Abstract

The increasing adoption of Vehicle-to-Grid (V2G) technology enables electric vehicles to operate as mobile inverter-based energy resources, fundamentally altering their interaction with distribution networks. While the power quality impacts of unidirectional electric vehicle charging have been widely studied, bidirectional operation introduces distinct challenges associated with grid synchronization, DC injection, harmonic emissions, and large-scale aggregation. This paper examines the power quality (PQ) characteristics of V2G-enabled electric vehicles, with emphasis on differences between charging and discharging modes. Particular attention is given to synchronization dynamics, asymmetries in converter operation, and system-level effects arising from the simultaneous discharging of multiple vehicles. The analysis highlights that V2G operation cannot be treated as a simple reversal of charging behavior and underscores the need for dedicated PQ assessment frameworks to support large-scale deployment.