Experimental 400 kW sec double-layer capacitor energy storage system

Double-layer power capacitors (DLCs) are very attractive in several applications and specially in high power load shaving. However, the electrical behaviour of these devices is considerably different from the traditional capacitors. Due to the low voltage of the single cell DLC, many devices have to be connected in series to reach the technically required voltages. This paper presents the aspects to be considered in building an energy storage system based on double-layer capacitors, especially those factors that may affect the voltage sharing among capacitors. Furthermore, the paper presents the experimental results from a 400 kW sec energy storage system built with 100 double-layer capacitors connected in series