Electric Railway Systems Research Articles

A Review on Single Phase AC System of Railway Electrification

The widespread adoption of 25 kV, 50 Hz single-phase AC supply in long-distance electrified railway systems poses significant challenges to power quality in transmission networks. This paper presents an in-depth investigation into the influence of electric railway systems on a 110 kV transmission system, with a specific focus on locomotives equipped with diode rectifiers. Harmonic currents generated by these locomotives and unbalanced voltages introduced by single-phase traction loads are known to adversely affect power system components, leading to issues such as overheating, additional losses, and interference with communication systems. The focus of this paper is not only to understand the fundamental principles but to conduct a deep exploration of the functioning of various components such as locomotives, contact lines, and substations. High voltage This voltage is supplied from the substation or directly from the generating station. This high AC voltage (25KV) is first transformed into low AC voltage (415V). Three-phase induction motors are used because they provide high torque, are reliable, and are more efficient. The AC voltage in the second phase is rectified to DC and then converted into a phase AC using VFD. The VFD provides variable frequency and voltage to run the induction motor at different speeds.

Modelling a DC Electric Railway System and Determining the Optimal Location of Wayside Energy Storage Systems for Enhancing Energy Efficiency and Energy Management

Global demand for fossil fuels is highly increasing, necessitating energy efficiency to be enhanced in transitioning to low-carbon energy systems. Electric railways are highly efficient in reducing the transportation demand for fossil fuels as they are lightweight and their energy demand can be fed by renewable energy resources. Further, the regenerative braking energy of decelerating trains can be fed to accelerating trains and stored in onboard energy storage systems (ESSs) and stationary ESSs. It is fundamental to model electric railways accurately before investigating approaches to enhancing their energy efficiency. However, electric railways are challenging to model as they are nonlinear, resulting from the rectifier substations, overvoltage protection circuits, and the unpredictability and uncertainty of the load according to the train position. There have been few studies that have examined the ESS location’s impact on improving the energy efficiency of electric railways while using specialised simulation tools in electric railways. However, no single study exists that has studied the location impact of stationary ESSs on the energy efficiency of electric railways while the trains are supported by onboard ESSs. Given these goals and challenges, the main objective of this work is to develop a model using commercial software used by industry practitioners. Further, the energy saving is aimed to be maximised using stationary ESSs installed in optimal locations while trains are supported by onboard ESSs. The model includes trains, onboard ESSs, rail tracks, passenger stations, stationary ESSs, and traction power systems involving power lines, connectors, switches, sectioning, and isolators. In this article, a test scenario is presented comprising two trains running on a 20 km with three passenger stations and two substations. The trains and track are modelled in OpenTrack simulation software (Version 1.9) while the power system is modelled in OpenPowerNet simulation software (Version 1.11). The two simulation tools are used in the railway industry and can produce realistic results by taking into account the entire electrical network structure. A stationary ESS is added on the wayside and moved in steps of 1 km to obtain the optimal location before investigating the impact of stationary ESSs on the performance and energy management of onboard ESSs. It is found that the energy saving when installing a stationary ESS at the optimal location is 56.05%, the peak-power reduction of Substation 1 is 4.37%, and the peak-power reduction of Substation 2 is 18.67%.

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.

Revolutionary Design and Optimization of Railway Electrification Overhead Equipment in High-Altitude Tunnels: A Case Study of the Magnificent T-80 Tunnel

Railway electrification systems are critical for modernizing railway infrastructure, enhancing efficiency, and reducing environmental impact to obtain zero emissions targets. In high-altitude regions, such as mountainous terrains, unique challenges arise due to extreme weather conditions, terrain complexities, and operational requirements. This case study focuses on the innovative and optimized design of overhead equipment (OHE) for railway electrification in high-altitude tunnels, presenting a comprehensive analysis of the planning, design, and implementation process for 25kV AC Overhead equipment. The study begins with an overview of significant considerations in designing 25kV AC OHE systems for high-altitude tunnels, including altitude effects on electrical performance, weather effects, structural safety checks, fire scenarios, vibration effects, and tunnel bolt drilling for OHE equipment installation. It also covers aspects such as the selection of auto tensioning devices, electrical clearances, and earthing & bonding according to railway/EN/IEC standards. Also, the paper examines the monetary feasibility and environmental sustainability of the proposed OHE design, emphasizing the importance of life-cycle cost analysis and environmental impact valuation. It underscores the significance of adopting a holistic approach that balances technical requirements, operational efficiency, and environmental stewardship in railway electrification projects.

An Energy Management Method for Magnetic Field Energy Harvesters Under Wide-Range Current in Railway Electrification Systems

The wide-range traction current brings great challenges to the stable operation of the magnetic field energy harvester (MFEH). Specifically, when the traction current is large, the core saturation increases, resulting in violent vibrating of the magnetic core. When the traction current is low, the energy harvested by the MFEH is insufficient to power the load. To address these vital problems, an energy management method for MFEH is proposed to track the critical saturation point, i.e., the maximum power point in the unsaturated region. In this method, by regulating the equivalent load, the core voltage is controlled at the critical saturation voltage under different current levels. Moreover, the supercapacitor is employed to store excess energy at large currents, and the stored energy is released at low currents. Furthermore, a design procedure for the core and winding is proposed in this work, which can be used to adjust the critical saturation voltage of the MFEH. A laboratory prototype is built to verify the effectiveness of the proposal. The results show that the MFEH can operate at the critical saturation point and provide stable energy for the load under different current levels. This means that saturation suppression, maximum power point tracking, and energy management can be realized by applying the proposed method.

Smart AC-DC Coupled Hybrid Railway Microgrids Integrated with Renewable Energy Sources: Current and Next Generation Architectures

In recent years, there has been increasing interest in integrating the smart grid concept into railway networks, which has been driven by the need to enhance energy efficiency and reduce air pollution in such energy-intensive systems. Consequently, experts have actively sought innovative solutions with which to tackle these challenges. One promising strategy involves integrating renewable energy sources (RESs), energy storage systems (ESSs), and electric vehicle charging stations (EVCSs) into current electric railway systems (ERSs). This study begins by examining the concept of implementing smart grids in railway systems through bibliometric analysis. It then delves into the realization of a hybrid railway microgrid (H-RMG) designed to enhance power flow capacities, improve energy efficiency, and address power quality issues in traditional AC railway networks. This paper introduces various future AC–DC-coupled hybrid railway microgrid (ADH-RMG) architectures centered around a shared DC bus acting as a DC hub for upgrading conventional AC railway systems utilizing interfacing static converters. Through an exploration of different possible ADH-RMG configurations, this research aims to offer valuable insights and a roadmap for the modernization and reconstruction of existing railway networks using smart grid technologies. The integration of RESs and EV charging infrastructures within the ADH-RMG concept presents a promising pathway toward establishing more sustainable and environmentally friendly railway systems.

An adaptive controller for power quality control in high speed railway with electric locomotives with asynchronous traction motors

Introduction. Power quality in an electric railway system pertains to the dependability, consistency, and purity of the electrical power provided to different components and systems within the railway infrastructure. Assessing power quality offers considerable opportunities to improve the efficiency of railway systems. Problem. Managing the flow of active and reactive power effectively, decreasing harmonic currents, and addressing the negative sequence component are all critical parts of improving power quality for electrified rail systems. As a result, flexible AC transmission systems are the major means of minimizing or decreasing these difficulties. Purpose. This study describes a half-bridge reactive power railway power conditioner (HB-RPC) with a novel Ynev balancing transformer. HB-RPC is made up of four switching devices and two DC capacitors and the compensator’s stability is determined by the operating voltage of the DC-link. Any variations or imbalances in the DC voltage might cause the compensator to operate in an unstable manner. Novelty. Of a novel balanced transformer with HB-RPC in a high-speed railway system with two scenarios. Methods. The study utilized MATLAB/Simulink software for simulation purposes. The system integrates a fuzzy logic controller (FLC) and a PI controller to optimize DC voltage, ensuring its constancy and balance, with the objective of improving the overall stability of the system. Results. The simulation outcomes illustrate the efficacy of the control approach. Through a comparison of results between scenarios (two and four trains) with the PI-based-HB-RPC and the FLC-based-HB-RPC, the system exhibits enhanced stability for the proposed railway system when employing the FLC-based-HB-RPC, compared to a controller based on PI. Practical value. The proposed configuration elucidates its role in enhancing both the dynamic performance of the system and the power quality of the three-phase rail traction chain.

Electrifying Innovation: The Transformative Impact of Power Electronics in Modern Infrastructure

This article delves into the transformative role of electric power electronics in shaping modern infrastructure across diverse domains. It comprehensively explores the applications of these technologies in energy distribution, transportation infrastructure, and communication networks. The discussion begins with how power electronics enable the integration of renewable energy sources into smart grids, enhance the efficiency of high-voltage direct current (HVDC) systems, and facilitate advanced energy storage solutions. In transportation, the focus shifts to electric vehicles, railway systems, and intelligent transportation systems, highlighting how power electronics contribute to sustainability and efficiency. The article further explores the role of power electronics in communication networks, including broadband power line communication, power supply in data centers, and wireless power transfer. Each section underscores the significance of power electronics in driving efficiency, sustainability, and technological advancement in infrastructure development. The article emphasizes the need for ongoing innovation in power electronics to meet the challenges of a rapidly evolving global landscape and ensure resilient, adaptive, and environmentally responsible infrastructure.

Electric Railway System Integrated with EV Charging Station Realizing Train-to-Vehicle Technology

Electric Railway System Integrated with EV Charging Station Realizing Train-to-Vehicle Technology

A new distributed voltage control method for MVDC electric railway systems with renewable energy sources

The medium voltage DC (MVDC) electric railway system is one of the most interesting options for future high-speed rail (HSR) lines. The dc voltage control is one of the most critical challenges of MVDC electric railway systems due to various reasons such as simultaneous, continuous and considerable changes in the power and location of trains, regenerative brake energy of trains, long power lines, the application of ESS’s and RES’s. In this paper, a voltage control, i.e., the optimal-voltage voltage-power (OVVP) control method, is presented for MVDC electric railway systems. OVVP control method is a practical, reliable, automatic, and modular distributed voltage control method. The proposed voltage control method satisfies the nearest voltage to the nominal value in each node and the smoothest voltage profile in different MVDC electric railway systems. Although the analyses carried out in this paper analytically prove the significant performance of the presented voltage control method, different challenging scenarios are considered to verify OVVP control method more. In addition, the results of the proposed voltage control method are successfully validated by GAMS software.

Impacts of Dynamic Frequency Feedback Loop in SOGI-PLL on Low-Frequency Oscillation in an Electric Railway System

The low-frequency oscillation (LFO) issue has occurred frequently in single-phase electric train and traction network interactive systems (hereinafter train-network systems). On a single-phase electric train, the second-order generalized integrator (SOGI) based phase-locked loops (PLLs) have been widely used and also have significant impacts on the LFO. In the SOGI-PLL, the frequency signal is dynamically feedback from PLL to SOGI for adapting frequency variety, which causes complex nonlinearity and may deteriorate the small-signal stability of train-network systems. In previous works, the small-signal impedance model of train supposes that the feedback frequency is quasi-steady-state, which ignores impacts of dynamic frequency feedback loop (DFFL) on system-level stability and causes inaccurate analysis results. Therefore, this article builds an improved impedance model of train in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> frame with considering the DFFL. Compared with fixed frequency feedback loop (FFFL) based SOGI-PLL, the DFFL-based SOGI-PLL results in an additional negative resistance behavior, which is more likely to induce the LFO. Moreover, based on proposed impedance model of train, three FFFL-based SOGI-PLLs are compared among the filtering capability, phase-locked error and negative resistance range. Finally, experiment results by hardware in the loop (HIL) platform and real low-power experimental platform are employed to verity the correctness of theoretical analysis results.

Energy Management Systems for Smart Electric Railway Networks: A Methodological Review

Energy shortage is one of the major concerns in today’s world. As a consumer of electrical energy, the electric railway system (ERS), due to trains, stations, and commercial users, intakes an enormous amount of electricity. Increasing greenhouse gases (GHG) and CO2 emissions, in addition, have drawn the regard of world leaders as among the most dangerous threats at present; based on research in this field, the transportation sector contributes significantly to this pollution. Railway Energy Management Systems (REMS) are a modern green solution that not only tackle these problems but also, by implementing REMS, electricity can be sold to the grid market. Researchers have been trying to reduce the daily operational costs of smart railway stations, mitigating power quality issues, considering the traction uncertainties and stochastic behavior of Renewable Energy Resources (RERs) and Energy Storage Systems (ESSs), which has a significant impact on total operational cost. In this context, the first main objective of this article is to take a comprehensive review of the literature on REMS and examine closely all the works that have been carried out in this area, and also the REMS architecture and configurations are clarified as well. The secondary objective of this article is to analyze both traditional and modern methods utilized in REMS and conduct a thorough comparison of them. In order to provide a comprehensive analysis in this field, over 120 publications have been compiled, listed, and categorized. The study highlights the potential of leveraging RERs for cost reduction and sustainability. Evaluating factors including speed, simplicity, efficiency, accuracy, and ability to handle stochastic behavior and constraints, the strengths and limitations of each optimization method are elucidated.

EMI and IEMI Impacts on the Radio Communication Network of Electrified Railway Systems: A Critical Review

The electrified railway system has been rapidly rolled out in many countries and regions in the past decades, along with the transportation decarbonization agenda. The latest development in power electronics and electrical railway systems has increased the risks of electromagnetic interference (EMI) and intentional EMI (IEMI) emissions, introducing new challenges to the railway radio communications network. It is vital to have a robust and reliable railway communication network that can be resistant and immune to these interferences for the safe and efficient operation of modern railway systems. Yet, the source and new features of EMI and IEMI emerging along with the latest technological development have not been thoroughly investigated and understood. This review paper aims to fill the research gap. First, railway communications systems are introduced. The EMI and IEMI are discussed at the whole system level, and the corresponding impacts on the signaling and communication systems are reviewed comprehensively. Current electromagnetic compatibility (EMC) methods are surveyed, and challenges of tackling the impacts of EMI and IEMI on the signaling and communication systems are discussed. Finally, future research directions are outlined.

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.

Optimal P2P based energy trading of flexible smart inter-city electric traction system and a wayside network: A case study in Alexandria, Egypt

In an open energy market, the peer-to-peer (P2P) energy trading policy became more applicable. Therefore, while planning for new electrified systems, such a trading policy is taken into consideration. On the other hand, as the electrification of railway systems along with the use of electric vehicles serve several sustainable development goals, plans are studied for the electrification of the inter-city railway system in Alexandria, Egypt, in order to connect it with the high-speed inter-provincial electric railway system. In addition, other plans are studied for local production of electric vehicles. For this purpose, this paper presents a study regarding P2P based optimal energy management (EM) of a flexible smart railway substation taking into consideration multiple energy sources of the traction system and the wayside distribution network. The energy sources of the substation include captured regenerative braking energy (RBE), photovoltaic (PV) units and a multistory parking garage of electric vehicles (EVs). The wayside distribution network also contains several energy sources including distributed generation and multiple energy hubs (EHs) in addition to district distribution area with flexible loads. Optimal energy management is carried out including optimal demand side management of flexible loads and EHs. The optimization study takes into consideration several operational uncertainties arising from several components of the system. The simulation results show the feasibility of applying the proposed EM algorithm with an improvement of the energy economics of the system.

Superconducting DC power transmission for subway lines that can reduce electric resistance and save energy

Electric railway systems are widely used and DC systems have been employed in a number of metropolitan areas. However, they have some problems, such as cancelled regeneration and energy loss. Introducing superconducting feeder cables into railway feeding systems offers a lot of benefits: fewer substations, equalization of load among substations, reduction of cancelled regeneration, power transmission loss. Feeding systems adopted by railways throughout the world can be classified into feeding systems through overhead trolley wires and ground third rails. These problems are especially serious in third rail system because the voltage is low and the electric current is high. By using a newly developed superconducting feeder system on a third rail system, we conducted a power transmission test. Also, the feeding of the high current and regeneration current was proved to be successful in the course of the train running test on subway line. And, we specifically analyzed the energy generated when a cable was adopted into the third rail line. As a result of adoption of a superconducting feeder cable, the voltage drop specific to railways could be reduced even with a short cable. And, if the cable is adopted in subway line, we also observe large energy-saving effect.

An innovative application of pantograph recognition system based on deep learning

One of the most significant aspects for the correct operation of a modern railway electrification system is the health of the pantograph and overhead line. The application of machine vision technology to monitor the status of pantographs in real time can reduce pantographs and catenary accidents caused by unpredictable events. It is challenging to achieve real-time and accurate criteria with present pantograph detecting technologies. Therefore, this methodology collects pantograph images through high-definition cameras and transmits them to the cloud through 5G, use the Mask R-CNN algorithm to process and analyse the images., This technology can assist railway technicians in judging the status of the pantograph. Mask R-CNN employs the Resnet network for feature extraction. Resnet has the characteristics of cross-layer connection, which avoids the problem of network degradation due to the deep learning network being too deep, and greatly improves the training efficiency. The recognition matching degree of pantographs are greater than 0.975, enabling pantograph recognition in a variety of environmental conditions. The use of 5G connection increases transmission speed and allows for real-time detection of pantograph status, which is critical for the railway's automated operation.

QUALITY ASSURANCE DURING TRANSPORTATION IN RAILWAY VEHICLES

Regional cooperation in rail transport can help participating countries diversify their trade patterns. Improved rail transport can also help attract foreign direct investment, increase participation in global production networks and the scale of related trade in manufactured goods, and diversify exports. Improved rail infrastructure will increase global competitiveness and spur economic development. In addition, improved rail infrastructure will help regional cooperation and integration through improved connectivity between people, goods and services. The operation is carried out by a railway company, providing transport between train stations or freight customer facilities. Power is provided by locomotives which either draw electric power from a railway electrification system or produce their own power, usually by diesel engines or, historically, steam engines. Most tracks are accompanied by a signalling system. Railways are a safe land transport system when compared to other forms of transport. Railway transport is capable of high levels of passenger and cargo utilisation and energy efficiency but is often less flexible and more capital-intensive than road transport, when lower traffic levels are considered. Railways are a climate-smart and efficient way to move people and freight. Keywords: railway, transport, improvement, transportation, transit, passenger, development, delivery, traffic, technology, vehicles.

Power Quality Problems of the Electrified Railway and Its Control Methods

In developing the railway industry, the electrified railway plays a significant role in improving the national economy. However, the electric railway power supply system will be affected by power quality problems such as negative sequence, harmonic, and voltage fluctuation in actual operation, which will affect the operation efficiency of the electric railway power supply system. Therefore, it is meaningful to take economic and effectual governance measures against the power quality problems of electrified railways and reduce various indicators to the range allowed by a national standard. This paper summarizes and sorts out the main problems and their causes of current electrified railway power quality and several existing mainstream power quality governance schemes. It analyzes their advantages and disadvantages and finally looks forward to the directions that can be optimized and improved in the future study of electrified railway power quality problems in combination with social reality. It has a specific guiding effect on future research on electrified railway power quality.

An Improved Q-Axis Current Control to Mitigate the Low-Frequency Oscillation in a Single-Phase Grid-Connected Converter System

An electric railway system is a typical single-phase grid-connected converter system, and the low-frequency oscillation (LFO) phenomenon in electric railway systems has been widely reported around the world. Previous research has indicated that the LFO is a small-signal instability issue caused by impedance mismatching between the traction network system and electric trains. Therefore, this paper proposes an improved q-axis current control method to reshape the train’s impedance. The proposed method can be implemented easily by relating a reverse q-axis reactive current directly to the reference of the q-axis current under the dq current decoupled control. Moreover, considering the additional q-axis reactive current control, a small-signal impedance model of a train–network system is built. The impedance-based analysis results indicate that the proposed q-axis reactive current feedback control can increase the magnitude of the train’s impedance, which is beneficial to enhancing the system’s stability. Finally, this paper employs experimental results to verify the effectiveness of the proposed method.