Power management and optimization of marine hybrid propulsion systems: A combinator surface methodology
Fan Gao, Astrid H. Brodtkorb, Mehdi Zadeh, Sigrid Marie Mo
Abstract
To promote fuel-efficient and safe marine propulsion, hybrid power and propulsion systems are proven to be a promising alternative to conventional mechanical propulsions. This paper proposes an optimization framework for the power management of hybrid propulsion systems based on a novel combinator surface approach, which enables the most fuel-efficient operation with safety considerations against overloading and propeller cavitation . Four ship operational modes including mechanical propulsion, Power Take-in (PTI), Power Take-off (PTO), and Boost mode are comprehensively considered. The developed optimal power management presents significant efficiency advantages, reliability, and flexibility compared to the conventional method such as the combinator curve. It also enables comparisons of propulsion efficiency, cavitation, and overloading risks among different operational modes. Moreover, the proposed controller facilitates the intuitive design of acceleration paths by a trade-off between fuel efficiency and acceleration time. For validation and benchmarking, a real operation case study is performed on a line-fishing vessel equipped with a controllable-pitch propeller (CPP). The results show that the PTO mode is not always beneficial compared to mechanical propulsion, and the gear ratio selection plays an important role in determining propulsion fuel efficiency and operation safety. Also, the acceleration path that reduces the acceleration time results in increased fuel consumption.