Influence of EV Charging Stations on the Performances of Three-Phase Distribution Transformers in Residential Grids

Electric vehicle charging stations significantly impact the performance of three-phase (11/0.4 kV) distribution transformers, as unbalanced and variable loads lead to higher temperatures and increased power loss. They also contribute to reduced transformer life and increased risk of failure. This paper demonstrates the impact by analyzing the challenges arising from the nonlinear and variable nature of electric vehicle charging loads, such as harmonic distortions, electrical stresses, and voltage imbalance. The electrical network was simulated using the Electrical Transient Analyzer Program (ETAP) software, and the potential risks to (11/0.4 kV) distribution transformers due to nonlinear and variable charging loads were identified. The results revealed that the distribution transformer's capacitance near to the loads (T3) suffered a 12.40 % voltage drop at full load. On the other hand, the total distortion on the secondary side of the transformer (T3) reached 55.71% for a six-pulse, single-harmonic IEEE source and 40.53% for a twelve-pulse, single-harmonic IEEE source. This analysis indicates a potential risk to transformer performance, which calls for consideration of adding harmonic filters to improve power quality. It also aims to enhance the reliability and efficiency of converters by providing accurate analyses and simulations of the impact of electric vehicle charging stations on converter performance.