What are the implications of widespread adoption of electric vehicles (EVs) on distribution transformer loading and thermal aging?

Electric vehicle (EV) charging places significant new demands on distribution transformers. Widespread EV adoption leads to increased peak demand, particularly during evening hours when residents return home and plug in their vehicles. This increased demand can push distribution transformers closer to, or even beyond, their rated capacity. Distribution transformers are designed to operate within specific temperature limits. Exceeding these limits accelerates the thermal aging of the transformer's insulation. Thermal aging is the degradation of the insulating materials (typically oil and paper) due to prolonged exposure to high temperatures. The rate of thermal aging increases exponentially with temperature. Overloading a transformer shortens its lifespan and increases the risk of failure. Furthermore, EV charging often introduces harmonic currents into the system, which can further increase transformer losses and exacerbate thermal aging. To mitigate these effects, utilities must carefully assess the impact of EV adoption on their distribution networks, upgrade transformers as needed, and implement strategies like managed charging to shift EV charging to off-peak hours. Advanced monitoring and thermal modeling can help to optimize transformer loading and extend their lifespan.