Scientific paper ID 2464 : 2024/2

In this report, actual measurements have been made over a period of time on a step-down transformer with one DC charging station and four AC charging stations for electric vehicles connected to the low voltage side, the latter are not considered in this report. The aim is to analyse the impact of the DC charging station on the power quality performance and, in particular, its impact on the power factor cosφ of the primary side of the step-down transformer.

The power indices of the medium voltage and low voltage side of the step-down transformer station at the Todor Kableshkov University of Transport at the time of charging station operation are investigated. The measurements were made on the supply branch of the charging stations and on the medium voltage side of the step-down transformer. A comparative analysis of cosφ, which determines the reactive energy on the primary side of the transformer, was made.

The measurements made relate to the change in power quality from the connected DC EV charging station to the low voltage side. The measurements are at different transformer loads in all secondary branches. During the study, the transformer load is in a wide range due to the varied commodity schedule and independent of the charging station operation.