips is a significant problem affecting the current-collecting systems in electric railways, because it may cause fusion of the pantograph head, resulting in devastating damage to the overhead contact wire. However, the causes of localized wear of carbon-based contact strips have not been clarified, and thus, effective prevention measures cannot been established. The purpose of this study is to clarify the generation mechanism of localized wear in copper-impregnated carbon-based contact strips. In this study, the actual locally worn strips were analyzed with a micro Raman spectrometer. The sliding wear behavior of contact strips with different degrees of graphitization of the carbon substrate was investigated using a block-on-ring-type wear tester.

Far-Field Earthquake Responses of Overhead Line Equipment (OHLE) Structure Considering Soil-Structure Interaction

Overhead line equipment (OHLE) is the components for the electric train which supply the electric power to the train. For one or two tracks, OHLE is normally supported by cantilever mast. The cantilever mast, which is made of H-section steel, is slender and has a poor dynamic behaviour by nature. Nonetheless, the mast structures, which located alongside the railway track, have not been fully studied on the dynamic behaviour. This paper presents the effects of far-field excitations on cantilever mast and overhead contact wire. The five far-field earthquake records at various magnitudes between 6.5 and 8 Mw are considered. A three-dimensional mast structure with varying support stiffness is made using finite element modelling. It is interesting that support stiffness plays a role in the dynamic responses of OHLE during far-field earthquakes due to the change of its properties. Surprisingly, the earthquakes can cause damage to the overhead contact wire which lead to the failure of electric system. In this case, the train cannot run until the broken wire and electric system is cleared. This occurs when there are the losses of support stiffness due to the failure of support connection or soil degradation. Moreover, beating phenomenon, which normally occurs in the tall building, is obviously observed in OHLE during the occurrence of earthquake. This is the world first to demonstrate the effects of far-field earthquakes on the cantilever mast structure and the response of OHLE. The insight in this earthquake response of OHLE and its support has raised the awareness of engineers for better design of cantilever mast structure and its support condition. The outcome of this study will provide a new earthquake detection method using OHLE.

Analytical investigation of railway overhead contact wire dynamics and comparison with experimental results

Abstract In this paper an analytical method for studying the free response of continuous vibrating systems with distributed and possibly non-proportional viscous damping is proposed. The most general case the method refers to is a piece-wise homogeneous Euler-Bernoulli beam, with lumped elastic and inertial elements and subjected to tensile load. The practical application of the method to a contact wire is also presented, aiming at analysing its dynamic response. Contact wires are typically used in the overhead contact line of the railway electrification system but, despite their wide diffusion, their damping properties have not been exhaustively studied. This study aims at experimentally validate the analytical method to define a reliable dynamic model of overhead contact lines. The wire is modelled as an axially loaded homogeneous beam, with lumped elastic and inertial elements (i.e. droppers and clamps). A state-form expansion applied in conjunction with a transfer matrix technique is adopted to extract the eigenvalues and to express the eigenfunctions in analytical form. Experimental measurements have been carried out in the Dynamics & Identification Research Group (DIRG) laboratory of Politecnico di Torino considering two different damping scenarios, and the modal properties of the test bench have been extracted by using a linear subspace identification technique. The damping distribution is finally investigated starting from the experimental data, in order to seek for the most appropriate damping model.

Vibrations of the overhead catenary caused by the passage of a high-speed train through the track stiffness discontinuity

The paper presents the methodology for simulating vibrations of the railway catenary, caused by the passage of the train through the track stiffness discontinuity. The concept of the simulation algorithm takes into account the dynamic interaction between pantographs and the overhead contact wire as well as nonlinearity resulting from the specificity of the droppers behaviour, which do not carry compression - they only carry tensile forces. The coupling of track and rail vehicles vibrations is also included. According to physics, the effect of vibrations of the catenary carried by pantographs on the railway vehicle was not taken into account, which allowed to divide the simulation algorithm into two stages and develop two computer programs with a defined hierarchy of operation. In the first stage of the simulation, the time-histories of vibrations and vibration velocities of those train cars, on which the pantographs are mounted, are calculated. In the second stage, the previously calculated time-histories are set as the input data and the vibration characteristics of the catenary and contact force between pantograph and the contact wire are calculated. The paper presents examples of vibration simulations of a rail vehicle observed in real time at the theoretical point of the pantograph base. The results of the second stage of the simulation were also shown: selected vibration time-histories of the pantograph and the five-span section of the catenary, and oscillations of the contact force between pantograph and the contact wire. The impact of the track stiffness discontinuity on catenary vibration was assessed.

A mobile catenary power supply system for automotive vehicles

Trolleybus type power supply using a two-pole overhead catenary system has been used for over one hundred years. However, energy demand in this type of road transport is the lowest. The main disadvantage of this type of transport is the lack of flexibility. Road electric vehicles equipped with batteries, which are now more and more often being put into service, allow for autonomous run on the roads without overhead contact wires. Therefore, it is possible to use them in a more flexible manner. The main problem is a limited range of autonomous run and long charge time of batteries. The paper presents a concept consisting in the application of an overhead catenary for supplying electric and hybrid vehicles (including automobiles) when a vehicle is in motion (mobile charging). Electric trucks are equipped with controlled current collectors allowing for connection with an overhead catenary during driving. Application of this solution to automobiles is rather impossible, which prevents them from being supplied directly from a catenary. The basis of the original concept presented in the paper is the creation of automobile convoys supplied via a truck equipped with current collectors. A description of the proposed system and an algorithm of its operation are presented in the paper. The discussed transport system has significant advantages in comparison to completely autonomous electric vehicles: increased range of driving with lower capacity of batteries on board and flexibility of use, longer life-time of batteries, lower energy consumption. The paper compares the proposed system with the currently used ones, which employ charging of automobiles during stops, but also underlines the advantages of the first solution.

직류철도 급전계통의 안전성 향상을 위한 차단기 동작 최적 설정의 실험적 고찰

This paper presents an experimental study on the optimal settings for the selected DC fault relay (50F) to improve the operating performance for the high-speed circuit breaker on DC feeding system which ensure safety within rolling stock maintenance depot. In this study, current supplied to overhead contact wire was calculated on 1 ms interval to analyze the correction values of DC fault selective relay for the operation of current supply cutout. Particularly, standards for the accurate detection of accidents between an electric railway vehicle and the electric power facilities are shown by investigating the optimal correction values for detection of fault current, and the results indicated that it takes about 213 ms for the DC fault selective relay(50F) to fully open. In the future, the correction values of DC fault selective relay suggested in this paper will be used as the reference values of protective relay for the safe operation of DC electric railroad system such as urban railway.

A new approach based on firefly algorithm for vision-based railway overhead inspection system

The maintenance of the pantograph–catenary system is a crucial problem in railway inspection systems. The quality of current collection depends on maintaining good contact between a moving pantograph and an overhead contact wire. Problems in the current collection system lead to the damage and disruption of railway traffic. Pantograph arcing occurs between the pantograph and the overhead wire because of the wear of the contact strip. This paper proposes an automatic inspection system for detecting the pantograph and arcs that occur using a firefly optimization algorithm. The proposed method is able to localize the pantograph as a rectangular region and detect the burst of arcing under different illumination and weather conditions simultaneously. The firefly algorithm based Otsu method is used to detect arcs that occur in this region. The proposed approach can serve as an automatic monitoring system and can detect the occurrence of arcing due to loss of contact. The proposed method was applied to four real pantograph videos and efficient results were obtained.

The Study of Arc Rate, Friction, and Wear Performance of C/C Composites in Pantograph–Catenary System

A series of tests on arc rate, friction coefficient, and wear rate of electrical current collectors sliding against overhead contact wires under different conditions was carried out on a high-speed friction and wear testing machine with a pin-on-disc configuration. The worn surface morphology and composition were examined using a scanning electron microscope and energy dispersion spectrum analyzer, respectively. The effects of current, velocity, and load on the arc rate, friction coefficient, and wear rate of C/C composites/QCr0.5 couples were investigated, and the influence mechanism of test parameters on C/C composites was explained. It is concluded that the wear rate increases with an increase in current and velocity and has a decreasing trend with the increase in load. The friction coefficient increases with an increase in velocity and load. The arc rate of C/C composites/QCr0.5 couples increases with an increase in current and velocity. Under the condition of the same current and velocity, when the load is 70 N, the arc rate is the lowest.

전차선의 집전상태 판단 알고리즘 구현

Analyzing dynamic performance between pantograph and contact wire depends on mechanical and electrical conditions such as contact force, currents, aerodynamics of pantograph and tension of overhead contact wire. For the characteristic of dynamic performance between pantograph and overhead contact wire, various evaluation systems are used to measuring of the interaction of the contact line and the pantograph. Among the various methods, the contact force and percentage of arcing are intended to prove the safety and the quality of the current collection system on the train. However, these methods are only capable of measuring on the train which are installed measurement systems. Therefore in this paper, a track-side monitoring system was implemented to measure electrical characteristics from active overhead contact wire systems in order to constantly estimate current collection performance of railway operation. In addition, a method to analyze loss of contact phenomena was proposed. According to simulation results, the proposed system was capable of measuring abnormal electrical behavior of pantograph and contact wires on the track-side. The advantage of the proposed system is possible to detect loss of contact or any other electrical abnormalities of all types of trains within sections from sub to sub without the need to install any on-board equipment on trains.

팬터그래프와 전차선간 최소 이선아크 지속시간에 따른 이선율 변화량 분석

Quality criteria for interaction between a pantograph and overhead contact wire is a most important requirement to assess of the performance for the current collection system. Interaction performance between pantograph and catenary system is subject to approval by the infrastructure manager when a new design and contraction of overhead contact line and pantograph are installed. Among the various performance, percentage of arcing at maximum line speed is a simple test method compared with contact force of pantograph due to direct sensing of pantagraph, calibrations, installations of train, and etc. On the other hand, percentage of arcing is need to reliable arcing detector and general requirements with accordance with EN 50317. In this paper, percentage of arcing are investigated on the function of duration of arc and proposed which is satiable of percentage of arcing. As a results, we proposed which duration of arcs are unsuitable from infrastructures point of view as performance testing for quality of current collection.

Preparation of Cu–Cr–Zr alloy billets by horizontal electromagnetic continuous stirring

The addition of Cr and Zr into the Cu base is applied to overhead contact wires and lead frames due to its high tensile stress and electrical conductivity. Results show that the length of 45 m for Cu–Cr–Zr alloy billets can be successfully prepared by horizontal electromagnetic continuous stirring. The optimised parameters on Cu–Cr–Zr billets with 87 mm diameter are as follows: the current is 50 A, the frequent is 30 Hz and the casting speed is 108 mm min−1. The rotating magnetic field (RMF) can decrease the casting temperature by 22°C. The average grain size with RMF is 1·35 mm, reduced by 55% compared to that without RMF. The tensile stress is 212 MPa, and elongation is 33%. The microstructure with RMF on non-vacuum casting is similar to that of the vacuum. At the same time, RMF makes Cr, Zr and Cu atoms uniformly distributed.