Current Railway Research Articles

Consideration of the influence of supports in modeling the electromagnetic fields of 25 kV traction networks under emergency conditions

Single-phase 25 kV traction networks of electrified alternating current (AC) railways create electromagnetic fields (EMFs) with significant levels of intensity. The most intense magnetic fields occur when short circuits exist between the contact wire and rails or ground. Despite the short duration of exposure, they can adversely affect electronic devices and induce significant voltages in adjacent power lines, which is dangerous for operating personnel. Although numerous investigations have focused on modeling the EMF of traction networks and power lines, the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be resolved. In this case, the field has a complex spatial structure that significantly complicates the calculations of intensities. This study proposes a methodology, algorithms, software, and digital models for determining the EMF in the described emergency scenarios. During the modeling process, the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic fields. This approach was implemented in the Fazonord software, and the modeling results show a substantial increase in EMF levels close to the support, with a noticeable decrease in the levels as the distance from it increases. The procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited length. Based on the proposed procedure, the EMF near the supports of overhead power lines and traction networks of various designs could be determined, the EMF levels at substations can be calculated, and the influence of metal structures located near traction networks, such as pedestrian crossings at railway stations, can be considered.

Integration of BIM Tools for the Facility Management of Railway Bridges

Current railway infrastructure maintenance work, which is mostly carried out by visual inspection, has a reactive approach, dissociated information, and limited follow-up. On the other hand, railway bridges, being critical infrastructures, require effective monitoring and maintenance to guarantee their safety and operation over time. The designed tool links a parametric BIM model in Revit® with an automated spreadsheet in MS Excel® through visual programming in Dynamo, generating BIM/data automation as an initial step towards a digital twin. This achieves a bidirectional flow to exchange data on the structural condition of elements. The procedure was applied to a railway bridge in use for over 100 years, representing its geometry and damage information according to technical standards. The value lies in laying the foundations for adopting preventive approaches for this key infrastructure. The BIM/data automation allows the BIM model to visually reflect the condition of the elements, depending on their damage, consolidate the inspection information, and generate a visual management tool. In conclusion, the designed BIM/data automation improves the monitoring of railway bridges compared to traditional methods, facilitating the interaction and relationship between the damage records and the actual bridge elements, laying the foundations for the construction of digital twins.

INCREASING THE RELIABILITY OF THE SYSTEM OF AUTOMATIC VOLTAGE REGULATION OF LOW-VOLTAGE CIRCUITS OF ELECTRICAL DIRECT CURRENT MOVEMENT COMPONENTS

Purpose. The purpose of this work is the analysis of possible directions for improving the performance indicators of electric rolling stock of direct current railways. The work is devoted to the improvement of systems of automatic voltage regulation of low-voltage circuits where the power source is a direct current generator. The number of electric locomotives and electric trains of railways and their units, which have exhausted their service life, but will be in service for a long time, preserves the relevance of research into possible directions of modernization and the specifics of system operation. Methodology. The work uses the analysis and generalization of previously performed research. The methodological basis of the research is the mathematical apparatus of the theory of automatic control and the theory of reliability. The object of research is the process of functioning of low-voltage control circuits of electric rolling stock of direct current railways with direct current generators as an energy source. The subject of the study is a voltage regulator for own needs based on a modern element base. Findings. A variant of the system of automatic voltage regulation of low-voltage circuits with generator power sources for electric rolling stock of direct current is offered. The basis of the system is the voltage regulation node, which in the existing structure is made on the basis of a carbon vibration regulator on a strip. As an alternative, a system based on operational amplifiers and the use of proportional or proportional-integral laws of the regulator in the structure is proposed. Modeling of dynamic processes indicates the structural stability of the system and qualitative transition processes. A comparison of the no-failure indicators of the nodes indicates a possible increase in terms between services and cost savings. The comparison is made for systems that are in operation for a long time and those that are offered. Originality. It is proposed to implement the node of the system of automatic voltage regulation on a modern elemental basis, which allows to improve the reliability of the system and implement a small, economical, modernization of rolling stock of railways with an exhausted service life. Practical value. The obtained results can be used by enterprises that carry out major repairs of electric trains and direct current electric locomotives with extended service life. The implementation of the proposed units makes it possible to replace existing contact-based relay systems with fast contact wear, frequent maintenance and debugging. As a result, new units can be transferred to service during current repairs due to the introduction of non-contact systems and increase the probability of trouble-free operation and use the personnel who are always present in locomotive depots. This reduces the cost of maintenance due to the introduction of a modern element base and exclusion from the technological process of maintenance of existing units.

Sediment transportation by strong winds over Gobi surfaces: Field observations along the Lanzhou–Xinjiang high‐speed railway

AbstractUnder strong wind action over vast Gobi surfaces, eolian transportation can cause significant environmental problems and infrastructural damage. However, scientific understanding of the underlying mechanisms and dynamics of this process in the Gobi region remains limited. To address this gap, our study focused on investigating eolian transportation over the Gobi surface along the Lanzhou–Xinjiang high‐speed railway (LXHSR) in Northwest China, where strong winds are prevalent. The results indicate that sand transportation heights can reach 9 m in this region, with the saltation layer approximately 3–6 times higher than that of other gravel deserts. The sediment flux density over the Gobi surface exhibited an exponential decrease with increasing elevation; however, the grain‐size vertical profile in wind‐blown sand displayed an increase up to a critical altitude, followed by a decrease with height. The annual eolian transported quantity recorded in this region exceeds that of most deserts worldwide. Notably, fine sand and total suspended particulates (TSP) contributed to approximately 90% of the sediment deposited on railway tracks and drawn in by passing trains. To control transportation of these fine particles, we propose increasing the height of sand‐blocking fences within the current railway wind‐blown sand protection system from 2 to 3 m. Simultaneously, anthropogenic damage to the Gobi surface should be minimized to reduce excessive dust release. This study provides insight into the wind‐blown sand movement mechanism over the Gobi surface under strong winds, and the eolian physics parameters revealed may serve as a theoretical foundation for preventing and managing eolian catastrophes along the Lanzhou–Xinjiang high‐speed railway.

Study and Analysis of RBFN based MPPT controller for wind energy integrated with Traction Power Supply System

The need of energy for railway is rising due to the increased speed at which trains must operate to maintain safety and dependability. This situation implies more electricity consumption and more challenges to railway operation stability. Therefore, this research suggests configuring wind energy integration with the current railway traction substations built on the current traction substation. The suggested setup consists of a converter that converts DC to DC with RBFN-based MPPT regulator wind energy source linked to a permanent magnet synchronous generator (PMSG), a rectifier, and a conventional traction system. The proposed system is modelled and analyzed by utilizing a radial basis function network (RBFN) in this study. Three traction substations: Aysha, Adegla and Dewanle:-are the subject of the case study, which integrates wind energy with the railway electric power system working at 25 kV AC. For the Aysha wind farm, a MATLAB/Simulink simulation is run in order to confirm the suggested technology. The setup with or without MPPT was used in order to evaluate the results. The proposed system produces an average output of 260.3kW without MPPT and 289.3kW with MPPT controller at wind speed of 20m/sec. The simulation findings suggest that the RBFN-based control method performs better under diverse wind conditions and is more suited for wind energy integration with traction system.

TRAM-TRAIN SYSTEM AS A POTENTIAL TRANSPORT SOLUTION FOR THE OLOMOUC REGION

The article is focused on the frequently discussed topic of suburban and regional railway system modernization comparing different approaches to consider by local authorities. To make a precedent and to better contribute to practical problems, a middle-sized city of Olomouc (Czechia) is chosen to demonstrate the upgraded regional transport system design with respect to the regional specifics and utilizing of the current railway and tramway infrastructure. With a new, innovative approach to the potential tram-train implementation in the Olomouc Region, the technical and operational features of the current tram-train systems and vehicles are analysed. By implementing the most suitable ones, the regional tram-train system proposal in the conditions of Olomouc may serve as a guide for similar planned systems in the countries with limited legislative and technical experience regarding the tram-train systems (especially in Central Europe), their suitability for the region, their design, and introduction. For the qualitative assessment of the different relevant approaches, a comparative analysis is used. As a result of the analysis, a tram-train system is recommended for the further transport planning stages as it significantly improves both urban and suburban public transport in the Olomouc Region by increasing their average speed and accessibility. For better financial and technical implementation, the project is divided into several stages. Unlike the already presented solutions, it combines shorter travel times of the regional rail and the populated area coverage reached by regional buses and serves as both an attractive and financially sane extension of a regional public transport system.

Deep Learning (Fast R-CNN)-Based Evaluation of Rail Surface Defects

In current railway rails, trains are propelled by the rolling contact between iron wheels and iron rails, and the high frequency of train repetition on rails results in a significant load exertion on a very small area where the wheel and rail come into contact. Furthermore, a contact stress beyond the allowable stress of the rail may lead to cracks due to plastic deformation. The railway rail, which is the primary contact surface between the wheel and the rail, is prone to rolling contact fatigue cracks. Therefore, a thorough inspection and diagnosis of the condition of the cracks is necessary to prevent fracture. The Detailed Guideline on the Performance Evaluation of Track Facilities in South Korea specifies the detailed requirements for the methods and procedures for conducting track performance evaluations. However, diagnosing rail surface damage and determining the severity solely rely on visual inspection, which depends on the qualitative evaluation and subjective judgment of the inspector. Against this backdrop, rail surface defect detection was investigated using Fast R-CNN in this study. To test the feasibility of the model, we constructed a dataset of rail surface defect images. Through field investigation, 1300 images of rail surface defects were obtained. Aged rails collected from the field were processed, and 1300 images of internal defects were generated through SEM testing; therefore, a total of 1300 pieces of learning data were constructed. The detection results indicated that the mean average precision was 94.9%. The Fast R-CNN exhibited high efficiency in detecting rail surface defects, and it demonstrated a superior recognition performance compared with other algorithms.

Location and segmentation of important railway signs based on improved segmentation

Purpose With the rapid development of railway-intelligent video technology, scene understanding is becoming more and more important. Semantic segmentation is a major part of scene understanding. There is an urgent need for an algorithm with high accuracy and real-time to meet the current railway requirements for railway identification. In response to this demand, this paper aims to explore a variety of models, accurately locate and segment important railway signs based on the improved SegNeXt algorithm, supplement the railway safety protection system and improve the intelligent level of railway safety protection. Design/methodology/approach This paper studies the performance of existing models on RailSem19 and explores the defects of each model through performance so as to further explore an algorithm model dedicated to railway semantic segmentation. In this paper, the authors explore the optimal solution of SegNeXt model for railway scenes and achieve the purpose of this paper by improving the encoder and decoder structure. Findings This paper proposes an improved SegNeXt algorithm: first, it explores the performance of various models on railways, studies the problems of semantic segmentation on railways and then analyzes the specific problems. On the basis of retaining the original excellent MSCAN encoder of SegNeXt, multiscale information fusion is used to further extract detailed features such as multihead attention and mask, solving the problem of inaccurate segmentation of current objects by the original SegNeXt algorithm. The improved algorithm is of great significance for the segmentation and recognition of railway signs. Research limitations/implications The model constructed in this paper has advantages in the feature segmentation of distant small objects, but it still has the problem of segmentation fracture for the railway, which is not completely segmented. In addition, in the throat area, due to the complexity of the railway, the segmentation results are not accurate. Social implications The identification and segmentation of railway signs based on the improved SegNeXt algorithm in this paper is of great significance for the understanding of existing railway scenes, which can greatly improve the classification and recognition ability of railway small object features and can greatly improve the degree of railway security. Originality/value This article introduces an enhanced version of the SegNeXt algorithm, which aims to improve the accuracy of semantic segmentation on railways. The study begins by investigating the performance of different models in railway scenarios and identifying the challenges associated with semantic segmentation on this particular domain. To address these challenges, the proposed approach builds upon the strong foundation of the original SegNeXt algorithm, leveraging techniques such as multi-scale information fusion, multi-head attention, and masking to extract finer details and enhance feature representation. By doing so, the improved algorithm effectively resolves the issue of inaccurate object segmentation encountered in the original SegNeXt algorithm. This advancement holds significant importance for the accurate recognition and segmentation of railway signage.

Прогнозирование влияния электромагнитного поля контактной сети модернизированного участка Октябрьской железной дороги на ВЛ высокого напряжения

The article is devoted to the issue of changing the intensity of the electromagnetic influence of the AC overhead contact system on the disconnected HV transmission line as a result of the modernization of the railway section. Calculation models of AC traction network and power transmission line are built in the ATP-EMTP program. The comparison of the results of calculations of the induced voltage on the disconnected transmission line caused by the influence of the AC overhead contact system of a single- and double-track sections of an АС current railway is carried out.

Снижение экономических потерь в контактной сети и воздушных линиях, электрифицированных на переменном токе

Purpose: To reduce economic losses in the contact network (CN) and overhead lines (OL) electrified with alternating current. The existing electromagnetic influences on the alternating current railway lead to significant economic losses. Additionally, there is a problem of the contact wire (CW) burnout during the passage of a neutral section with a raised pantograph under voltage on a high-speed railway line (HSRL). CW burnout leads to failure of the contact network, repair costs, possible damage to other people’s property and rolling stock. As a whole, all this represents significant economic losses. Methods: The analysis of material and time costs for the elimination of problems that arise due to the CW burnout or due to the use of manual labor during the installation of OL has been carried out, in comparison with the proposed solutions to reduce economic losses. Results: In solving the problem of the negative electromagnetic influence of the contact line (CL) on the OL, a mobile mechanized complex (MMC) is designed to help, which performs the transposition of the OL wires in 6 steps with scrolling by 60° each support. This method will allow us to place the OL wires equidistantly from the contact wire. Scrolling with once-per-support frequency will align the asymmetry of the linear electrical parameters. All in all, MMC performs installation in an automated mode. The problems of the CW burnout can be reduced by the insulating coupling device (ICD) of the CL. ICD CL is a set of step resistances, which are located at the outer sections of the phase wires before and after the neutral section. It is aimed at reducing the current to a safe value, which will not lead to the contact wire burnout, failure of the CN and/or rolling stock and possible damage to other people’s property. Practical significance: The result is a set of measures in the form of MMC to reduce economic losses in overhead lines from the influence of CN and ICD CL to reduce losses in the contact network by maintaining the operability of the contact wire.

Silicate and Portland cement based compositions for protection against electrical corrosion

AbstractConductive silicate compositions and compositions based on Portland cement for screen protection against electrical corrosion of reinforced concrete structures and buildings on electrified direct current railways are theoretically and experimentally substantiated. The compositions are used as putty or plaster on structures to be protected. The resulting coating drains corrosive leakage currents from the rails through grounding. In these compositions, the component that provides electrical conductivity is dispersed graphite. Depending on the additional requirements for the coating, sodium silicate with sodium silicon fluoride or Portland cement are used as binders. It was established that in these compositions the silicate and cement components are conductors of the second kind, and graphite is the conductor of the first kind. Due to the imposition of an electric potential, the surfaces of dispersed graphite particles are divided into cathodic areas and anodic areas, where the graphite dissolves, therefore the resource of the composition is determined by the amount of electricity passed through. In addition, it was found that the electrophysical properties of the compositions are in antagonism with their rheological, physical‐mechanical, hydro physical properties, therefore, the development of their composition should be carried out by methods of compromise optimization. Formulations of compositions that have been tested in operational conditions have been developed.

Popularization of high-speed railway reduces the infection risk via close contact route during journey

The risk of COVID-19 infection has increased due to the prolonged duration of travel and frequent close interactions due to popularization of railway transportations. This study utilized depth detection devices to analyze the close contact behaviors of passengers in high-speed train (HST), traditional trains (TT), waiting area in waiting room (WWR), and ticket check area in waiting room (CWR). A multi-route COVID-19 transmission model was developed to assess the risk of virus exposure in these scenarios under various non-pharmaceutical interventions. A total of 163,740 s of data was collected. The close contact ratios in HST, TT, WWR, and CWR was 5.8%, 64.0%, 7.7%, and 49.0%, respectively. The average interpersonal distance between passengers was 0.85 m, 0.92 m, 1.25 m, and 0.88 m, respectively. The probability of face-to-face contact was 9.5%, 70.0%, 64.2%, and 5.8% across each environment, respectively. When all passengers wore N95 respirators and surgical masks, the personal virus exposure via close contact can be reduced by 94.1% and 51.9%, respectively. The virus exposure in TT is about dozens of times of it in HST. In China, if all current railway traffic was replaced by HST, the total virus exposure of passengers can be reduced by roughly 50%.

Overview of Stability and Coordination Control for MVDC Traction Power Supply System

The traditional 25KV electric railways have various problems such as power quality issues, passing neutral sections, complex storage, and utilization of regenerative braking energy, the medium‐voltage direct current (MVDC) traction power supply system (TPSS) may be a potential alternative electric railway mode and can be freely accessed to the renewable energy and energy storage systems, which is an important development direction of the future low‐carbon RES. This paper first describes the structure and characteristics of the current Railway Electrification System (RES), and then analyzes and summarizes the current research status of the MVDC TPSS topology structure, modeling method, stability criterion, and analysis method and coordination control strategy. Finally, combined with the research status, the development direction of the MVDC TPSS has prospected. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Methodology for assessing the impact of regenerative braking energy injection of a direct current railway system on the distribution grid

Methodology for assessing the impact of regenerative braking energy injection of a direct current railway system on the distribution grid

Artificial neural network-based investigation on high-speed train-induced embankment vibration in frozen regions

High-speed trains (HSTs) induce vibrations that deteriorate the embankments of ballastless tracks, particularly in frozen regions, necessitating vibration assessments for existing high-speed railways (HSRs). This study developed an indirect thermal-dynamic coupled two-dimensional (2D) finite element (FE) model to investigate the dynamic responses of the embankment of ballastless tracks to various subgrades and subsoils, train speeds, and frost depths in frozen regions. The results indicate that subgrade is the key parameter to analysing the dynamic response of the train–track–ground system considering train speeds. A fast and high-accuracy prediction method for the vibration responses was developed using an artificial neural network (ANN) and used to predict the vibration level under different conditions. Prediction results determined train speeds under 400 km/h safe for HSRs. This study can improve knowledge of ballastless track substructure design and extend the applicability of the current railway code to higher train speed conditions in frozen regions.

DEVELOPMENT OF IDEAS ABOUT ELECTRICAL CORROSION OF RAILWAY TRACK STRUCTURES AND IMPROVEMENT OF THEIR PROTECTION METHODS USING ELECTRICALLY CONDUCTIVE COMPOSITIONS

Research is devoted to the development of ideas about the mechanism of the flow of corrosion currents through the structures of railway tracks and buildings and the justification of methods of their protection against electrical corrosion. As a result of theoretical studies and field tests, the electric circuits of the leakage currents from the pulsating unidirectional electric potential of the POEP, which arise during the passage of the electric rolling stock along the electrified direct current railway tracks, have been clarified. Current carriers are installed in the elements and structures of the track and buildings. In concrete, soil, which are conductors of the second kind, these carriers are mainly cations Ca2+, Na+, anions OH-. It was found that in reinforced concrete sleepers, supports of passenger platforms due to the influence of POEP, zones of neutralization and leaching of concrete, cathode and anode zones of steel reinforcement are formed. Corresponding chemical and electrochemical reactions of leaching and carbonization of lime, oxidation of iron, etc. occur in these zones. It is proposed to prevent corrosion processes in these zones by diverting currents with grounded screens-coatings made of electrically conductive compositions based on mineral binders -Portland cement with a complex chemical additive or sodium silicate and a filler - dispersed graphite. The proposed indicator of the effectiveness of these screens-coatings, which is the degree of reduction of the current strength through the structure. As a result of experimental studies, it was established that it depends on the share of the contact area of the steel grounding device with the screen from the area of the screen itself, and the corresponding dependencies were obtained. New methods of protecting track structures and structures from electrical corrosion are substantiated, and appropriate structural and technological solutions are developed.

Application of the Method of Increasing the Practical Throughput Performance in the Conditions of the Slovak Railways

Abstract Rail transport is a continuous process that must be coordinated at all levels of management and is determined by technological processes. From a technological point of view, it is important to correctly determine the practical throughput of the track section, also called the railway infrastructure capacity. This means how much train traffic can be used to load the track section so that it shows sufficient train traffic stability even in the event of operational irregularities. The article is focused on the method of increasing the capacity of the Drienovská Nová Ves - Kysak track section with using the application of the method of determining the practical throughput performance in the anticipated timetable. Detailed determination of the occupation times of the section in the current state and in the application of individual proposals to increase the capacity of the investigated railway line provide us with information on other possibilities of modernization of the railway infrastructure in Slovak Republic. The article describes and evaluates the advantages and disadvantages of individual proposals to increase capacity of the track section. As part of the future modernization of the railway infrastructure of this track section, it is necessary to implement these measures, as the track section under investigation is part of the AGTC and TEN-T international railway corridors. When designing new corridors, it is necessary to analyse and optimize the current railway network. The intention is not only to increase the quality of railway infrastructure, but also the quality of goods and passenger transport.

Balancing the Active Power of a Railway Traction Power Substation with an sp-RPC

The railway system is one of the safest, most efficient, and environmentally friendly means of land transport for people and goods. However, as the demand for mobility has increased, the current railway system has shown some weaknesses, requiring an increase in catenary power in order to be able to supply power to longer trains and faster locomotives, as well as to increase rail traffic. This paper proposes a control algorithm to be implemented in a sectioning post-Rail Power Conditioner (sp-RPC). The sp-RPC is connected to the neutral section between two traction power substations (TPS). With the control algorithm, it is possible to minimize the existing unbalance of the active powers of each TPS. In a regenerative braking condition, this surplus energy can be used to assist the traction of another locomotive on the existing overhead line. In this way, it is possible to increase the capacity of the overhead line. The analysis was performed with computer models using a modular multilevel converter (MMC) topology for the sp-RPC. Quantitative results for different consumption events of the locomotives and the analysis of the response to these variations are presented.

Theoretical and Experimental Investigation on the Flexural Behaviour of Prestressed NC-UHPC Composite Beams.

To investigate the normal section strength and cracking bending moment of normal concrete-ultra-high-performance concrete (NC-UHPC) composite beams, calculation formulas were established considering the tensile strength of UHPC based on the current railway bridge design code. Using the railway T-beam as a template, prestressed NC-UHPC composite beams with different NC layer heights were built. A static bending test was performed, the pressure of the steel strand and the deflection and strain of the beam were measured, and the evolution of cracks in each beam was observed. The calculation formulas of the normal section strength and cracking bending moment of NC-UHPC composite beam were verified by the test. The results showed that the type of strain was similar to load-deflection curves with increasing load; the bending failure process of the NC-UHPC composite beam showed four obvious stages: elasticity, uniform cracking, crack development, and yield. Cracks in the beam started to appear at stage II, developed rapidly at stage III, and stopped emerging at stage IV. The calculation formulas for the normal section strength and the cracking bending moment of the NC-UHPC composite beam were in good agreement with the test values. Normal concrete with a compressive strength of 80 MPa can replace UHPC for the design of NC-UHPC composite beams.

Impact of Superconducting Cables on a DC Railway Network

The Société Nationale des Chemins de fer Français (SNCF) is facing a significant challenge to meet the growth in rail traffic while maintaining continuous service, particularly in densely populated areas such as Paris. To tackle this challenge, the SNCF has implemented several electrification projects. These projects aim to reduce line losses and decrease voltage drops on the railway network. Amongst the possible technological choices, high temperature superconductor (HTS) cables have been evaluated, since they offer greater energy density at lower electrical losses than conventional cables. This feature is advantageous in order to transmit more electrical energy at a lesser footprint than conventional cable, therefore avoiding costly modifications of the existing infrastructures. In the present work, the electromagnetic response of two HTS cables topologies, unipolar and bipolar, was analyzed, and their impact on a direct current (DC) railway network under load was assessed. A commercial finite element (FE) software, COMSOL Multiphysics, was used to carry out a detailed FE model that accounts for the non-linearity of the electrical resistivity ρ (J, B, θ) of the superconducting cable. This FE model was coupled with a lumped-parameter circuit model of the railway network, which is particularly suited for transient simulations considering train motion. Based on a case study representing a portion of the Parisian railway network, it was found that the insertion of a superconducting cable can result in a reduction of electrical losses by 60% compared to conventional cable as well as an 8.6% reduction in the total electrical consumption of the traction network.