A novel capacity allocation method for hybrid energy storage system for electric ship considering life cycle cost

Abstract

Under the trend of promoting the development of green ships, electric ship technology has emerged as a popular research field. Electric ships, primarily powered by diesel generator sets (DGs), continue to consume a large amount of fossil energy, and the unstable output of DGs can further increase emissions of pollutants. The addition of a hybrid energy storage system (HESS) has emerged as a better solution. However, this approach may increase initial investment and maintenance costs, and pose greater challenges in energy management. In response to the complex design problems of HESS in ship operation and the strong coupling between capacity allocation and power allocation, a method for HESS capacity optimization that considers joint optimization of power allocation and capacity allocation has been designed. In this method, the rain flow counting technique is utilized to estimate the equivalent charging and discharging times of lithium batteries, aiming to optimize the fully life cycle cost (LCC) of HESS. Additionally, to ensure efficient operation under various working conditions, a strategy for power allocation based on working condition segmentation and empirical mode decomposition (EMD) is proposed, with the model being solved through gray wolf optimizer (GWO) algorithms to determine the energy storage configuration scheme and the output power of each device. Finally, multiple HESS capacity configuration schemes have been designed to verify the superiority of the configuration method outlined in this paper.