“ Feasible power electronics for demanding subsea applications“

A Research Project in process at SINTEF Energy Research Project periode: 2006 – 2010 Supported by The Research Council of Norway PETROMAKSprogramme

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Project partners and roles  SINTEF Energiforskning AS  Project responsible, executive and end-user of achieved competence

 NTNU, Dept. of Electric Power Engineering  Executive and guidance of the Ph.D. candidate

Financing and end-users of achieved project results:  The Research Council of Norway – Petromaks  HydroStatoil  TOTAL E&P NORGE  Petrobras Oil companies  EXPRO  SIEMENS Manufacturers  AkerSolutions

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Primary goal and intention

Pressure Tolerant Power Electronics

 Establish fundamental competence on new and pioneering concepts for realizing power electronic converters for subsea applications  Demonstrate the operability of critical power electronic components in high-pressure environments  Providing a basis for designing complete converters with pressurized power circuits The project is a conceptual study to build experience for future converter design SINTEF Energy Research

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Topside power electronics

Existing and planned installations with a topside frequency converter (2006) Project name Lufeng Troll Pilot Jubarte Mutineer-Exeter Ceiba Topacio Albacora Tordis IOR King Tyrihans Åsgard

Application Step-out length Depth Power Operated by Startup Boosting 900 m 333 m 5 × 400 kW Statoil 1998 Separation 3.5 km 340 m 2 MW Norsk Hydro 2001 Boosting/separation 4 km 1400 m 2 × 1MW Petrobras 2007 Boosting 3 - 7 km 160 m 2 × 1.1 MW Santos 2005 Boosting 7 km 750 m 2 × 1 MW Amerada Hess 2002 Boosting 8.5 km 495 m 2 × 840 kW ExxonMobil 2000 Seawater injection 9.5 km 370 m 1.5 MW Petrobras 2008 Separation 12 km 200 m 2 × 2.5 MW Statoil 2007 Boosting/pumping 29 km 1700 m 2.2 MW BP 2007 Seawater injection 35 km 300 m 2 × 3 MW Statoil 2009 Compression 47 km 250 m 2 × 8 MW Statoil 2012

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Subsea power electronics

 Some concepts (2006):   

SEPDIS - Framo/ABB Perfect Harmony for Ormen Lange - Siemens (Robicon) SPEED for Ormen Lange - Converteam

 All concepts based on one bar gas filled pressure vessels

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Weight considerations 1 bar versus pressure compensated (3000m) Assuming container for a 15MW subsea converter heat

1bar

3000m seawater

 Container for 1 bar internal pressure: 60000kg (wall thickness 100mm)  Thick steel walls  Need for complex cooling system

300 bar

heat

 Pressure compensated container 6000kg (wall thickness 10mm)  Thin steel walls  Possibility for conductive heat transfer through walls

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Expected advantages by exposing power circuit to ambient pressure  Weight and volume of containers significantly reduced  Electric power penetrators significantly reduced  reduced numbers of connections between pressure compensated

and 1 bar chambers

 Enables less complex and more reliable cooling system  e.g. direct conductive cooling, eliminating pumps, heat exchanger

Reduced cost and complexity &

Increased reliability SINTEF Energy Research

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Converter vital components Control pod in 1 bar environment

analog microcontroller control Converter Control

Sensors Interface voltage,current,temp,speed, etc...

External Control Bus

External control interface

Auxiliary Power Supply

Converter main control

1 6 Driver Interface

Auxiliary power

control/ status

power

Driver 1

Sensor interface

Galvanic Insulation

Driver interface

Driver 6

Power circuit in pressure compensated environment (e.g.300bar)

Gate drivers Power valves (IGBTs)

Dr1

Dr3

Dr5

Snubber circuits

DC - link

Output filter AC-link Dr2

Phase-leg module under test

Dr4

Dr6

Sensors DC-link capacitors Power busbars

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Test circuit for double pulse testing and Pressure chamber continuous switching

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Phase-leg modules is a building blocks for high power converters – Example: 690V 50Hz

1 bar pod

Circuit topology, voltage and power rating in the same range as the 300 bar test modules Siemens ”Perfect Harmony” 6.6kV,

0-200Hz, Induction Motor Drive SINTEF Energy Research

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Tyco converter PT module submerged in liquid DC-link capacitors: ICW SEG 100 µF/1100V Toroid current transformer for measuring pulse current in lower IGBT IGBT test objects: Tyco V23990-P669F02-PM

Ambient liquid: Midel 7131 transformer oil Reinforced ”EFI drivers” for pressure tolerance

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Pressure chambers for testing live power circuits

Test object in pressure chamber: 2.5 kV chip assembly phase-leg

 16 (13) liter pressure chamber  3 signal/power penetrators 8pin -1kV/10A  1 fiber optic pentrator 8-way single mode  Pressure test under commissioning

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Project progress and status 04-2010 Almost completed

Completed

Testning components in pressurized liquid environment (300 bar)

Identification of critical components

In progress Completed Enabling feasible technologies for pressurization

Testing pressure tolerant converter circuit in pressurized liquid environment (300 bar) SINTEF Energy Research

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Pressure tolerant converter module prepared for assembling in pressure vessel

Pressure tolerant converter module…..

….in pressure vessel

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