Optimal Energy Management of FC-Battery Shipboard Power System using Dynamic Programming

The move towards more sustainable shipping has increased interest in using fuel cell-battery hybrid power systems. The sector still lacks know-how on the optimal energy management in such a design. Two key performance indices are the fuel consumption and FC degradation, which are conflicting objectives for the optimization. Offline optimization of energy management with a known power profile is a useful tool for determining control approaches and providing a benchmark for the performance of real-time control implementations. This work solves the optimization problem of the power split between fuel cells and energy storage systems by quantizing the timestate space and finding the optimal trajectory via dynamic programming. The optimization additionally allows for the on-off switching of fuel cell modules as an additional degree of freedom in the presence of multiple fuel cell modules integrated into the shipboard power system. The optimal trajectories for multiple FC modules and the ESS are computed for a given load profile. Results indicate that the FC degradation can be significantly reduced by optimizing the timing of on- and off-switching. The selective switching of modules further increases the widens the Pareto-optimal front curve's span of optimal combinations of fuel consumption and FC degradation.