Energy efficiency of a railway line supplied by 3 kv supply system – a case study of the application of an inverter in a traction substation

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.