Control scheme of voltage sag compensator using bi-directional DC/DC converter of double-layer capacitor

A novel voltage sag compensator with bi-directional DC/DC converter of double-layer capacitor is proposed. Recently, the double-layer capacitor which has drawn attention as a new energy storage element has a lot of advantage such as no maintenance, long lifetime, and quick charge/discharge characteristics with large current. This capacitor is attached to the DC link of voltage sag compensator system through the high-efficiency DC/DC converter in order to compensate the DC link voltage drop during short-term power interruption as voltage sags. This DC/DC converter is used to control the charging current to the double-layer capacitor and also used to keep the DC link voltage constant for discharge of the double-layer capacitor. Therefore, the proposed DC/DC converter has the high-efficiency controller, dynamic compensator of voltage sag is driven by this converter. Finally, simulation and experimental results show the validity of the control scheme and the ability of the voltage compensator.