Rule-Based Power Management Strategy for Hybrid Energy Storage Systems in Electrified Waterborne Transport

The increasing demand for environmentally friendly transport solutions has encouraged the development of hybrid energy storage systems for electric ships, combining batteries and supercapacitors to enhance efficiency and reduce environmental impact. Traditional battery-only systems face challenges of accelerated degradation due to current peaks, leading to the need of overdesigning the capacity and reducing the maximum discharging rate. Supercapacitors have high power capabilities with limited degradation and can mitigate the ageing issues of batteries. This paper focuses on optimising power loss and increasing the supercapacitor utilisation per cycle in a battery-supercapacitor system for electrified waterborne transport. This study explores energy management strategies based on a curve-fitting algorithm to optimise the power distribution between the battery and the supercapacitor, and compares them with the standard low-frequency power splitting approach. The proposed method aims to reduce peak power stress on the battery, minimise energy losses, and extend battery life. Simulation results demonstrate that the cubic curve-fitting method outperforms other strategies, significantly reducing battery peak power and maximising the utilisation of supercapacitors. The findings suggest that, in the case of an electric ferry, the proposed hybrid configuration can achieve a 20% reduction in battery size while maintaining efficient energy management, making it a viable solution for future electric applications.