Download - Introduction of the Sway Turbine ST10
IQPC 3rd International Conference
Drivetrain Concepts for Wind Turbines
22-24 October 2012
Swissôtel Bremen, Germany
Introduction of the
Sway Turbine ST10
Eystein Borgen
CTO Sway Turbine AS
1
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Reproduction without written permission strictly forbidden
2
To be presented:
• Sway Turbine’s new large
diameter generator technology
with ironless stator core
• Generator and blade rotor
integration
• Weight and cost advantages
• Cost of energy prospects
compared to state of the art DD
turbines
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Who are we?
– Sway AS founded in Norway 2000 (floating foundations for wind turbines)
– De-merged into two independent companies in 2010:
– Sway AS (development of floating foundations for wind turbines)
– Sway Turbine AS (10MW wind turbine development, for fixed and floating foundations)
– Sway Turbine AS is a technology company
– Commercialization of the technology with preferred industrial partner(s)
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The challenge
• High Balance of Plant cost per unit related to:
– Installation
– In-field transmission (connection by submerged cable)
– Operation & Maintenance (O&M)
• Less units, i.e. larger turbines, may reduce the above costs
BUT: The cost per MW of the wind turbine itself increases by size (cube-square law)
• 10MW turbine development with ironless generator stator initiated by Sway Turbine in 2005 to overcome this challenge
• Approximately 70 engineers have been involved
• € 20 million spent on the development and design phase
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Reproduction without written permission strictly forbidden
Top Head Mass comparison
Mass conventional DD turbine (te)
Sway Turbine scaled to 5MW (te)
Comment
280 201/ 185*
*Blade supports in composite (-34%)
Mass conventional DD turbine (te) Sway Turbine ST10 (te)
Comment
770 625 Prototype mass (-19%)
570 Expected mass after optimalisation (-26%)
530 Blade supports in composite (-31%)
Top Head Mass of 5MW-115m diameter rotor
Top Head Mass of 10MW-164m diameter rotor
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Reproduction without written permission strictly forbidden
ST10 specification • Power regulation: Pitch regulated with variable speed
• Rated power: 10MW
• Cut-in wind speed: 4 m/s
• Cut-out wind speed 28 m/s
• Nominal rotor speed 12 rpm (tip speed 103m/s)
• Operational temperature range : -10- +30 deg C (North sea)
• Extreme temperature range: -20- +40 degC
• Wind class IEC: IEC S
• Annual average wind speed: 10,0 m/s
• Turbulence intensity: IEC B
• Structural design lifetime: 20 years
• Main bearings design life time: 40 years +
• Rotor diameter: 164 m
• Blade length: 67 m
• Generator type: PM synchronous axial flux with ironless stator windings
• Nominal generator voltage: 3.5kV
• Converter type: Full 4Q converter
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Why ironless stator core?
Ironless stator core
• No attracting forces. No cogging, ”forgiving” to large air gap variations, flexible generator structure possible
• More usage of magnets on same dimensions, stator is a part of the air gap
• Large generator diameter reduces the magnet usage.
• No laminated iron in either the stator or rotor
• Generator structure lighter
Iron core
• Large forces between rotor and stator in case off centered, High stiffness and production tolerances needed.
• Less magnet usage on same dimensions, due to small air gap
• Air gap integrety brings on a lot of mass for larger diameters (T ~ k*D^2*L). Large diameter difficult to realize
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Reproduction without written permission strictly forbidden
Permanent Magnets in Generator
• Low cost magnets can be used (35-40% lower price)
• The total cost of PM is equivalent to a conventional PM machine.
• There is no laminated iron in either the stator or rotor, saving considerable cost relative to conventional direct drive generators
• The generator structure in the ST10 is 55-60% lighter than in an equivalent size conventional DD PM generator
• Total cost saving of generator of approx. 20%
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Reproduction without written permission strictly forbidden
• Parametrizized model
• OD, L, f,ag, and current loading varied
• 65 000 machines investigated
• Sensitivity curves used as design
input for the overall design
• Electro magnetic calc’s calibrated with 50kW . scaled prototype
Optimizing the generator
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Main Features, Generator
-
• Segmented 25m diameter generator
• Passive air cooling through open air gap
• Both stator segments and rotor magnets totally
encapsulated to resist the offshore environment
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Generator stator
De-moulding of full scale stator segments
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Generator and blade rotor integration
10MW -164m rotor diameter:
Generator mass:
Conv. PM DD:373te
ST10: 162te
6% less turbine costs
Blade mass (3 off)
Conv. :133te
ST10: 71te
10%-4%= 6% less turbine costs
2 ”small” main bearings on fixed
shaft
Several suppliers identified for
each of the large components
Main bearing masses:
Conventional PM DD:18te
ST10: 2x4te
6% less turbine costs
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Generator and blade rotor integration
-
• Special direct coupling
between blade rotor
and generator short
torque loop saves
weight +air-gap in
generator not affected
by the rotor blade loads
• Generator rotor
yoke has double
function; carries
both magnetic flux
and edgewise
gravity loads
between the
blades
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Generator and blade rotor integration
-
• Generator rotor and stator
included in global dynamic
analysis (air gap
clearances and forces)
• Inertial loads
• Short circuit
• Thermal expansion
Vibration sources:
• No gear box
• No generator cogging
• Bearings only vibration
source
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Maintenance
All components except blades, main structural steel, main bearings and yaw bearing can be replaced by onboard crane and special tools
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Weight and cost advantages
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1200,00
0 2 4 6 8 10 12
we
igh
t (t
e))
Size (MW)
Top head Weight comparison, Large rotor size
Conventional PM DD Turbine weight (331W/m2)
Sway Turbine weight (331W/m2)
Issue to keep in mind:
• Extensive thrust clipping (latest
6-7MW conventional designs)
reduces weight of turbine but
also reduces annual energy
production
The ST10 uses only limited thrust
clipping
The overall Sway Turbine solution
should result into 20-30% lower
weight and 15-20% lower turbine
cost
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0 2 4 6 8 10 12
we
igh
t (t
e))
Size (MW)
Top head Weight comparison, medium rotor size
Conventional PM DD Turbine weight (480W/m2)Sway Turbine weight (480W/m2)
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Cost of Energy (CoE) input assumptions
• 490MW wind farm 40km from shore, 30m water depth (fixed) and 120m
water depth (floating).
• IRR of 10.9% on the total wind farm CAPEX
• Manufacturing costs are based on European costs levels
• 3 different generator to rotor area ratios; medium (480W/m2), medium to large (405W/m2) and large (331W/m2)
The Cost of Energy calculations includes: • Electrical grid connection to shore + onshore grid reinforcement • 33% additional costs of wind turbine due to offshore application (additional
corrosion protection, landing platforms, market factor, warranty risk etc) • 10% contingency on total farm Capex and 10% profit to the OEM.
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
CoE fixed foundations, 10m/s
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0 5 10 15 20 25
Co
st o
f En
erg
y (€
cen
t/kW
h)
Turbine size (MW)
COE - Conventional DD PM turbines versus Sway Turbine (ST), both on fixed foundations, 10m/s site, 10.9%IRR, Foundation and installation calibrated with wind farm operator’s cost model.
Conventional Turbine DD PM Medium rotor diam. 480W/m2 on fixed foundation
Conventional Turbine DD PM Medium to large rotor diam. 405W/m2 on fixed foundation
Conventional Turbine DD PM Large rotor diam. 331W/m2 on fixed foundation
Sway Turbine (ST) Medium rotor diam 480w/m2 on fixed foundation
Sway Turbine (ST) Medium to large rotor diam. 405W/m2 on fixed foundation
Sway Turbine (ST) Large rotor diam. 331W/m2 on fixed foundation
ST10-164
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
CoE fixed foundations, 9m/s
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20
0 5 10 15 20 25
Co
st o
f E
ne
rgy
(€
cen
t/k
Wh
)
Turbine size (MW)
COE - Conventional DD PM turbines versus Sway Turbine (ST), both on fixed foundations, 9m/s site, 10.9%IRR, Foundation and installation calibrated with wind farm operator’s cost model.
Conventional Turbine DD PM Medium rotor diam. 480W/m2 on fixed foundation
Conventional Turbine DD PM Medium to large rotor diam. 405W/m2 on fixed foundation
Conventional Turbine DD PM Large rotor diam. 331W/m2 on fixed foundation
Sway Turbine (ST) Medium rotor diam 480w/m2 on fixed foundation
Sway Turbine (ST) Medium to large rotor diam. 405W/m2 on fixed foundation
Sway Turbine (ST) Large rotor diam. 331W/m2 on fixed foundation
ST10-164
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
CoE floating, 10m/s
12
13
14
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19
20
0 5 10 15 20 25
Co
st o
f En
erg
y (€
cen
t/kW
h)
Turbine size (MW)
COE - Conventional DD PM turbine versus Sway Turbine, both on Sway foundations, 10m/s site, 10.9%IRR
Conventional Turbine DD PM Medium rotor diam. 480W/m2- on Sway floating foundation
Conventional Turbine DD PM Medium to large rotor diam. 405W/m2- on Sway floating foundation
Conventional Turbine DD PM Large rotor diam. 331W/m2- on Sway floating foundation
Sway Turbine (ST) Medium rotor diam. 480W/m2- on Sway floating foundation
Sway Turbine (ST) Medium to large rotor diam. 405W/m2- on Sway floating foundation
Sway Turbine (ST) Large rotor diam. 331W/m2- on Sway floating foundation
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
Summary: (apple to apple 10MW-164m rotor diam.)
Generator -6% turbine cost
Blades -6% turbine cost
Main bearing -6% turbine cost
Misc. -4% turbine cost
Fewer units. Less balance of plant costs.
Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden
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Thank you! Sway Turbine AS proprietary
Reproduction without written permission strictly forbidden