Scientific paper ID 2642 : 2025/1

In the Republic of Bulgaria, the classical urban electric transport system-Traction rectifier stations (TRS), overhead contact networks (OCN), and electric vehicles such as trolleybuses and trams (in cities like Sofia) - operates in 10 cities. Over the past 15 years, investments appear to have focused primarily on the acquisition of new autonomous transport vehicles, such as battery-powered electric buses and charging stations. Except for a few cities like Sofia, Vratsa, and Pleven, investments in the modernization of the classical infrastructure, including the overhead contact network and rectifier stations, have been significantly limited. This is since the political impact of purchasing new vehicles is greater compared to investing in RS—an infrastructure element that remains ”invisible” to the public.

This report examines the state of TRS in the municipal towns of Bulgaria where electric transport is operated, excluding Sofia. In most of these towns, the TRS were commissioned during the 1980s and are now both technically and morally outdated. The current analysis explores the electrical parameters of six-pulse rectifiers used in these stations. The report s results from simulations conducted using MATLAB Simulink as well as experimental measurements taken during the operation of such rectifiers.

The main objective is to assess the condition of existing TRS, identify their key shortcomings, and propose opportunities for modernization.