Investigation of the rail potential of ac. traction systems with different feeding systems under normal operation and fault condition

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Dr. Varjú György
Department of Electric Power Engineering

Railway transportation is experiencing its renaissance in many European and Far-Eastern countries nowadays. This tendency is largely due to the fact that electric rail traction gains more and more importance as it is an environmentally friendly way to perform both high-speed passenger transportation and freight operations with great efficiency. To maintain this progress it has become necessary to increase electric power, along with the further improvement of safety and reduction of disturbing electric factors. Efforts have been made to reduce rail potentials as well as inductive and conductive effects that derive from the specific features of earth return current. In my thesis I examine the rail potentials of different a.c. feeding systems.

The first chapter of the thesis will give a brief historical overview of the evolution of electric railway systems in general and its development in Hungary.

I introduce the structure of the electric traction system and the different 25 kV a.c. feeding systems with 50Hz frequency used today.

In the second part I introduce the main formulas of rail potentials and the current distribution of the compensating conductors. I also review the methods and principles used by the simulation software for calculation.

In the third part of the thesis I analyze the results of the simulation test of a.c. feeding systems of MÁV using the simulation software MULTC. The rail potentials and the current distribution of the compensating conductors are the subject of my study.

Lastly I give a final evaluation of those results of the simulation test that refer to the rail potentials by comparing the different a.c. systems.


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