A multi-objective optimal power management strategy for enhancement of battery and propellers lifespan in all-electric ships

Abstract

This paper proposes a multi-objective optimum approach for the participation of the propulsion system in mitigating the All-Electric Ship (AES) power system fluctuations. This strategy optimally balances the propellers torque/speed change and the energy storages charge/discharge rate to obtain an economically-efficient operating point. The method aims to minimize the propeller mechanical fatigue and the battery loss of life (LoL) according to their investment costs, while other operational constraints are considered. For this purpose, a novel index, called the Propulsion System Cooperation Coefficient (PSCC), is developed. This index adjusts the magnitude of the propeller speed/torque variations regarding the AES investment costs, components LoL, and power quality. A straightforward procedure is proposed to acquire this coefficient during an operating condition. The simulations revealed that the proposed multidisciplinary approach remarkably reduces the AES operation and maintenance expenditures associated with the loss of life of the mechanical and electrical equipment. This outcome holds with the vessel being either operational or at the design level. Since the proposed strategy demonstrated that addressing mechanical fatigue damage is significant in a demand-side control approach, it can also benefit the terrestrial microgrids power management systems.