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For the trade press
Innovative solution from Siemens increases reliability of the power supply for
offshore drilling platform drive units
Erlangen, 2008-01-21
As part of a general overhaul, Siemens Energy has equipped two drilling
platforms owned by Transocean of Houston, Texas, the largest offshore drilling
company in the world, with a reliable, high availability power supply. The new
system based on the direct current network link Siplink replaces the former
power supply for the drilling platform drive units. The Siemens solution not only
increases the reliability and availability of the drive units but also offers savings
of up to a third of the fuel costs for the diesel generators accompanied by a
reduction in CO2 emissions. Generator maintenance costs can also be cut
because the generators can run at a considerably more effective operating point
controlled via a fail-safe energy bus.
Offshore drilling platforms and drilling ships need a reliable power supply for their drive
units. In order to fulfill their function, drilling platforms have to be able to be maneuvered
exactly in position, with their up to eight thruster motors, not only against the wind and
wave action but also against the torque of the drilling drive unit. If the electric power
supply were to fail there would be a risk of the drill pipe breaking within a very short
time, causing repairs costs amounting to millions. The offshore drilling company
commissioned Siemens to develop a new power supply system that would increase the
availability of the power supply system for the thruster drive units of Transocean’s
Sedco 702 and Sedco 706 drilling platforms and thus reduce operating costs.
Siemens developed a solution for the two drilling platforms based on Siplink (Siemens
Multifunctional Power Link), a flexible direct current (DC) network link in which two
converters are interconnected by a DC link and are each connected to two independent
power networks. In this way Siplink connects the two 11-kV medium voltage
subnetworks on board the drilling platforms via the DC link. If a fault occurs in one of the
two subnetworks, the DC link ensures that the drive units are supplied with power from
the other 11-kV subnetwork. The power requirement of both medium voltage
subnetworks is measured continuously in all operating states and the load flow is
automatically optimized. A fail safe energy bus (FSE) performs this function for each DC
subnetwork.
If a fault occurred in the previous power supply system for the thruster drive units, all the
drive units supplied by the 11-kV subnetwork concerned failed. Because of the high
inrush currents in the converters, the motors could not be switched back on
simultaneously but only in sequence, which could lead to the drilling platform drifting off
position if this took too long. With the new system thanks to control via FSE bus all drive
units remain in operation even if one of the two 11-kV subnetworks should fail.
The power supply solution for the drive units using Siplink also allows substantial fuel
savings accompanied by lower CO2 emissions. Up to 30 percent of fuel costs can be
saved because the diesel generators which feed power into both networks can now be
run at a considerably more effective operating point. This means that one diesel
generator in each subnetwork is sufficient in a calm sea, whereas in the past two always
ran in parallel. The other generators are only switched in when the sea is rough or in
case of higher requirements. Formerly three diesel generators in each subnetwork used
to supply power to the thruster motors. Two generators always had to be run
simultaneously to provide a fail-safe supply even if their output was not needed at that
particular moment. Last but not least, the Siplink solution cuts maintenance costs for the
diesel generators because they can run at a significantly more favorable operating
point, and not as before in the lower partial load range where they are subject to high
wear.
The Siemens Energy Sector is the world’s leading supplier of a complete spectrum of products, services
and solutions for the generation, transmission and distribution of power and for the extraction, conversion
and transport of oil and gas. In fiscal 2007 (ended September 30, based on IFRS), the Energy Sector had
revenues of approximately EUR20 billion and received new orders totaling around EUR28 billion and
posted a profit of EUR1.8 billion. The Energy Sector had a work force of 73,500 at the beginning of fiscal
2008.
Further information is available at:
 www.siemens.com/energy
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All figures represent the sum of the nonconsolidated figures for the
Power Generation and Power Transmission and Distribution Groups and for
the Oil, Gas and Marine Solutions Division of the Industrial Solutions
and Services Group.
Download this and other press information:
www.siemens.com/ptd-press |
| Reference number: EPD200801.003 e |
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