Thesis-2008-Ogunsola.pdf (7.17 MB)
Railway interference management: TLM modelling in railway applications
thesis
posted on 2016-02-03, 10:14 authored by Adesegun A. OgunsolaThis thesis deals with the application of analytical and numerical tools to
Electromagnetic Compatibility (EMC) management in railways. Analytical
and numerical tools are applied to study the electromagnetic coupling from an
alternating current (AC) electrified railway line, and to study the electrical
properties of concrete structure - a widely used component within the railway
infrastructure. An electrified railway system is a complex distributed system
consisting of several sub-systems, with different voltage and current levels,
co-located in a small area.
An analytical method, based on transmissions line theory, is developed to
investigate railway electromagnetic coupling. The method is used to study an
electrified railway line in which the running rails and earth comprise the
current retum path. The model is then modified to include the presence of
booster transformers. The analytical model can be used to study the railway
current distribution, earth potential and electromagnetic coupling - inductive
and conductive coupling - to nearby metallic structures. The limiting factor
of the analytical model is the increasing difficulty in resolving the analytical
equation as the complexity of the railway model increases.
A large scale railway numerical model is implemented in Transmission Line
Matrix (TLM) and the electromagnetic fields propagated from the railway
model is studied. As this work focuses on the direct application of TLM in
railway EMC management, a commercially available TIM software package is
used. The limitation of the numerical model relates to the increased
computation resource and simulation time required as the complexity of the
railway model increases.
The second part of this thesis deals with the investigation of the electrical
properties of concrete and the development of a dispersive material model
that can be implemented in numerical simulators such as TIM. Concrete is
widely used in the railway as structural components in the construction of
signalling equipment room, operation control centres etc. It is equally used as
sleepers in the railway to hold the rails in place or as concrete slabs on which
the whole rail lines are installed. It is thus important to understand the
contribution of concrete structures to the propagation of electromagnetic
wave and its impact in railway applications.
An analytical model, based on transmission line theory, is developed for the
evaluation of shielding effectiveness of a concrete slab; the analytical model is
extended to deal with reinforced concrete slab and conductive concrete. The
usefulness and limitation of the model is discussed. A numerical model for
concrete is developed for the evaluation of the effectiveness of concrete as a
shield. Initially, concrete is modelled as a simple dielectric material, using the
available dielectric material functionality within TLM.
It is noted that the simple dielectric model is not adequate to characterise the
behaviour of concrete over the frequency range of interest. Better agreement
is obtained with concrete modelled as a dispersive material having material
properties similar to that exhibited by materials obeying Debye equation. The
limitations of the dispersive material model are equally discussed.
The design of conductive concrete is discussed, these have application in the
railway industry where old existing structures are to be converted to
functional rooms to house sensitive electronic system. A layer of conductive
concrete can be applied to the facade to enhance the global shielding of the
structure.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Publisher
© Adesegun A. OgunsolaPublisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2008Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.Language
- en