The necessity of time-based calculations for dimensioning of hybrid power supply systems of ships within the early design stage

Abstract

While hybrid ship drive systems may offer a large potential, a thorough analysis is needed as it is strongly dependent on the operational profile. The fixing of costs during the early design stage, leads to the necessity of a precise evaluation of the systems efficiency within this phase. Conducting statistic-based calculations can be inadequate due to the time-dependent behavior of the battery. Moreover, idealized temporal data is often utilized for the design of battery supported ships. Therefore, this paper discusses the consequential inaccuracies using statistical or smoothed data. But also examines the potential of an advanced in-house developed statistical approach. For the examination, an internal developed method for dimensioning hybrid ship power systems is used. The paper shows that conducting statistical calculations lead to incorrect modeling of battery behavior, while smoothed power time-series can result in an overestimation of the battery lifetime (up to 21% less charge cycles).