Mitigating distribution transformer lifetime degradation caused by grid-enabled vehicle (GEV) charging

Although 75% of the vehicle miles traveled in the US by 2040 could be electric, few studies have quantified their impact on the distribution network even at low GEV penetration levels. This paper presents a Monte Carlo simulation of transformer life degradation using a fundamental and harmonic transformer thermal model, historical distribution transformer load profiles, hourly temperature data, and surveyed vehicle data to determine transformer loss of life. A simple control strategy, based on transformer current, is proposed to mitigate lifetime degradation. Simulation results are presented for a fleet of distribution transformers in Phoenix, AZ and Seattle, WA under controlled and uncontrolled charging scenarios.