The paper is proposed total operation of a power conversion system for a Hybrid ESS. The system is formed with a photovoltaic energy system, ESS and system PCS to supply stable power. The conversion system utilized in the photovoltaic and ESS is formed with a parallel module in consideration of system characteristics. The paper describes the control method applied in the power conversion system and establishes the operation mode.

Most of the DC loads have had the sensitive characteristics electrically for input voltage. In this system, power converter is operated after connecting with DC loads to minimize the overshoot of the control voltage that may occur during connection of the loads. But whenever starting the power converter, parameters in circuit are different because power converter has been connected with diverse load types at each startup time. This is cause of a disadvantage to PI controller design of power converter. In this paper, the novel voltage control method using sliding mode control theory has proposed. This control method minimizes the overshoot of control voltage at startup of power converter. Despite the variations of the system parameters, the proposed voltage controller has fast response and robustness characteristics such as PI and sliding mode controllers. The proposed controller was applied to the three-phase AC/DC converter and each performance of controller was verified.