Impact Analysis of Electric Vehicle Quick Charging to Power Transformer Life Time in Distribution System

This paper presents the study of electric vehicle (EV)'s quick charging affecting against the insulation life time of the 115/22 kV power transformer in Provincial Electricity Authority of Thailand (PEA) substation. The Simulink model of EV is developed to represent the actual characteristic of EV charging. Then this model is used to construct the load profile of each EV charging station based on the statistical data. The study area is Bang Lamung district of Chonburi province which is assumed that there are quick charging stations among 30 existing petrol stations for 200 EVs per station. The investigation of total load profile of 115/22 kV power transformer in PEA Bang Lamung substation is performed according to IEEE C57.91-2011 to evaluate the impact of transformer life time. From the simulation results it shows that EV quick charging during 7:00-11:00 pm has significant impact on power transformer overloading due to the winding hot spot temperature and has caused the diminishing of power transformer life time.