Assessment of Power Quality Impacts and Integration Limits of Electric Vehicle on AC Charging: A Case Study of Thailand’s Urban Distribution System

In 2025, total EV sales exceeded 100,000 units, representing a 930.9% increase compared to the 9,700 units sold in 2022. This growth has led to a significant rise in the installation of AC normal chargers at residential locations. This paper focuses on assessing the power quality impacts related to harmonic, unbalance, and voltage magnitude resulting from the connection of AC normal chargers. Simulations were conducted using an industry-grade commercial power system analysis and simulation platform, modeling a typical LV network in Thailand’s urban distribution system and the data of on-board charger (OBC) in this paper was measured from measurement data at EV charging station to accurately represent the charging behavior. In the worst-case scenario results, the permissible level of AC normal charger should not exceed 47% of the rated transformer to keep Total Harmonic Distortion (THDV) within planning levels. The maximum allowable power difference of each phase should not exceed 7 kW to maintain a voltage unbalance factor in accordance with LV unbalance factor planning level. Additionally, based on the peak load scenario, the permissible level of EV charging should not exceed 10% of the rated transformer to keep standard service. The results of this study ultimately aims to provide guidelines on the maximum permissible integration of AC normal chargers to ensure compliance with power quality standards of utility. The results will be incorporated into the utility’s upcoming EV integration regulations.