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Modern Navies are facing a scenario in which the technology is changing at a fast pace, deeply affecting the expected missions their ships have to cope with. Not only new weapon systems and sensors, but also new subsystems and new threats call for the design of new ships. However, integrating these new elements into an existing ship is impossible, being it not designed to support them. Likewise, adapting an existing ship design is difficult as well, being the hull form not suited either for providing the required performance level or for accommodating the increased payload. Therefore, to face the actual evolutionary trend in naval ships, a new design strategy has to be adopted. In this paper, a multi-attribute design making approach to the concept design is depicted, able to exploit the capabilities of modern Information Technology tools. As an application example, a first simplified run of the process is shown, regarding the design of a multirole destroyer.

In this paper a conservative approach to build a Power Electronic Power Distribution System (PEPDS) has been used, introducing into an existing islanded AC system a Static Converter Interfaced Generator (SCIG). The paper tries to assess the power quality issues (in terms of v/f regulation) that can possibly arise when integrating conventional mechanical-based generators with new ones in an islanded power system, using a mathematical modelling approach. Two different phase regulators for the SCIG output voltage vector have been evaluated and compared, depending on the operative requirements of the SCIG prime mover (frequency regulation or fixed power injection). Finally, a set of simulations has been performed to assess the effect of the SCIG grid-side regulators parametric variations on the system's v/f regulation performance.

This paper presents the second phase of the Naval Smart Grid (NaSG) research project. In particular, it regards the study of an Integrated Power System (IPS) for an Italian Navy electric propelled ship, endowed with improved control and reliability characteristics. Aim of the project is to develop guidelines useful for designing a new ship, capable of exploiting innovative features: modular power system, subsystem’s flexible integration, improved efficiency, enable new weapon systems’ installation, improved survivability. In this regard, this paper presents the aims and the most significant technology research results of the NaSG project second phase.

This paper deals with the electromagnetic, mechanical, and cooling solutions for an innovative direct-drive suited for steering gears on board ships. The work is comprised in a research project funded by the Italian Navy. The research aims to realize a full-electric and oil-free drive for actuation of hydraulic loads in the perspective of “more green ships”. The electrical drive proposed is based on a fractional slot permanent magnet linear motor sized and optimized for high force and low speed operation, as required by hydraulic loads on board ships. The capabilities and efficiencies of the electric drive in servo-assistance to the hydraulic motor were evaluated in previous works of the same authors. In this paper the electrical, mechanical and thermal design and the feasibility of the installation are shown.

The naval vessels electrification is one of the most important issues to be tackled, because not only it allows a more efficient operation, but also is considered a technological game changer. Indeed, electrification offers improved operational benefits and enables mission systems continuous upgrade. Several technologies can be used, each presenting different impact on ship performance. Thus, instruments to analyze and compare different designs must be used already during early-stage design, allowing an aware and reasoned selection. In this paper, a Computer System Integrator (CSI) software is presented and an application example is given, about the electrification of a naval logistic support ship.

This paper deals with the mechanical solutions for installation of innovative direct-drives suited for steering gears onboard ships. The work is comprised in a research project commissioned by the Italian Navy. The research aims to realize a full-electric and oil-free drive for actuation of hydraulic loads in the perspective of more “green ships”. The electrical drives proposed are based on a fractional slot permanent magnet linear motor sized and optimized for high force and low speed operation, as required by hydraulic loads onboard ships. The capabilities and efficiencies of the electric drives in servo-assistance to the hydraulic motor were evaluated in previous works of the same authors. In this paper the mechanical analysis and the feasibility of the installation are shown.

This paper investigates the hydraulic system drive used onboard ships to actuate stabilizing fins. The hydraulic drives are often characterized by low efficiencies, heavy maintenance, frequent oil leaks and large weight and size. To overcome these draw-backs, in this paper a concept design of a full-scale permanent magnet linear synchronous motor directly coupled to the shipboard fin stabilizer, is presented, used as a servo-motor. The innovative electric drive is based on prototype of high thrust linear motor built in a previous research. A complete Simulink model, where electric, mechanical and hydraulic domains can be connected, has been realized. Simulations has been performed to evaluate the hydraulic drive efficiency and in order to assess the servo-assistance capabilities. The results show the feasibility of the proposed solution for a future practical application. This research has been carried out in the framework of the Italian Defence Research National Program for the development of ‘dual use’ technologies.

Alternatives to hydraulic drives used on board ship are under study for the Italian Navy in order to reduce the use of the oil which cause environmental problems and high cost. The hydraulic system drive used onboard ship are affected by low efficiencies and generally require intensive maintenance, very high encumbrance. So that the Italian Navy has commissioned a research project for the construction and installation of an innovative oil-free electric drive based on a permanent magnet linear actuator. The new electric motor is more efficient, fault-tolerant, reduces the encumbrance and ensures a greater control.

The increasingly presence of HVSC connection onboard ships opens the path for innovative applications, such as ship-to-shore connection. Indeed, it is possible to supply power to land during emergency (mainly to deployed camps/bases), thanks to the electric power generation capabilities of modern all electric ships. However, the use of the same system to provide both the HVSC and ship-to-shore connection functions require a careful assessment of the equipment to be installed both onboard and on land. To achieve that, ship-to-shore connection requires a shore side mobile substation, containing all the necessary equipment for the land power distribution, and a ship side substation, either implemented in shipboard power system or installable at need. To successfully implement such a system, an appropriate design of protection systems is required, assuring proper protection to equipment and people. Moreover, the capability of the ship-to-shore connection to supply an existing land power system implies a high rate of adaptability, and a careful assessment of the land power system's grounding and protections. The development of such technology will be relevant for military applications, but civilian application is possible and foreseen in future (dual-use technology). In this paper, an analysis of possible ship-to-shore connection configurations is made, together with considerations about protection of both the connection equipment and the supplied land power systems.

The increase in installed power onboard ships and the adoption of electric propulsion led to the need of a rather complex power system. The so-called Integrated Power System (IPS) feeds all the ship loads, integrating into a single entity the functions of generation, regulation, distribution and utilization of the electric power. The integration, thus being a powerful tool to increase vessel's performance, reliability and efficiency, permits also the propagation of disturbances to all the users fed by the IPS. Being Power Quality a primary need for the loads (and especially for some particular military ones) it is needed an assessment of the disturbances that can occur in the power system, both in terms of voltage and frequency transients and in terms of harmonic distortion. In this paper is presented a measurement campaign to assess disturbance levels and performance of a Naval vessel.

This contribution starts with a review of the state of the art of existing high-voltage shore connection (HVSC) systems in terms of principles, rules, publications, technologies, and relevant installations. Then, tutorial sections present the main technical aspects of HVSC systems as ship-to-shore interface, shore equipment (transformers, converters, etc.), onboard devices (cubicles, shore switchboard, etc.), operating sequences, and feasibility aspects, for both commercial and military applications. Finally, some technical challenges are presented, concerning intentional/unintentional bonding, interactions between HVSC bonding and cathodic protection systems, bonding opportunity, and electrical safety aspects related to bonding issues in case of large earth fault currents in port facilities.

The paper presents the Naval Smart Grid (NaSG) research project, concerning the study of an Integrated Power System (IPS) for Italian Navy All Electric Ships (AESs) with control and reliability characteristics. Aim of the research is to produce results useful for a new ship design, endowed with the following innovative features: modular power system; subsystem's flexible integration; efficiency improvement; security improvement; enable new weapon systems' installation; survivability improvement. The aims and the results of the research are here concisely presented, together with brief discussion of the significant technology research results.

Induction motors are presently the most widespread kind of electric machinery used in industrial and vehicle applications. In the engineering practice, it frequently happens that designers or final users have to roughly estimate the size, weight and some basic performance data of an induction motor based on few specification requirements such as its rated speed and power. This paper describes a heuristic approach which can help make a first-attempt dimensioning in an approximate but reliable way. The method uses homothety as the theoretical basis and derives practical laws by identifying homothetic law parameters through the statistical analysis of a set of sample built machines. The results obtained are compared to those derived from classical books showing significant discrepancies which fully justify the adoption of more sophisticated heuristic models as those being presented.

The new simulator of the FREMM (European Multi Mission Frigates) electric Integrated Power System (IPS) is treated in this paper. The simulator, recently delivered by the University of Trieste to the Italian Navy, is utilized to study relevant electromechanical transients of the on board IPS. In particular, this simulator is employed in verifying some automated sequences and restore maneuvers, which are hard to be analyzed through on board tests. Other uses will be the support in crew training and the study of different control strategies. The developed IPS simulator has shown to be a tool able to help navy engineers and electrical staff in understanding some relevant behaviors in electrical transients, permitting the simulation of the system in a cheap but accurate way. A validating campaign of the numerical results is now on the way, referring to commissioning and sea trials results of the first built ship of the class.

Italian Navy is being equipping its fleet with the new FREMM class of frigates, developed under a joint program by Italian and French Navies. They are conceptually new war ships endowed with a hybrid propulsion system, composed by a gas turbine and two electric drives, which can be operated also as shaft-generators. University of Trieste has been charged with developing a software simulator of the FREMM integrated electrical power system and its propulsion drives, which has been recently delivered. The simulator will be employed by Italian Navy for virtual tests and personnel training activities. The paper is focused on the shaft-generator operation of the electric propulsion drives and their simulation. Numeric results are displayed in the paper and compared with factory tests in order to validate the simulator.