Enhanced Aging Model for Supercapacitors Taking Into Account Power Cycling: Application to the Sizing of an Energy Storage System in a Direct Wave Energy Converter

This paper proposes an original model for supercapacitors that takes into account both calendar aging and cycling aging. A state variable is used to quantify the state of aging. This model is based on a series of recent experiments conducted in various research laboratories on the same technology (Maxwell Technology) and serves to represent the degradation of equivalent series resistance and capacitance. This model is particularly useful in an aging-aware life-cycle cost analysis. We show that an accurate aging model is critical to the design of an energy storage system that optimizes the economic life-cycle cost. Such an optimization is particularly applicable for smoothing in offshore systems such as direct wave energy converters, which require both cost reduction and high reliability. The influence of an aging model in the sizing process is investigated toward the end of this paper.