In the ships endowed with electric propulsion (namely AESs - All Electric Ships), the power system is essential and vital, because all the onboard loads are powered by it. However, in case of ships in which a black-out is extremely harmful (due to economic and environmental reasons, in case of offshore Oil&Gas applications, or due to the failure of the mission, in the case of naval vessels) it assumes a major role. Therefore, for such vessels the main design goals for the Integrated Power System (IPS) are: ensure the required power quality, defined as quality of the electric power supplied to the ship's loads; ensure a high continuity of service, intended as the possibility to keep the ship in operation as much as possible. Because of the vital role that the IPS has in AESs, the above-mentioned objectives are closely related to all the other possible objectives of the project, such as performance, efficiency, safety, maintainability, and environment protection.

In the past, the achievement of these objectives was widely based on the designers’ skill. Nowadays, it is possible to apply several advanced techniques already during design phase, to help comply with requirements. These techniques can be borrowed from other fields in which requirements that are more stringent are common (e.g. aerospace engineering). These techniques belong to the “dependability” theory. The main concept underpinning this theory is the "service", defined as the set of operations performed by the system on behalf of its users. A “dependable” system is able to provide the "correct service" (or even one degraded but acceptable) in favor of its users, despite internal damaging events ("faults" and "failures"), within certain reasonable limits.

Thanks to the concepts and techniques contained in the dependability theory, the evaluation of the system behavior in case of damaging events can be integrated in the design process. The new design process becomes capable of reaching more effectively the objective to provide a system capable of being: resilient, as it provides a service acceptable even in case of failures; flexible, because it is able to adapt to different conditions of service; safe, as the decrease of black-outs reduces the risks; better performing, due to the increasing in productivity; efficient, through the optimization of system structure.

In this context, the research activity focuses on the application of the dependability techniques to marine power systems. In particular, the application concerns both the study of design methodologies in itself, and the study of shipboard power systems architecture through the dependability theory techniques.

More info: prof. Giorgio Sulligoi