Optimizing the train-catenary electrical interface in AC railways through dynamic control reconfiguration

Abstract

The power supply architecture of most AC electric railway vehicles is constituted by transformers and catenaries at increasingly high power levels. Inside the vehicles, the interface between the catenary and the DC-bus of the traction motors is based on a transformer and power electronics converters. A large part of these are AC-DC four quadrant converters that operate in parallel at relatively small switching frequencies. However, the use of the interleaving principle allows reaching a low harmonic distortion of the catenary current and imposing specific harmonic ranges in this current. Nevertheless, the current is not a pure sinusoidal wave and its harmonics can excite unwanted resonances due to the combined effect of the catenary distributed parameters, the substation equivalent impedance and the current frequency spectrum. This paper analyses this phenomenon and proposes a control strategy capable of minimizing the resonance effects in two different power supply architectures.