Lab. EPGC

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.

The adoption of innovative distribution systems on ships (such as the Direct Current distribution) is hampered by the current lack of standards for the calculation of fault currents in DC distribution systems with nominal voltage greater than 1kV. Furthermore, unlike what happens in AC distribution systems, the extreme variability (in terms of generation and conversion systems) in the possible DC current production methods onboard ships makes it extremely difficult to define simplified formulas for the fault currents calculation.

For these reasons, a research activity it is in progress, aimed at determining the short circuit currents on board ship in DC systems with rated voltage above 1kV (defined MVDC distribution - Medium Voltage Direct Current distribution).

In the very last years, the High Voltage Shore Connection (HVSC) has represented one of the best technical solutions to supply ships at berth without operating shipboard prime movers, thus reducing air pollution in city ports. Taking into account the potentiality of this technology, on one hand it is possible to notice the interest of several city ports throughout the world, on the other also the shipyards have started to design shipboard power systems capable of supplying ships at berth. Considering a single ship, the requested power may be about 10 MW in order to keep certain services running during berthing.

Nowadays, the Medium Voltage Direct Current (MVDC) distribution represents an interesting possibility for improving the future shipboard power systems. The concept is based on the widespread use of power electronics equipment, in order to interface generating systems and loads to the MVDC bus (rated voltage higher than 1 kV). This technology is able to provide several advantages, among others easy integration of storage systems and reduction of the power system’s weight/volume. On the other hand, it is important to highlight the need of a proper voltage control system, even more in presence of tightly controlled load converters. Indeed, the contemporaneous presence of high bandwidth controlled converters and filtering stages (RLC filters) may determine dangerous voltage oscillations and instability after a load connection.

Title

Naval Smart Grid (NaSG) - Integrated Power System for All Electric Naval Vessels with control and reliability characteristics - research project PNRM (National Research Military)

Period

March 2013 - December 2015 (in progress)

Client

NAVARM (Directorate of General Naval Armament) - Italian Navy

Leader

University of Trieste – Lab. EPGC.

Other partners

Sapienza - University of Rome
Polytechnic of Milan.

Title

Advanced Control Method for Robust Stability of MVDC Systems - research project ONR (Office of Naval Research - Global Office, London UK)

Period

October 2011 - July 2013

Client

ONR (US Navy Office of Naval Research) - Global Office, London UK

Leader

RWTH Aachen University - Institute for Automation of Complex Power Systems

Other partners

University of Trieste – Lab. EPGC

Title

MVDC Large Ship – Medium Voltage DC integrated power system for Large electrically propelled Ships - research project POR-FESR

Period

October 2010 - January 2014

Client

Regione Autonoma Friuli Venezia Giulia

Leader

Fincantieri SpA

Other partners

University of Trieste (Scientific lead) – Lab. EPGC
Polytechnic of Milan
University of Udine
Blu Electra SRL
Area Science Park
RINAVE consortium