Development And Application Approach of EV Impact And Mitigation Analysis Methods for Use In Traditional Rural Electric Utility Planning Practices

To reduce greenhouse emissions and pollution, the U.S. is witnessing a rapid growth of electric vehicle (EV) adoption. The increasing EV charging demand will be additional load to electric utility distribution systems, which may cause undervoltage and thermal overloading on circuits and transformers. Studying the potential impact of EV charging on distribution grid and coming up with methods and strategies to manage and overcome the challenges is critical to maintain the system reliability and available service capacity. This paper presents the results of a recent project on studying the impacts of potential EV growth on West Kentucky Rural Electric Cooperative Corporation, a rural electric distribution cooperative, circuits using different EV charging profiles using EPRI's DRIVE and OpenDSS tools. IEEE Standard C57.91-2011 and C57.110-2018 are utilized to study the thermal dynamics of transformers due to EV charging considering harmonics. This paper also studies the potential impact of newly DOE-proposed efficient transformer based on amorphous metal core on transformer temperature rise. An approach to integrate the analysis methods with daily, traditional utility distribution planning process using Milsoft's Windmil commercially available software to mitigate transformer temperature rise due to EV charging is also discussed. A method of using real time monitoring of transformer temperature for thermal model validation and optimal EV charging is proposed. This paper also presents an ambient-temperature-adjusted transformer rating method, and the technical aspects and economic benefits to utility retail residential rates brought about by the methods.