Design and analysis of a sliding-mode power electronic controlled battery / supercapacitor hybrid energy storage system for remote wind power

This paper presents the design of a lead acid battery / supercapacitor hybrid energy-storage device designed to store intermittent renewable power while at the same time ensuring the battery is charged according to an appropriate regime and protected from overcharge. The modeling technique for the battery impedance at float charge level and the parameter extraction method are described. Power to and from the supercapacitor is controlled by a bidirectional synchronousbuck DC-to-DC converter. A sliding mode control system specific to this application, is developed which is employed to hold the battery voltage at a suitable charge level in the presence of an intermittent disturbance current by charging / discharging the supercapacitor. The performance of the converter, control system and energy storage devices is demonstrated at realistic operating levels by experiment in the context of a remote wind-powered battery-charging system.