Gearbox Reliability Collaborative - Phase 1 And 2 Overview .

Gearbox Reliability Collaborative Phase 1 and 2 OverviewSandia TurbineReliability WorkshopAug 2-3, 2011Hal LinkNREL/PR-5000-52463NREL PIX # 19222NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Why GRC? Wind turbine gearboxes do not last their 20 year design life Designs must meet design, manufacturer, and testingstandards and certification requirements Problems have occurred throughout the wind industry Problems range across the turbine design cycle load characterization design methods model fidelity testing/validation methods Competition inhibits communication and joint solutionsNATIONAL RENEWABLE ENERGY LABORATORY2

Major Elements of GRC Collaboration - form a team of stakeholders includingmanufacturers, owners, researchers Generic drivetrain - Identify and investigate“representative” test gearboxes Testing - model validation, load characterization,detailed gearbox, and subcomponent response Modeling - improve design tools and understanding Failure Database - document and analyzefailures/modes Condition Monitoring - investigate use of continuousinspection as design and O&M (operation andmaintenance) tool to improve reliabilityNATIONAL RENEWABLE ENERGY LABORATORY3

Test Article Selection and Redesign 750kW - easy to test,representative, generic 2 gearboxes for field anddyno testing 3 point mount, 1 planetstage, 2 parallel Redesigned with expertinput Upgraded using experienceof design and rebuildexperts active lubrication with kidney loopimproved tooth profile and finishimproved bearing arrangementsNATIONAL RENEWABLE ENERGY LABORATORY4

Instrumentation (and lots of it) Planet load distribution (12 gauge pairs per planet)Planet race temperature (six sensors per planet)Planet rim movement (6 sensors on two planets)Mainshaft bending and torqueRing gear load distributionCarrier deflection/movementSun radial movementGearbox movement relative to mainframeHigh speed shaft (HSS) bearing temperaturesHSS torqueHSS / Generator alignmentNATIONAL RENEWABLE ENERGY LABORATORY5

Instrumentation – Ring Gear Tooth Load DistributionStrain gauge installationin ring gear of GRCGearbox .NREL PIX #19495 (top).NREL PIX #19494 (left).NATIONAL RENEWABLE ENERGY LABORATORY6

TestingEarly testsField test: torque and modal characterizationPlanet bearing calibrationTrunnion stiffness characterizationPhase 1Dyno Gearbox 1: run-in and instrumentation checkoutField Gearbox 1: loads, responses, eventsDyno Gearbox 2: run-in, limited non-torque loadingPhase 2Dyno Gearbox 2: extensive Non-Torque Loads (NTL),dynamics, HSS misalignmentDyno Gearbox 1: NTL, condition monitoringNATIONAL RENEWABLE ENERGY LABORATORY7

Data Analysis Did we measure what we wanted accurately?Did we achieve the test conditions we wanted?What data are available and where?Can the data be released for model validation?Were unexpected loads observed?NATIONAL RENEWABLE ENERGY LABORATORY8

Gearbox ModelingGearing Analysis Gear tooth loading Gear mesh stiffness Gear tooth contactstressShaft Analysis Torsional deflections Bending defectionand misalignmentPlanet Carrier Analysis Torsional deformation of theplanet carrier Misalignment the planet pin Planet carrier and pin interactionSource: Ansol (Calyx)Housing Analysis Deflections Misalignment Tolerance stack up Virtual modal testingNATIONAL RENEWABLE ENERGY LABORATORYBearing Analysis Bearing stiffness Roller contact stress Roller load distribution Bearing life9

Gearbox Failure DatabaseStatus Development of standardizedcollection software Signed partners: 17% of USgenerating capacity representedNATIONAL RENEWABLE ENERGY LABORATORYWhy? Connects testingand simulationsto actual failures Helps to identifyroot causes offailures Sanitized datacan be sharedamong GRCmembers10

Findings1.2.3.4.5.6.NTL (bending) affects planet/ring meshOn-line particle counting for run-inController adjustments to reduce torque spikesNTL (thrust) affects carrier positionPlanet bearing load share varies significantlyExternal gauges can indicate tooth contact patternPlanet Load Share vs Main Shaft Rotation1.5ABC1.41.3300Field TorqueDyno Torque250KTorque 200250Main Shaft Azimuth [deg]300NATIONAL RENEWABLE ENERGY LABORATORY350204060Time [sec]8010012011

External Gauges Facilitate Tooth Load Measurements1.2Load 250Width Across Ring Gear [mm]NREL PIX # 19221 External gauges are MUCH easier to install Last longer and are repairable They accurately indicate the centroid of thecontact area and, potentially, edge-loading They distort measurement of the important designparameter, KhßNATIONAL RENEWABLE ENERGY LABORATORY12

Non-Torque Loads Affect GearingRing Gear Load Distribution at 120 2000M Y -180 kNm1800M Y 170 00 -UpwindGear Face WidthDownwind- M Y 170 kNm10008000M Y 0 kNm160014001000M Y -180 kNm1800M Y 0 kNm1600Ring Gear Load Distribution at 240 20000 -UpwindGear Face WidthDownwind- Non-torque loads DO affect the gearbox Mainshaft bending loads up to 180 kNm in allazimuths simulating unbalanced rotor loads Caused significant increase in tooth edge loadsNATIONAL RENEWABLE ENERGY LABORATORY13

Next Steps in GRC Continue data validation and analysis Use data and experience to identify designsensitivities for next re-design Redesign and rebuild damaged Gearbox 1- Gearbox 3 Start Phase 3 testing in the dyno and field Convene a tribology / lubrication workshopin November 2011 with experts and sharedWTG experiences from fieldNATIONAL RENEWABLE ENERGY LABORATORY14

Questions / Comments?NATIONAL RENEWABLE ENERGY LABORATORY15

Field test: torque and modal characterization. Planet bearing calibration. Trunnion stiffness characterization. Phase 1. Dyno Gearbox 1: run-in and instrumentation checkout. Field Gearbox 1: loads, responses, events. Dyno Gearbox 2: run-in, limited non-torque loading. Phase 2. Dyno Gearbox 2: extensive Non-Torque Loads (NTL), dynamics, HSS .