Current Railway System Research Articles

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

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.

New Anti-Derailment System in Railway Crossings

The objective of this paper is to design a new system to reduce the risk of derailment at crossings, which are critical points in railway lines. Crossings are a common element in conventional lines of current railway systems and are the only point on the track where there is a discontinuity. Our proposal is based on adding an element to the crossing that occupies part of the crossing gap, providing a larger support surface next to the wing rail, such that the wheel does not fall into the gap. The lateral force—which is the most influential parameter in derailments—is substantially decreased, thus reducing the risk of derailment due to lifting on the rail. The proposed approach also increases the safety of the dynamic behaviour, which has a direct impact on passenger comfort and influences the service life of both the rolling stock and the track, thus reducing the cost and even increasing safety at higher speeds. It has a simple structure that is easy to assemble and does not interrupt traffic during installation. The results of simulations using this innovative solution indicate a significant reduction in lateral stresses and strains on the track, which undoubtedly produces an improvement in traffic safety; however, the results cannot be fully quantified in terms of accident reduction with only the data obtained from simulations. Therefore, it was concluded that implementation of the new crossing design provides better conditions for rolling stock to run on turnouts, increasing safety by reducing the risk of derailment. Nevertheless, it will be necessary to carry out a program of experimental tests, which we intend to make the subject of future research.

Adaptive Partial Train Speed Trajectory Optimization

Train speed trajectory optimization has been proposed as an efficient and feasible method for energy-efficient train operation without many further requirements to upgrade the current railway system. This paper focuses on an adaptive partial train speed trajectory optimization problem between two arbitrary speed points with a given traveling time and distance, in comparison with full speed trajectory with zero initial and end speeds between two stations. This optimization problem is of interest in dynamic applications where scenarios keep changing due to signaling and multi-train interactions. We present a detailed optimality analysis based on Pontryagin’s maximum principle (PMP) which is later used to design the optimization methods. We propose two optimization methods, one based on the PMP and another based on mixed-integer linear programming (MILP), to solve the problem. Both methods are designed using heuristics obtained from the developed optimality analysis based on the PMP. We develop an intuitive numerical algorithm to achieve the optimal speed trajectory in four typical case scenarios; meanwhile, we propose a new distance-based MILP approach to optimize the partial speed trajectory in the same scenarios with high modeling precision and computation efficiency. The MILP method is later used in a real engineering speed trajectory optimization to demonstrate its high computational efficiency, robustness, and adaptivity. This paper concludes with a comparison of both methods in addition to the widely applied pseudospectral method and propose the future work of this paper.

토지피복지도를 활용한 철도개발지의 민감도 분석

최근 한반도 생태축의 근간을 이루는 백두대간의 중심에 위치한 추풍령 생태축 연결 복원사업이 추진되고 있으며, 이 지역은 일제 강점기에 경부선 철도건설과 함께 산업화 과정에서 도로와 철도 건설 등에 의해 야생동물의 이동이 단절되어 로드킬의 주요 원인이 되어 온 것으로 지적되었다. 그러나 친환경적 교통수단인 철도에 대한 투자 비중이 증가하는 추세를 보이고 있으며, 현재 기존 선로의 고속화를 위한 단선철도의 복선전철화 및 선형개량 사업 등 전국 철도망이 지속적으로 확대되고 있다. 이에 따라 본 연구는 급증하는 철도노선 연장에 따른 국토공간의 생태적 취약성을 평가하는 주요 평가기준으로 토지이용을 검토할 것을 제안하였고, 환경부에서 제공하는 토지피복지도를 활용하여 철도노선과 중첩분석을 수행하였다. 그 결과 논, 밭, 활엽수림, 나지, 내륙수 등 5개 항목에 민감도가 높은 것으로 나타났다. 이러한 항목들에는 민감도에 따른 가중치 설정이 필요한 것으로 생각되며 이를 바탕으로 구체적인 평가 기준을 마련할 필요가 있다. Recently, the 'Ecological Network Restoration Project at Chupungnyeong' has been placed; this project is located at the center of the Baekdu mountain spine, the core of the ecological network of the Korean Peninsula. In the process of industrialization since the early 1900s, this area has been under railroad and road construction; as such, wildlife movements have been interrupted and many cases of road-kill have been found. The investment in railroads has increased because railroads are an environmentally sound means of transportation. Single track railways have been converted to double track electric railways and track reforming projects are underway in order to speed up the current railway system. This study suggests to take land use as a standard for assessing the ecological weaknesses of the domestic geo-spaces that are to be affected by rapid extension of railway lines. The land cover map issued by the Ministry of Environment was overlapped with the Korean Railway Line Map for analysis. The results showed that five items were high in sensitivity: paddy fields, fields, deciduous forests, bare land, and inland waters. It seems to be necessary to set weights for highly sensitive land use types; also, specific evaluation criteria need to be reestablished.

Are railways really that bad? An evaluation of rail systems performance in Europe with a focus on passenger rail

With a large number of railway development projects in Europe and worldwide, which once completed will be serving rail passengers of the future, this paper aims to take a step back and evaluate current railway systems performance. The objectives are to compare statistical data on various passenger-related parameters of the railway system in a number of selected European countries and draw conclusions on the level of their performance when compared to the European average.Analyses of publically available statistical data, extracted from the Eurostat service at a European level will allow for a comparison of various indicators which influence the performance of the railway systems from an infrastructure and operational perspectives. The analyses will also allow identifying key performance indicators for the accurate assessment of the rail systems.The paper will highlight case studies for various parameters which are important to stakeholders of the railways, including infrastructure managers, rail operators, policy makers and the end users. This knowledge will be to the benefit of today’s railway industry as well as the rail systems of the future, as it will show trends drew upon existing data which might continue in the future.

Optimisation models for expanding a railway's theoretical capacity

Changing the topology of a railway network can greatly affect its capacity. Railway networks however can be altered in a multitude of different ways. As each way has significant immediate and long term financial ramifications, it is a difficult task to decide how and where to expand the network. In response some railway capacity expansion models (RCEM) have been developed to help capacity planning activities, and to remove physical bottlenecks in the current railway system. The exact purpose of these models is to decide given a fixed budget, where track duplications and track sub divisions should be made, in order to increase theoretical capacity most. These models are high level and strategic, and this is why increases to the theoretical capacity is concentrated upon. The optimisation models have been applied to a case study to demonstrate their application and their worth. The case study evidently shows how automated approaches of this nature could be a formidable alternative to current manual planning techniques and simulation. If the exact effect of track duplications and sub-divisions can be sufficiently approximated, this approach will be very applicable.

Design of Wireless Power Transfer System for Railway Application

As wireless power transfer (WPT) technologies emerge in a wide range of applications including public transportation, many expect that applying the technology to the current railway systems will bring positive effects to current railway systems. In this paper, we introduce design methodology of a WPT system for railway application. Fundamental principles of magnetic fields and a WPT circuit are first analyzed, and advantages and efficiency of a possible train system are discussed. It then examines other significant factors such as performance requirements and EMC criteria to design a wireless train system.

Efficient Multisensory Barrier for Obstacle Detection on Railways

On current railway systems, it is becoming ever more necessary to install safety elements to avoid accidents. One of the causes that can provoke serious accidents is the existence of obstacles on the tracks, either fixed or mobile. In this paper, a multisensory system that can inform the monitoring system about the existence of obstacles is proposed. The system for obstacle detection consists of two emitting and receiving barriers, which are placed on opposing sides of the railway, respectively, and use infrared and ultrasonic sensors, thus establishing different optical and acoustic links between them. The interruption of one or several links should produce an alarm. However, even without the existence of objects, degradation of links could occur due to atmospheric attenuation, solar radiation, etc., also producing an activation of the alarm system. Since detection is based on the lack of radiation in the detectors, the use of complementary sensors for the same task is justified. Since the minimum size of an object for which an alarm is required to be generated is 50 × 50 × 50 cm, in some situations, several links are interrupted; however, alarms should not be generated. Typical cases are the flight of leaves or the movement of small animals in the scanned area. To avoid alarm activation in such situations, this paper proposes the combined use of diverse techniques of data fusion, based on fuzzy logic and the Dempster-Shafer theory of evidence, to validate the existence of objects, providing a highly reliable detection system.

21208 架線・パンタグラフ間における接触力の基礎的考察(材料力学(2),一般講演,学術講演)

The contact problems between a rigid trolley and a pantograph in a current railway system are studied from the viewpoint of nonlinear dynamics. It is assumed that there are the contact force between the rigid trolley and the pantograph due to the corrugated wear of the rigid trolley. The rigid trolley-pantograph system has been modeled with a spring-supported mass excited by an oscillating plate. Using this essential model, the influences of the car speed and the corrugated wear of the rigid trolley between the spring-supported mass and the oscillating plate were examined theoretically and numerically. Moreover, the experiments are conducted with the essential model, of which the motion takes place in a mechanically similar manner with the rigid trolley pantograph system.

Fundamental Study on Impact Oscillations of Rigid Trolley-Pantography System

The contact problems between a rigid trolley and a pantograph in a current railway system are studied from the viewpoint of nonlinear dynamics. It is assumed that there are the impact oscillations between the rigid trolley and the pantograph due to the corrugated wear of the rigid trolley. The rigid trolley-pantograph system has been modeled with a spring-supported mass excited by an oscillating plate. Using this essential model, the influences of the car speed and the corrugated wear of the rigid trolley on the bouncing phenomena between the spring-supported mass and the oscillating plate were examined theoretically and numerically. Moreover, the experiments are conducted with the essential model, of which the motion takes place in a mechanically similar manner with the rigid trolley pantograph system.

架線・パンタグラフ系における離線現象の基礎的考察 : 舟体の弾性振動の効果(機械力学)

In a current railway system, there is a problem that pantographs are sometimes detached from catenary. The faster the train becomes, the more problematic it would be. We investigate experimentally and discuss the problem using the simple model, of which the motion takes place in a mechanical similar manner with the real pantograph.

3902 周期的に加振されるばね・質点系の衝突・接触振動

The contact problems between a catenary and a pantograph in a current railway system are studied from the viewpoint of nonlinear dynamics. Using a simple model of the system, i.e. a spring-supported mass system, the bouncing phenomena between a spring-supported mass and a periodically excited plate are examined theoretically and experimentally.