The impact of high penetration of Renewable Energy Source (RES) and the decoupled power-frequency relationship raise the concern for RES participating in the grid frequency regulation. Energy Storage System (ESS) has shown its potential in power system with RES. This paper proposes a new control method of ESS considering the ancillary service efficiency and economical aspects. The proposed state of charge (SoC) feedback control is based on net-zero concept of frequency regulation model. A feedback gain is introduced to satisfy the grid regulations and economical index. The proposed control method is investigated over fractional frequency wind power system, which uses low frequency transmission lines or grids to transmit wind power. Simulations are done in Python and MATLAB/Simulink. The simulation results verify the effectiveness of proposed coordinate control strategy.