Page 29 - Industrial Plants

2650 kW @ 2.000 rpm, the PEM provides a boost to
the diesel at max power/speed, as shown in fig.6.
The PEM is capable of delivering 500 kW and it is
connected in parallel to the diesel by means of the
reduction gear. So, a max propulsion power of 2750 kW
is met up to 2000 rpm, combining the 2250 kW of the
diesel engine and the 500 kW of the PEM. A margin of
100kW is kept over the expected max
propeller power. The base speed of the PEM is set at
1000 rpm where the 500 kW (the rated power) is
given. Over 1000 rpm the PEM works in a constant
power mode up to 2.000 rpm.
From zero speed up to 1000 rpm the propulsion can be
provided by the PEM only. The electrical propulsion
lasts as long as the battery charge remains over a
certain value. During the transit the PMS
monitors the SoC of the battery in real time and when
the SoC goes too low the PMS switches on the diesel. diesel again and making the PEM provide the power for Fig. 6- Diesel and
The latter provides either the propulsion power or the the remaining transit time. At the end of the cycle the propeller power
energy for recharging the battery before the working battery has lost part of its charge again. In order to vs. speed. The transit
area is reached by the tug. The fig. 5 shows the cycle restore the full SoC the auxiliary generator is switched speeds and powers
are shown.
described. on. This generator is rated 150 kVA. The tug is in idle
Considering the energy required by the PEM in the and its power need is quite low so the auxiliary
working mode, the battery must provide approx. for 30 generator con deliver about 70% of its power to the
minutes 230 kWh with a 60% of discharge. If so, battery.
the battery pack should be rated 380 kWh @ 2C with a
minimum safety margin in SoC and energy. The battery
has the same 2C rating either for charging or Conclusion
discharging. The paper shows some basic consideration for an
When the working mode has ended, the tug begins hybrid system for vessels that work in a wide variable
another transit. During the first part of the transit the power range. The integration of a PEM in parallel to the
diesel provides either the propulsion power or the energy main diesel helps in reducing the fuel consumption
for recharging the battery, as infig. 5. When the battery and improves the response time of the propulsion
is fully charged the PMS can switch off the system when in maneuvering.

Giordano Torri

Giordano Torri was born in 1953. Degree in Electronic products for the static conversion of the electric energy
Telecom Engineering at Pavia University, 1977. At and for the electric power drive systems in industrial,
present, Chief Technology Officer at Fincantieri SI. In the transportation, energy production and energy
past he covered the role of R&D and Engineering distribution fields. Recently he was responsible for
director at Ansaldo Sistemi Industriali. He devoted projects for Smart Micro Grid, Energy Storage,
most of his activity to the development of solutions and Renewable Energy and Hybrid Propulsion Systems.

IndustrIal Plants - May 2017
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