Marcin Steczek

Due to energy saving policy in the European Union and development of power electronics technology, one might expect an increase in the use of solutions, such as inverters in the substations of the 3 kV DC power supply system. The paper includes a study case of the analysis of traffic conditions on the use of inverters in 3 kV DC system traction substations so as to send back trains’ braking energy from a DC traction power supply to an AC power supply network. The authors presented possible estimated energy savings for a selected railway line. Furthermore, the character of a power waveform and energy available for transferring from a DC to an AC power supply network was discussed as well. The effectiveness of this solution largely depends on the nature of train traffic, so prior to applying the inverters, a detailed analysis is required.

In this paper, a basic function of an Automatic Train Operation (ATO), called target braking, has been discussed. The most important assumptions of this function have been discussed in detail. The SOP-2 system designed by the Technical University of Lodz, in cooperation with Bombardier Transportation (ZWUS), has been presented. In the text, a target braking simulation model created by the authors has been described, which was developed to study the impact of the propulsion system on the target braking accuracy. The simulation results have been presented. The average dispersion of automatic target braking provides train stopping in the most number of cases in the range of 0.53 meters. Target braking values obtained during field tests are in the range from 0.3 to 1 meter. On the basis of the obtained results of target braking, the process conclusions are as follows: rapid deceleration changes cause the so-called jerks, which are negatively perceived by the passengers; braking in a long time causes a decrease in the commercial speed. Currently, the authors have developed a simulation model that includes a DC motor drive, which is in the testing phase.