Frequency Stability in Weak Grids Using Independent Electric Vehicle

Abstract

Electric vehicles (EV), connected to the power grid, serve as distributed load or energy storage. In weak power grids, integration of Electric vehicles as energy storage provides many services such as power quality improvement, effective power control, and frequency regulation. On the other hand, the EV plug-in/off to a weak grid as a distributed load can result in poor power quality issues such as unacceptable frequency deviation. In this paper, a proposed control/operation strategy is presented to improve the frequency stability of a weak grid connected to EVs. It is proposed to use the EV to improve the frequency deviation during the plugin EV as a distributed load (charging mode) and/or as a storage device (discharging mode).Furthermore, a smart plug off strategy is proposed in order to disconnect the EV from the weak grid without frequency interruption. The proposed system is simulated in Matlab environment and a comparison between the system with and without the proposed Electric vehicles control schemes under different operating conditions is presented. Results prove the effectiveness of the proposed control/operation strategy.