Estimation of capacity for charging electric vehicles

The growing consciousness for increased environment protection has made Electric Vehicles (EV) a more attractive and practical alternative to the internal combustion engine car. The increasing number of EVs connected to power systems for charging will have a significant impact on the operating performance of power systems. This paper proposes a methodology to determine the maximum number of EVs that can be charged by estimating the loading capacity of a transformer. The EVs are charged according to users driving requirements while respecting the constraints of the local distribution network. Analysis of transformer dynamic thermal performance is used to determine the maximum allowable load on a transformer. Results show that more EVs can be charged when using the dynamic thermal rating rather than the static thermal rating. The estimated capacity indicates the maximum number of EVs that can be charged, if the normal operation of the power system must be maintained.