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Review of Research on Lightning Interaction with the Swedish Railway Network
Uppsala University.
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2008 (English)Conference paper (Refereed)
Abstract [en]

In the early electrified railway systems, the design of signal and control networks were not always made in accordance with the strict rules of Electromagnetic Compatibility (EMC). This created problems due to Electromagnetic Interference (EMI) when old electro-mechanical signalling, control and communication systems were replaced by modern sensitive electronic circuits. Modern developments in the railway systems have made the system more vulnerable to lightning transients, a natural source of EMI, because the overall network is not designed to reduce the lightning surges to the low levels tolerable to the electronic systems widely being introduced in the railway system. Railway networks are extensive and modernization of signal/control/communication systems are carried out in stages at different times, it is not unusual to find transient related problems in a section of the network on account of inadequate lightning protection design or EMC design of the existing network in which a new module (equipment or system) is introduced. These problems may act as a brake on the upgrading plans of the railways. Also the new railway systems which incorporate advanced signal/control/communication systems sometimes suffers from the effects of lightning transients because many of the standards and guidelines used in the design dates back to the age of electromechanical devices and hence do not include robust transient protection design. There have been many attempts to address EMC issues in railways, but usually these attempts were confined to solving immediate problems of EMI due to introduction of new locomotive drives and EMI due to sparks at the pantograph. A comprehensive review of railway system from the angle of lightning protection and EMC is not yet fully carried out.

The Swedish National Rail Administration (Banverket) reported a delay of about 900-1000 hours in the years 2001-02. Lightning transients were found to damage important devices that control train movements, causing traffic stoppage and delays. This work therefore discusses the EMC problems of large distributed systems, with particular reference to lightning interaction with Swedish rail networks [1]. Lightning induces transient overvoltages in railway conductor systems such as tracks, overhead wires, and underground cables, either due to direct lightning strike to the system or due to the coupling of electromagnetic fields from remote strikes. Models based on multiconductor transmission line theory were developed for calculating the induced voltages and currents [1-3]. Some experiments have also been carried out to better understand the way in which the lighting transients’ couple into the systems and also to verify the models used for analysis [4]. From experiments high frequency behavior of different types of transformers used within the railway systems were also derived [1, 6].  Besides, experimental studies on lightning induced transients entering railway systems, failure modes of relay and rectifier units used in the train position/signaling applications for lightning transients are performed. The simulation models are being converted to user friendly software for the practicing engineers of the railway industry [1].

Place, publisher, year, edition, pages
URN: urn:nbn:se:kth:diva-11935OAI: diva2:290560
Presented at the EuroEM Conference 2008, Lausanne, SwitzerlandAvailable from: 2010-02-04 Created: 2010-01-27 Last updated: 2010-04-28
In thesis
1. Multi-conductor transmission line model for electrified railways: A method for including responses of lumped devices
Open this publication in new window or tab >>Multi-conductor transmission line model for electrified railways: A method for including responses of lumped devices
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For studying the response to transients caused by lightning and other electromagnetic disturbance sources, electrified railway systems can be represented as a system of multiconductor transmission lines (MTL) above a finitely conducting ground. The conductors present in this system would be wires for traction power supply, auxiliary power, return conductors for traction current, the tracks, and finitely conducting ground. In contrast to conventional power systems, where the MTL system is usually only terminated at the line ends, there are lumped devices connected in series and as shunt along the railway network, for example, booster and auto transformers, track circuits, and various interconnections between conductors, influencing surge propagation. In this doctorial thesis a new method for incorporating lumped series and shunt connected devices along MTL systems is presented. Telegrapher’s equations, using the finite difference time domain method, are adopted for finding surge pulse propagations along the MTL systems, simultaneously solving for the lumped devices connected along the lines by means of Kirchoff’s laws for nodal currents and voltages using a circuit solver.

As part of this work, case studies are carried out to determine voltages appearing across devices connected along MTL systems representative of a typical Swedish single-track electrified railway system, in cases of direct and indirect lightning strikes. The influence of soil ionization at the grounding points and the nonlinear phenomenon of flashovers between overhead wires and the poles are also investigated. The calculations made show that the devices connected along this system, which are needed for normal and safe operation of the railway system, and nonlinearities are affecting the surge current and voltage distribution and peaks appearing along the MTL system and across devices.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. x, 80 p.
Trita-EE, ISSN 1653-5146 ; 2010:006
urn:nbn:se:kth:diva-11964 (URN)978-91-7415-557-0 (ISBN)
Public defence
2010-02-24, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Available from: 2010-02-01 Created: 2010-02-01 Last updated: 2012-03-26

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Mazloom, Ziya

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