Power Management Strategies Based on Propellers Speed Control in Waves for Mitigating Power Fluctuations of Ships

Abstract

This paper proposes two novel Power ManagementStrategies (PMS) to enhance the electrical power quality in twinscrew All-Electric Ships (AES) during vessel-wave encountering. Soothing PMS (SPMS) focuses on mitigating power fluctuations of the propulsion system since it has significant impacts on the power system in extreme conditions. For this purpose, the PMS modifies propellers speed based on the in-and-out-of-water effect Loss Factor (LF) in wave collisions. This method does not require typical equipment, such as Energy Storage Systems (ESS), to moderate the variations. Hence, it decreases the ESS demand capacity and maintenance costs at the design and operation levels. An integrated ship model is introduced to determine this loss factor in waves thoroughly. Furthermore, due to the propeller dynamics in speed altering, an adaptive delay is embedded in SPMS to improve its efficiency, and an Advanced Soothing PMS (ASPMS) is developed. To determine this varying adaptive delay during an operation, a straightforward algorithm is proposed that does not impose the PMS to compute complex differential equations. Simulations reveal that both PMSs soothe the propulsion system power fluctuations and remarkably reduce the power system frequency and voltage variations. Meanwhile, the ASPMS surpasses the SPMS in terms of improving the power quality.

Hierarchical robust shipboard hybrid energy storage sizing with three‐layer power allocation

“…[9], FC has been viewed as one of the key technologies for the future green ships. However, different from the land-based transportation, such as electric vehicles or railway, ships suffer from very uncertain marine environment, resulting in large variations on propulsion power and causing voltage sags in direct current (DC) bus [10,11], which deviates the operating pattern of FC since FC tends to keep a constant power output. In this sense, the harsh marine navigation environment has raised concerns on the operating flexibility of AESs [12].…”

Implementation of Ship Hybridisation: Sizing a Hybrid Crew Transfer Vessel Considering Uncertainties

“…Traditional optimization techniques that ignore uncertainty result in over-optimized, unrealistic designs that are not robust. The required error margin that develops during the design process can be minimized if these uncertainties and their impacts are promptly captured (Priftis et al, 2020;Nasiri et al, 2022b).…”