Control and Optimization of Electric Ship Propulsion Systems with Hybrid Energy Storage

Abstract:

Electric ships experience large propulsion-load fluctuations on their drive shaft due to
encountered waves and the rotational motion of the propeller, affecting the reliability of the
shipboard power network and causing wear and tear.

This dissertation explores new solutions to address these fluctuations by integrating a hybrid
energy storage system (HESS) and developing energy management strategies (EMS). Advanced
electric propulsion drive concepts are developed to improve energy efficiency, performance
and system reliability by integrating HESS, developing advanced control solutions and system
integration strategies, and creating tools (including models and testbed) for design and
optimization of hybrid electric drive systems.

The feasibility and effectiveness of HESS are investigated and analyzed. Two different HESS
configurations, namely battery/ultra-capacitor and battery/flywheel, are studied and analyzed
to provide insights into the advantages and limitations of each configuration. The trade-off
between control simplicity, modularity and overall system performance is evaluated and
analyzed. A MPC based-EMS has been implemented on a physical testbed. Compared to the
filter-based EMS, the proposed approach achieves superior performance, in terms of the
enhanced system reliability, improved HESS efficiency, long self-sustained time, and extended
battery life.