Parametric analysis of 2 × 25 kV railway electric supply

Abstract

The most common system for railway high-speed lines electric supply and the somehow de-facto standard is a special AC industrial frequency system called 2 × 25 kV system. Although several studies exist showing the performance of this system in frequency and time domains, there is a lack of studies analysing how geometric parameters influence the system behaviour, mainly in terms of conductor currents. This study first introduces a simple analytic model able to explain the fundamental feats of 2 × 25 kV systems, then evaluates the effects of critical electrical and geometrical parameters on this behaviour based on mathematical relationships and numerical computations. This simple model allows understanding the main reasons why this system is able to transmit power as a 50 kV system, while trains experience just 25 kV.