Bidirectional EV Charging for Frequency and Voltage Support in Smart Grids

Abstract

The rapid growth of electric vehicles (EVs) is changing the electrical characteristics of distribution networks. Conventional charging mainly draws energy from the grid, whereas bidirectional charging enables controlled power transfer in both directions between an EV battery and the grid. This work investigates Vehicle-to-Grid (V2G) and Grid-to-Vehicle (G2V) operation as flexible resources for frequency regulation and voltage support in smart grids. The proposed framework combines a bidirectional power converter, battery state-of-charge monitoring, grid measurements, communication, and a supervisory energy-management controller. During periods of excess generation or low system frequency, suitable EVs can inject active power into the grid. During surplus generation or when charging is beneficial, the controller can increase G2V charging within user and battery constraints. Reactive-power control can also be coordinated to assist voltage regulation. The framework is intended to improve grid flexibility while maintaining EV mobility requirements, battery operating limits, and charging quality