Optimization of supercapacitor sizing for high-fluctuating power applications by means of an internal-voltage-based method

The latest advances in the field of supercapacitors (SCs) have made them a feasible alternative to be used in hybrid, energy storage systems. Sizing SCs in such systems is not obvious, especially in the case of banks comprising several series-parallel configurations. In this paper, a new algorithm for sizing a SC bank in high fluctuating power demand applications is proposed. The algorithm utilizes the expected discharge power profile, usually obtained from measurement campaigns, and a set of resistance (R) and capacitance (C) values of the equivalent circuit of the SC, which are provided by the manufacturer. Instead of yielding specific values for R and C, the method determines the RC limit curve which identifies the area of the RC-plane where the range of acceptable solutions can be found for a particular application. Thus, the internal resistance can be easily included in the design process. The validity of different cell combinations, including those not regarding each series-connected element as a sole cell, can be directly checked with this method, enabling the selection of the most suitable solution from an economic point of view.