Harmonic-free Energy
Propulsions on Seili Controlled by
Vacon´s Liquid-cooled Drives
Since March 2004, m/s Seili has been sailing again in the Gulf of Finland, powered with Vacon liquid-cooled main
propulsion drives which save space and energy
he rebuilt rear of the vessel provides room for two propulsion
systems instead of one as earlier. This improves vessel movement and guarantees sufficient power needed for towing and winter navigation, irrespective of ice conditions.
The main propulsion on the m/s Seili
is controlled by Vacon’s liquid-cooled drives
with a total power of 2.3 MW. Six Vacon
NXP drives are controlling the steering gear,
and two regenerative liquid-cooled NXP
drives are controlling the main propulsion
equipment. The new dynamic positioning
system allows m/s Seili to keep its position
automatically without anchoring.
The owner, the Finnish Maritime Administration, chose Vacon’s regenerative liquid-cooled drives as they require only small
space for assembly and no additional filters
are needed onboard to approve power quality. In Vacon drives, harmonic voltage distortion with full load has been under 2%.Thus,
it is clearly below the general level of 5%.
The Vacon regenerative drive has
been developed especially for applications
requiring continuous braking. The regenerative drive produces practically harmonicfree energy that can be fed back into the
supply. It also actively compensates the supply’s power factor.
T
Generator power
close to converter power
Onboard m/s Seili, three 820 kVA Catepillar generators produce a total of 2460 kVA.
As the converter load has a power factor
42 SEATEC 2005
close to 1, the continuous generator power is approximately 2400 kW.The two propulsion drives have a power of 1100 kW
each, and the steering gears include six
drives in total with a power of 15 kW each.
Two of the steering gear drives are
continuously running hydraulic oil pumps
and the other four are running the steering gears. The hotel load is approximately
150 kW.
At a crash stop, the propulsion drives
will hit the current limit and consume a total
of 2 x 1100 kW; steering gears are at full
load (90 kW) and the lights are flickering.
This is not surprising, as the propulsion,
steering and hotel load reach the amount
of the total available generator power.
The use of frequency conver ters
would normally cause problems in harmon-
ics and EMC issues.To avoid building a separate clean power net for 400 V, it was decided that a 690 V/400 V transformer would
be used instead. This would only be possible if the harmonic content of the 690 V
net was low because sensitive navigation
equipment, among others, will not otherwise work properly.Thanks to Vacon’s regenerative drive technology, the power
factor is ~1, harmonic voltage distortion
is below 2% and current distor tion is
about 3%.
As seen also [