Ultracapacitor-based storage: Modelling, power conversion and energy considerations

Ultracapacitors are becoming a very interesting solution to store electrical energy due to their high efficiency, robustness, simplicity and their increasing energy density. Furthermore, the high power density they exhibit can be considered their main advantage when compared to batteries. Nevertheless, their dynamic behavior and the way energy is stored differs from conventional capacitors. A comprehensive study of the existing differences is presented in this paper, in order to take them into consideration in the design and control of ultracapacitor-based energy storage systems.