MVDC Large Ship project

Medium voltage dc integrated power system for large all-electric ships

MVDC Large Ship is a research project aimed at analyzing the implementation of a medium voltage DC integrated power system for large electrically propelled ships.

The aim of the study is to lay the technical/scientific foundations for the evaluation, definition and design of a medium voltage DC integrated power system.

Three main subsystems were studied during the project, i.e. generation, distribution and utilization.

With regard to the medium voltage direct current, each subsystem was investigated starting from an in-depth analysis of the state of the art.

An integration of these different subsystems was then performed, considering a hypothetical cruise liner case study.

This activity highlighted the advantages and drawbacks. In particular, the introduction of direct current has the following “pros”:

• Reduction of power station technical rooms, by using compact high-speed generators for power generation. 
• Enhancement of electrical grid dynamic behaviour during sudden power demand, achieving a better voltage control using controlled power converters and storage systems. 
• Improvement of the network quality of service and fault tolerance, as the DC grid is independent of frequency, and is assisted by storage systems. 
• Enhancement of power control in different modes of operation, by exploiting the DC distribution power converters to feed the variable-speed motors. 

The MVDC Large Ship project also highlighted interesting results related to:

• Voltage control. In this regard, new and promising control techniques have been developed to freely utilize standard power converters (the cheapest solution) to feed the shipboard loads. 
• Knowledge of DC transient phenomena (e.g. short circuit ), allowing an informed and appropriate  approach to designing the DC electrical grid. 
• Power system dependability analysis, by exploiting new techniques to verify the system’s robustness to faults (in both AC and DC systems). 

The MVDC power system is a new application, and therefore the components necessary for the realization of an integrated power are not always available. From a technological point of view, remarkable advances have been made, but the research and development of new solutions must continue.

The research activity in Friuli Venezia Giulia (a region with a high percentage of researchers) has helped to improve local naval expertise, as new collaborations have been established between research institutions and companies. It has thus  created new jobs for young talents in a strategic field for the future of naval  transportation.