IEEE Electrification Magazine - December 2019 - 105

We are witnessing a
significant increase
in the failure rate of
shipboard propulsion
transformers due to
the introduction of
new propulsion
power electronics
devices.

controllable, power electronics-based
device with a high-frequency transformer ensuring galvanic insulation
between the MV and LV side. In addition, it may make available an LV dc
section at its secondary side. The SST
is a suitable device for shipboard
application since it is lighter and less
cumbersome compared with the traditional 60-Hz frequency transformer.
The onboard required power, furthermore, is rapidly increasing, as is the
space needed to arrange the components of the shipboard IPES. Moreover,
the required power increase leads to
several issues mostly related to the
rise in number and size of electronics
devices: the correct disposal of the heat load generated by
the electric devices, reliability and controllability of the
power system, electrical safety, power quality problems,
and increase in harmonic pollution.
Given this premise, it is obvious that it is possible to
evaluate all of the aforementioned issues only after the
functional design stage or once the IPES is fully defined.
However, in the functional stage design, it is not possible
to provide substantial changes to the IPES without significantly affecting the ship cost. Focusing on the highfrequency disturbance propagation issue, there is a need
to anticipate all possible information regarding the
power system design in previous stages to better evaluate the power system behavior in this new scenario pervaded by power electronic devices.
The cable length assessment [Figure 7(m)] is one of
the most important pieces of information to perform
harmonic pollution analyses. The higher the signal's frequency, the higher the impact of the cable length on the
possible rise of undesired resonances in the power

cables, according to the travelingwaves model. Therefore, these new
devices cannot be integrated as a
mere refitting in the existing IPES
but should be integrated in a better
and rational manner. New methods
and tools are required to lead the
innovation brought by these new
devices as well as to prove the concept of their onboard application.

Computer System Integrator
Methodology

Evaluating new technologies' impact
on grid power quality through simulations is not enough if there is no proof
of concept of the correct onboard installation, as stated in the previous section. Luckily, modern complex ships can be designed relying on computer
system integrator (CSI) software, thus allowing it to produce 3D parametric models (Figure 9) containing detailed
data about cable layout and their onboard paths. The current design procedure must be studied to investigate the
possible proposal of a new one that is capable of exploiting the above-mentioned technologies. The idea is to
apply the parametric capabilities offered by the new CSI
software to evaluate different systems' solutions in
terms of weight, volume, and cable length. The benefits
in the design process enabled by the integrated design
approach are even more important when the ship is electrically propelled.
For so-called all-electric ships, such a system approach
result is crucial for comparing different electrical distribution systems in terms of the whole ship's key performance
indicators (e.g., weight or volume). By applying the integrated ship design approach, the onboard power system
distribution can be selected based on objective and

Figure 9. A 3D parametric model of a military vessel highlighting the IPES with its distribution system cableways.

IEEE Elec trific ation Magazine / D EC EM BE R 2 0 1 9

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IEEE Electrification Magazine - December 2019

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