With or without gearbox? Drive train development for wind ...

With or without gearbox? Drive train development for wind turbines

Technologie-Workshop “Windenergie – Quo Vadis?”

Andreas Urban / Business Engineer SKF Österreich AG

2010-12-02

(from a supplier perspective)

October 30, 2007 © SKF Group Slide 2

The dynamic wind energy market

1


Wind energy is a fast growing market

Within the next 10 years 6 times

the capacity

Offshore is coming

Strong growth in Asia (China)


2 Thoughts on further drive train developments


Basic drive train concepts: integration degree

Gearless Turbines (Direct Drive)

Turbines with gearbox Hybrid Turbines

Generator speeds [rpm] 1200 – 1800 150 - 400 12-30

Degree of integration


Geared vs. Gearless

Will this picture change in the coming years?

If so, what are the drivers?

85% geared 15% gearless


Main issues and trends

•  In many new developments for Multi-Megawatt turbines geared versions are slowly loosing ground in favor of hybrid and direct drive ones – but why?

•  Reliability is more and more becoming a major issue – less components less risk of failures?

•  Emerging offshore taking off – increased need of high reliability •  Reduce O&M cost, low maintenance efforts, lower lifetime cost/kWh electricity •  Requirements for increased service life •  Expanding turbine warranty periods •  Easy maintainability and replaceability •  Optimize turbine efficiency •  Drive train integrations •  Reduce nacelle weight (compact designs) •  Reduce turbine cost •  Supply chain and logistics constraints •  Shift in new turbines designs in favor of stiff

rotor bearing arrangements


Design considerations – reliability

Source: Reliawind


Key challenges on main shafts

Main shaft challenges: •  Ambient conditions, understanding of loads induced •  Design philosophy (rigid/flexible) •  Serviceability •  Space limitations •  Integration vs. disintegration •  Weight •  Structural deformations •  Cost vs. Quality •  Design for reliability

In particular for bearings: •  Bearing selection for stiffness resp. flexibility •  High load, high torque and low speed application •  Permanently changing loads and torque •  Extreme loads •  Lubrication regime and contamination


Basic drive train concepts: integration degree

Degree of integration

2-point suspension 3-point suspension

Moment bearing (no shaft)

2 separate housings

1 joint housing

1 bearing in gearbox separate Integrated

in gearbox

Moment bearing (no shaft)

Full integration

2-point suspension

Moment bearing

Common hub + axis No axis

Turbines with gearbox Hybrid Turbine

Direct Drive

Nautilus DRTRB+CRB TRB+TRB

Nautilus SRB+CARB

DRTRB+CRB

SRB Nautilus Nautilus (TRB+TRB) (SRB+SRB)


Key challenges in wind gearboxes

Wind gearbox challenges: •  Ambient conditions, understanding of loads induced •  Serviceability •  Space limitations •  Weight •  Vibration characteristics and levels •  Cost vs. Features vs. Quality vs. Availability •  Design for reliability

In particular for bearings: •  Extremely high torque at very low speed •  Low load and high speed applications •  Low speed and torque (idling) •  Permanently changing loads and torque •  Extreme loads, brake loads & negative torque •  Oil cleanliness, lubrication regime and contamination


Key challenges in wind gearboxes

BUT: Bearings are often not the root cause of failures!

Bearings fail mainly

  in the planetary stage

  on high speed shafts


Key challenges in wind generators

Wind generator challenges: •  Ambient conditions, understanding of loads

induced •  Serviceability •  Space limitations, compactness •  Weight •  Vibration characteristics and levels •  Cost vs. Quality vs. Availability •  Design for reliability and robustness •  Noise levels •  Efficiency

In particular for bearings: •  Lubrication regime – wear and starvation problems •  Vibration and shock loads •  Contamination •  Electrical erosion •  Quiet running (noise and vibration levels) •  Temperatures


Key challenges in wind generators


Design considerations - weight

Source EER (Emerging Energy Research)

gearless hybrid


Design considerations

Criteria Geared Gearless Remarks

CAPEX o o To be proven

OPEX o + If reliability really higher for gearless

Reliability o + Less components – less failures Really true?

Supply chain - Logistics

+ o Rare earth?

Serviceability o o To be proven

Efficiency o + No gearbox friction losses avoided

Weight + o Refer to previous slide

CAPEX … Capital expenditure

OPEX … Operational expenditure


How will the future WTG look like?

Race on reliability?

New concepts?

Innovation vs. evolution?


Pitch bearings

Yaw bearing

Mainshaft housings and locknuts

Condition Monitoring WindCon/WebCon

Couplings

Automatic distributed lubrication system

Monitoring and diagnostics services

Mechanical repairs & refurbishment

Sealing solutions

Bolt tensioning tools

Tower alignment services

Engineering Consultancy Services

Plain bearings

Maintenance tools and grease

SKF contribution to wind turbine technology

Gearbox bearings TRB/CRB/SRB/CARB/DRTRB

Generator bearings DGBB/Insocoat/Hybrid

Mainshaft bearing(s) SRB/CARB/TRB/CRB//Nautilus

With or without gearbox? Drive train development for wind ...

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