Overhead Contact System Research Articles

Optical Measurement System for Monitoring Railway Infrastructure—A Review

Rail infrastructure plays an important role in fulfilling the demand for freight and passenger transportation. Increases in traffic volume, heavier axles and vehicles, higher speeds, and increasing climate extremes all contribute to the constant strain on the infrastructure. Due to their major importance in the transportation of people and freight, they are subject to continuous condition monitoring. This is an essential requirement for the selective planning of maintenance tasks and ultimately for safe and reliable operation. Various measuring systems have been developed for this purpose. These must measure precisely, quickly, and robustly under difficult conditions. Whether installed from mobile or stationary platforms, they have to cope with a wide range of ambient temperatures and lighting conditions, harsh environmental influences, and varying degrees of reflection. Despite these circumstances, railway operators require precise measurement data, high data densities even at high traveling speeds, and a user-friendly presentation of the results. Photogrammetry, laser scanning, and fiber optics are light-based measurement methods that are used in this sector. They are able to record with high precision rail infrastructure such as overhead contact systems, clearance profiles, rail tracks, and much more. This article provides an overview of the established and modern optical sensing methods, as well as the use of artificial intelligence as an evaluation method, and highlights their advantages and disadvantages.

Ice-Covered Environmental Adaptability Assessment for Overhead Contact System in High-Speed Railways

Ice-Covered Environmental Adaptability Assessment for Overhead Contact System in High-Speed Railways

Design exploration of the status detection system for car-mounted catenary tension compensation device

The tension compensation device is a critical component for maintaining constant parameters of the contact wire, such as tension, catenary height, and sag, in the overhead contact system. Its operational status directly affects the normal operation of the entire contact wire system. This paper provides a comprehensive review of existing tension compensation device state detection techniques and analyzes their shortcomings. By comparing with existing methods for monitoring cable tension, a vehicle-mounted contact wire tension compensation device state detection system based on the three-point bending method is proposed. This system can simultaneously monitor the operational status of the device at the line side and anchor section, issuing real-time warnings in case of abnormal device states and possessing significant application value. This study provides a reliable tool for railway operators to monitor the devices status and take timely maintenance and adjustment measures to ensure the normal operation of the contact wire system

Dynamic Response Study of Overhead Contact System Portal Structure Based on Vehicle–Track–Bridge Coupled Vibration

In light of the rapid development of electrified railways, the safety and stability of train operations, as well as the catenary’s interaction with current quality, have garnered widespread attention. Electrified train operation with additional track irregularities serves as a principal excitation source within the vehicle–bridge–catenary system, significantly influencing the vibration characteristics of the system. Addressing the aforementioned issues, we first established the vehicle–track dynamics model and the bridge–catenary finite element model based on the principles of coupled dynamics of the vehicle–track system. These models are interconnected using dynamic forces between the wheel and rail. Subsequently, within the vehicle–track coupled system, track random irregularities are introduced as input excitations for the coupled model, and the dynamic response of the system is simulated and solved. Then, the obtained wheel–rail forces are applied to the bridge–catenary coupled system finite element model in the form of time-varying moving load forces. Finally, the dynamic response characteristics of the catenary portal structure under different conditions are determined. Meanwhile, a study on the vibration characteristics of the truss-type pillar portal structure was conducted, and the results were compared with those of existing models. The results indicate that the vertical and lateral forces between the vehicle and track are positively correlated with the speed and irregularity amplitude. Response values such as the derailment coefficient and wheel load reduction rate are within the specified range of relevant standards. The low-order natural resonant frequency of the truss-type pillar structure has, on average, increased by 0.86 compared to the existing pillar structure, which signifies improved stability. Furthermore, under various conditions, the average reductions in maximum displacement and stress response of this pillar structure are 13.2% and 14.19%, respectively, in comparison to the existing pillar structure, rendering it more suitable for practical engineering applications.

A fast solution method for the interaction between the rigid overhead contact system and pantograph on long railway lines

Currently, simulation is an important method for studying the interaction between the pantograph and the rigid overhead contact system (ROCS). However, when solving the ROCS model for long railway line scenarios, the problem of intractable or inefficient computation arises due to the excessively large size of the matrix. To address this issue, this paper proposes a method called: a fast solution method for the interaction between the rigid overhead contact system and pantograph on long railway lines based on a coupled window approach (hereinafter referred to as: CW-RCP). The CW-RCP method utilises coupled windows to simulate the ROCS model, effectively limiting the length of the ROCS involved in each computation. This approach greatly enhances computational efficiency. After deriving the dynamic equations and solving equations of the CW-RCP method in detail, the effectiveness, advantages, and applications of this method are discussed. The results demonstrate that the CW-RCP method can effectively compensate for the computational inefficiencies of traditional methods without compromising computational accuracy.

Influence of High-Speed Railway Subgrade Form on the Aerodynamic Characteristics of the Overhead Contact System Positive Feeder in the Gale Area

Influence of High-Speed Railway Subgrade Form on the Aerodynamic Characteristics of the Overhead Contact System Positive Feeder in the Gale Area

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.

Modeling of modes of traction power supply systems equipped with renewable energy sources

The article presents the results of research aimed at developing digital models for power flow analysis of railway power supply systems (RPSS) equipped with distributed generation (DG) units based on renewable energy sources. We employed the technique of modeling in the phase reference frame, which has the following features: system-wide consistency, which enables modeling power flows in a way that takes into account the properties and characteristics of a complex RPSS and the feeding power system; versatility, which allows for modeling of traction networks of various designs; comprehensiveness, which consists in the possibility of power flow analysis of normal, emergency, and special states of a RPSS, such as those occurring during de-icing of overhead contact system wires. Three groups of models have been developed. The first one was designed for power flow analysis RPSSs with DG units based on synchronous generators driven by mini-HPP turbines. It is also possible to apply this model in the case of inverter generation that uses photovoltaic panels. The second group of models provided simulation of RPSS power flows with induction generators. The third group enabled power flow analysis in the case where there are three-phase generators connected to a single-phase traction network by means of Steinmetz converters. Active harmonic conditioners and controlled reactive power sources were used to reduce the negative impact of inferior power quality on voltage deviations and harmonic distortion. Simulation results produced by the software package Fazonord showed that the following positive effects can be obtained on the basis of the use of RES-based DG units: reduced costs of power supply; reduced imbalance on the buses of district windings of traction substations, stabilization of voltage levels on bow collectors of electric locomotives.

Point cloud segmentation of overhead contact systems with deep learning in high-speed rails

High-speed rails have strategic significance for political and economic development. As a critical part of the power supply system, overhead catenary systems (OCSs) power high-speed rails. OCSs are easily damaged due to artificial and natural factors. To ensure that OCSs work properly, researchers often use light detection and ranging (LiDAR) to recognize and inspect OCS components. However, recent OCS recognition methods relying on LiDAR need to enhance the ability to extract local features, integrate contextual features, and enhance crucial features while maintaining less latency and model complexity. To accomplish this objective, we proposed an accelerated point cloud segmentation algorithm for OCS recognition. The algorithm extracted local point cloud features based on machine learning methods. Then, it integrated the contextual features of point clouds using dot and accumulation operations. Additionally, we captured vital features and neglected unimportant features by constructing a feature enhancement algorithm. We accelerated the proposed algorithms by eliminating the run-time overhead of GPU scheduling. Experiments showed that our method had high precision with low model complexity and latency. For example, our precision was at least 0.64% better than comparison studies in recognizing steady arms. Our parameters were at least 43.59% fewer than others. Our optimized algorithm achieved a 2.47, 2.81, 3.24, 1.54, 7.12, and 7× speedup on the Nano, Tesla T4, RTX 2080 Ti, TX2, Tesla V100S GPU, and TITAN V, respectively. Our visualization effect also outperformed other methods in OCS recognition of high-speed rail scenarios.

Comparison of the Flywheel Energy Storage Performance in the Tram Overhead Contact System in the Cold and Warm Transport Operation Seasons

The article discusses the results of statistical and field studies of the energy consumption modes by the traction and non-traction loads in the overhead contact system (OCS) of the on-ground urban electric transport vehicles in the warm and hot seasons and the associated changes in the operation modes of an NKE-3GT stationary buffer energy storage. It is shown that the reduction of non-traction load, which takes place mainly in the warm season, entails a redistribution in the amounts of surplus and useful energy of electric rolling stock regenerative braking toward surplus energy and, hence, a growth in the surplus regeneration energy flows through the buffer energy storage.

Edge Intelligence-Based OCS Fault Detection in Rail Transit Systems

The Overhead Contact System (OCS) is critical infrastructure for train power supply in rail transit systems. OCS state monitoring and fault detection are indispensable to guarantee the safety of railway operations. The existing human-based OCS state monitoring and fault diagnosing method has some inherent drawbacks, such as poor real-time capability, low detecting precision, and waste of human resources. Edge Intelligence (EI) can perform complex computing tasks offloaded from trains within a little delay, and it is believed to help empower the OCS. In this paper, we propose an EI-based OCS state monitoring and fault detecting system. The latest Computer Vision (CV) model YOLOv5s is used to detect the OCS faults using the collected images. Edge Computing (EC) is used to perform the CV model inference. The EC system receives the OCS images taken by the train cameras and calculates the real-time fault detection results. The consistency and scalability of running jobs on edge devices are also addressed in our approach. Extensive experimental results demonstrate that the proposed EI-based system can detect OCS faults in real-time. The adopted YOLOv5s achieves a high fault detection rate, outperforming other models.

Modeling Power Flows and Electromagnetic Fields Induced by Compact Overhead Lines Feeding Traction Substations of Mainline Railroads

The ongoing re-equipment of electric power systems is based on the use of smart grid technologies. Among the key tasks that are solved on this basis are increasing the capacity of power transmission lines, reducing losses, and improving power quality. To address these issues, one can use compact power transmission lines. Such lines are notable for their complex split-phase designs and close together placement of current-conducting parts, so as to keep the distance to a permissible minimum, which is achieved by the use of insulating spacers. This article reports the results of computer-aided simulations performed for a standard railroad power supply system, the traction substations of which were connected to 220 kV networks through compact overhead lines (COHLs). The purpose of the study was to calculate the values of quantitative metrics that measure power quality and energy efficiency as well as electromagnetic safety. Modeling was performed in the three-phase reference frame with the use of techniques and algorithms implemented in the Fazonord software package. We considered a power supply system with 25 kV overhead contact systems. It was assumed that the external network used three different designs of COHLs: with coaxial, linear, and sector-shaped arrangements of conductors. Based on the results obtained, we concluded that (1) when using COHLs, the voltages on bow collectors of electric rolling stock were stabilized and did not exceed permissible limits; (2) losses in the traction network were reduced; and (3) the parameters of power quality and electromagnetic safety conditions in external power supply systems of railroads were improved, if judged in terms of electric and magnetic field strengths. Out of the eight types of COHLs considered, compact lines with the three-segment and concentric arrangement of conductors had the best performance, and the use of COHLs with the vertical arrangement of conductors made it possible to reduce electric field strengths. However, the designs of such transmission lines are quite complex and entail higher construction costs.

An automatic text generation algorithm of technical disclosure for catenary construction based on knowledge element model

Preparing technical disclosure documents has always been a labor-intensive task in the site management practice of current OCS (Overhead Contact System) project construction, and the overall information level of construction management is not high. As a result, the technical disclosure documents are of poor quality, which significantly affects the effective play of technical documents in guiding construction activities. In view of the above limitations, this paper proposes a text-generation method for OCS engineering technical disclosure based on a knowledge element model. By investigating the characteristics of OCS engineering technical knowledge, a representation model is established to model the technical knowledge from multiple sources, such as case data, standard specifications, and design data. As OCS engineering is highly standardized, we propose a case-rule hybrid reasoning model for the reuse of OCS engineering case knowledge. The mining and utilization of earlier engineering technical knowledge are made possible by similar retrieval of precedent situations and adaptive rules modification. Finally, we suggest an automatic text-generating technique based on a configuration template for new building projects. The knowledge element model is converted into a technical disclosure document expressed in natural language using a two-level mapping process. The cantilever installation project is used as an illustration for empirical research, and relevant practitioners are invited to carry out a manual review by questionnaire from the perspectives of topic relevance, topic integrity, topic word implication, sentence smoothness, sentence continuity, and information volume. At the same time, standard assessment metrics such as BLEU and ROUGE are employed to compare with the neural network-based text generation approach. The outcomes demonstrate that the strategy suggested in this paper can generate technical disclosure text that performs well. Overall, its text integrity and readability may satisfy on-site management's demands and help on-site management lessen the workload of technical management staff.

Effect of Ambient Temperature on Current Collection Quality in Pantograph–Catenary Interaction

This paper investigates the effect of the ambient temperature change on the dynamic interaction between pantograph and catenary (PAC). Thermal expansion/contraction of the components of the overhead contact system (OCS) is considered. Simulation results show that the thermal stress has a much greater influence on the longitudinal positioning of the contact wire than on the horizontal and vertical positioning. When ambient temperature reduces to [Formula: see text] from design temperature of [Formula: see text]C, the maximum longitudinal displacement of the positioner can reach as high as 301 mm, while the maximum horizontal and vertical displacement of the positioner is within 4[Formula: see text]mm. The change of ambient temperature results in the uneven tension distribution of the contact wire, especially near the central anchor. With the increase in temperature, the tension of contact wire decreases; vice versa, with the decrease in temperature, the tension of contact wire increases. For nine-span OCS, the tension change caused by ambient temperature change shall not exceed 2%. The variation of ambient temperature also leads to the deterioration of current collection quality. It is shown that a decreasing ambient temperature results in more significant changes in contact force, close to 5%. An increasing ambient temperature environment leads to a higher uplift of pantograph, close to 30%.

Calculation method and model tests of pile frost jacking for railway overhead contact systems in permafrost regions

One of the major challenges encountered in electrification reconstruction project of Golmud-Lhasa section of Qinghai-Tibet railway of China is ensuring the frost jacking stability of the pile foundation of overhead contact system mast (OCSM). To evaluate the resisting frost jacking performance of OCSM pile in permafrost regions, a theoretical model of OCSM pile in permafrost soils under the effect of frost heave was constructed based on superposition principle and deformation coordination relationship between the pile and soil. The model was solved by using the finite difference method combined with MATLAB. Then, large scale model tests were performed to investigate the thermodynamic behaviors of OCSM piles with different sections (equal section circular pile, straight cone cylindrical pile and curved cone cylindrical pile) in the permafrost soils under freeze-thaw actions, after which the theoretical model were validated. It was found that distribution curves of pile axial force obtained by the calculation method is basically consistent with model test results in the overall trend, implying that the calculation model is reasonable and feasible. During soil freezing, the pile is under tension as a whole, and the axial force is greatest near the depth of frost penetration. The maximum value of tangential frost-heave stress occurs near the ground surface. The total tangential frost heaving force of the curved cone cylindrical pile is the smallest, and the effect of resisting frost jacking is the best. These research results can provide a reference for resisting frost jacking design of OCSM pile in permafrost regions.

An improvement of manufacturing process using 3D printing technology for overhead line components on railway electrification

In an electric railway, an overhead contact system (OCS) is assembled with many components, and it maintains a voltage of 25 kV to supply electricity to the electric trains. As electric trains grow faster, the overhead line comes to employ a diverse range of materials to deliver electricity and maintain high tension. Overhead lines supply electricity to electric trains through mechanical contact with a pantograph, and since they are not fault-tolerant, they require high reliability. That makes it take a long time to develop and supply components and also makes it difficult and time consuming to apply new materials or new designs to components. This study proposes a manufacturing process for overhead line components using 3D printing technology. For this, a clevis terminal clamp for high-speed railway was chosen and a design drawing was created with 3D scanning. For molding, additive manufacturing technology was used. The study castings were obtained by applying precision casting and sand mold casting methods, respectively, and their elongation and tensile strength were compared with products made with a traditional method.

<b>Exposition of Revision of Seismic Design Guideline for Overhead Contact Systems</b>

In Japan, in order to prevent supports (referred to poles and portal structure etc.) in overhead contact systems from collapsing at the time of an earthquake, we design them according to the Seismic Design Guideline for Overhead Contact Systems and Commentary (hereafter referred to as the OCS Guideline). We revised the OCS Guideline in 2013 to evaluate seismic performance of supports more precisely. The paper shows the process of revising OCS Guideline until now and details of the latest revision of the OCS Guideline.

Fault detection of overhead contact systems based on multi-view Faster R-CNN

Overhead contact systems are important power supply equipments for electrified railway locomotives. If there are faults in the equipment, it will threaten the safety of train operation. Dropper faults and foreign matter are two common types of Overhead contact systems faults, the fault regions of which occupy a relatively small area in the whole image, so it is difficult to detect the faults accurately by capturing detailed features using original Faster R-CNN. To solve the above problem, an improved Faster R-CNN based on convolutional neural networks, named multi-view Faster R-CNN, is proposed in order to extract more details of the fault regions by combining deep and shallow feature maps. Experiments on the images collected from the Lanzhou-Xinjiang Railway line show that the feature fusion can significantly enhance the mean average precision. The precision of our model on the test set was 89.53%, increasing by 3.5%, 9.65%, and 5.8% compared with YOLOv3, SSD, and Faster R-CNN, and the detection accuracies of our model for unforced droppers and foreign matter were 88.17% and 90.60%, respectively, under a recall rate of almost 1.0. Because the multi-view feature fusion model in our method can flexibly detect faults with various sizes, it has an important application value in the fault detection of an overhead contact system.

Research on Key Technology of Anti-ice Melting for Overhead Contact System of Shuohuang Railway

Research on Key Technology of Anti-ice Melting for Overhead Contact System of Shuohuang Railway

Automation of the Process of Measurement of Electrical Parameters in Microprocessor Devices of Relay Protection

The article continues a complex research of the operation of standard microprocessor protection of feeders of the AC overhead contact system DPA-27.5-TNF operated at the Zabaikal’skaya railway in regards to the possibility of obtaining the array of information in the online mode on the magnitudes of start-up and transient currents that flow in the traction network in different recurring modifications of the train schedule (TS). In the future, it would reduce the number of relay protection tripping events due to undetermined causes, thereby increasing its selectivity.