Impacts of Home Electric Vehicle Chargers on Distribution Transformer in Thailand

We study impacts of electric vehicle (EV) home chargers on a typical three-phase distribution transformer (DTR) in distribution grid. We focus on the DTR loading and voltage imbalance. We focus on the distribution grid operated by the Provincial Electricity Authority (PEA), which is a major utility provider in Thailand. We determine the maximum number of the EV chargers that can be supported by a DTR assuming the current typical base load profile and no coordinated charging scheduling exists (that is, the EV chargers start operation right at the time they are plugged in). For the typical base load profiles, we found that that DTR loading is more critical than the voltage imbalance and the maximum number of EV's per phase is 3, 6, 10, and 14 for the 50, 100, 160, and 250 kVA DTR, respectively.