With or without gearbox? Drive train development for wind turbines (from a supplier perspective) Technologie-Workshop Windenergie Quo Vadis? Andreas Urban / Business Engineer SKF Österreich AG 2010-12-02
1 The dynamic wind energy market October 30, 2007 SKF Group Slide 2
Wind energy is a fast growing market Strong growth in Asia (China) Within the next 10 years 6 times the capacity Offshore is coming October 30, 2007 SKF Group Slide 3
2 Thoughts on further drive train developments October 30, 2007 SKF Group Slide 4
Basic drive train concepts: integration degree Degree of integration Turbines with gearbox Hybrid Turbines Gearless Turbines (Direct Drive) Generator speeds [rpm] 1200 1800 150-400 12-30 October 30, 2007 SKF Group Slide 5
Geared vs. Gearless 85% geared 15% gearless Will this picture change in the coming years? If so, what are the drivers? October 30, 2007 SKF Group Slide 6
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 October 30, 2007 SKF Group Slide 7
Design considerations reliability Source: Reliawind October 30, 2007 SKF Group Slide 8
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 October 30, 2007 SKF Group Slide 9
Basic drive train concepts: integration degree Degree of integration Turbines with gearbox 2-point suspension 2 separate housings 1 joint housing SRB DRTRB +CARB +CRB (SRB+SRB) (TRB+TRB) October 30, 2007 SKF Group Slide 10 3-point suspension 1 bearing in gearbox SRB Nautilus Direct Drive Moment bearing (no shaft) 2-point suspension Moment bearing Integrated in gearbox Full integration Common hub + axis No axis Nautilus Nautilus Moment bearing (no shaft) separate Hybrid Turbine DRTRB +CRB TRB+TRB Nautilus
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 October 30, 2007 SKF Group Slide 11
Key challenges in wind gearboxes Bearings fail mainly in the planetary stage on high speed shafts BUT: Bearings are often not the root cause of failures! October 30, 2007 SKF Group Slide 12
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 October 30, 2007 SKF Group Slide 13
Key challenges in wind generators October 30, 2007 SKF Group Slide 14
Design considerations - weight gearless hybrid Source EER (Emerging Energy Research) October 30, 2007 SKF Group Slide 15
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 October 30, 2007 SKF Group Slide 16 CAPEX Capital expenditure OPEX Operational expenditure
How will the future WTG look like? Race on reliability? New concepts? Innovation vs. evolution? October 30, 2007 SKF Group Slide 17
SKF contribution to wind turbine technology Condition Gearbox bearings Engineering Monitoring TRB/CRB/SRB/CARB/DRTRB Consultancy WindCon/WebCon Services Monitoring and diagnostics services Automatic distributed lubrication system Pitch bearings Sealing solutions Plain bearings Mechanical repairs & refurbishment Mainshaft bearing(s) SRB/CARB/TRB/CRB//Nautilus Maintenance tools and grease Generator bearings DGBB/Insocoat/Hybrid Yaw bearing Couplings Mainshaft housings and locknuts Bolt tensioning tools Tower alignment services October 30, 2007 SKF Group Slide 18
October 30, 2007 SKF Group Slide 19