This paper proposes a V2G operation method of EV to be able to perform frequency regulation, EV charging, and SOC management. This method exhibits the multifunctionality in regard to instantaneous discharging EVs during the charging against frequency drop; primary driving and power grid ancillary services for example, frequency stabilization by simultaneously managing the desired state of charge (SOC) of the batteries. Hence, it can bring the benefits in stabilizing grid frequency under high penetration of renewable energy. We also develop the mathematical models based on characteristics of the proposed EV charging method for analysis and design. The outcomes indicate charging/charged EV can participate in frequency regulation so that EV demand adjustment helps embrace renewable energy variation and stabilize the power system. The feasibility of this method is verified for a real power grid model to demonstrate efficacy of EV charging control for SOC management using DIgSILENT/PowerFactory.