Scientific paper ID 2274 : 2022/3

The Sofia subway is the most important transport artery of the public mass urban transport. Passenger comfort and safety are constantly being improved. Along with this, however, attention should also be paid to the energy efficiency of traction energy supply networks.

The article presents and analyzes data gathered from the research of current, voltage, active power (P), reactive inductive (Qi) and reactive capacitive power (Qc), cosφ and others. There are shown different traction units (TRUs), that are in operation in the traction reduction stations (TRS) of the capital subway. The behavior of the energy indicators in different operating modes of the transformers has been examined. This article also analyzes the reasons for the low values of the power factor and the presence of capacitive energy, which leads to the deterioration of the quality of electrical energy and to penalties.