Optimized current reference generation for system-level harmonic mitigation in a diesel-electric ship using non-linear model predictive control

Non-linear optimal control using collocation and multiple shooting is investigated in this paper to generate the current reference signal for the lower level control of an active filter in a marine vessel with diesel-electric propulsion. The optimization objective is aimed at using the active filter for system-level minimization of Total Harmonics Distortion with the minimum rating of the active filter. The investigation of the different algorithms is oriented to the search of a solution that can offer a good compromise between accuracy and real-time implementation abilities. Results indicate that linear problem formulations are more suitable for real time implementation as they require less computational costs with minimal loss of flexibility. Non-linear problem formulations provide higher flexibility at the cost of higher computational efforts.