4/8/20141The University of Iowa Intelligent Systems LaboratoryGearboxAndrew KusiakIntelligent Systems Laboratory2139 Seamans CenterThe University of Iowa Iowa City, Iowa 52242 - [email protected]: 319-335-5934 Fax: 319-335-5669http://www.icaen.uiowa.edu/~ankusiakThe University of Iowa Intelligent Systems LaboratoryGearbox MountPeeters, Vandepitte, and Sas (2003) The University of Iowa Intelligent Systems LaboratoryTypical Gearboxhttp://social.windenergyupdate.com/industry-insight/turbine-longevity-pro-active-gearbox-maintenanceThe University of Iowa Intelligent Systems LaboratoryMain Shaft OptionsJ.F. Manwell et al. (2002), p. 2984/8/20142The University of Iowa Intelligent Systems LaboratoryGearbox ClassificationBasic types of gearboxes:  Parallel shaft gearbox Planetary gearboxJ.F. Manwell et al. (2002), p. 301J.F. Manwell et al. (2002), p. 300PlanetaryParallel shaftsThe University of Iowa Intelligent Systems LaboratoryGear TypesJ.F. Manwell et al. (2002), p. 267Basic type of gears: Spur (parallel teeth) Helical (teeth under angle) Herring bone (“V” shape teeth)The University of Iowa Intelligent Systems LaboratoryGearbox ConfigurationsE. Hau (2006), p. 291Single-stage gearbox=2 shaftsTwo-stage gearbox=3 shaftsThe University of Iowa Intelligent Systems LaboratoryGearbox SchematicsPoore et al. (2003)4/8/20143The University of Iowa Intelligent Systems LaboratoryStandard WT GearboxOne planetary stage and two parallel shaftsWindPower 2010The University of Iowa Intelligent Systems LaboratoryGearbox (Clipper)WindPower 2010The University of Iowa Intelligent Systems LaboratoryPower Train The power from the wind turbine rotor is transferred to the generator through the power train, i.e., the main shaft, the gearbox, and the high speed shaftThe University of Iowa Intelligent Systems LaboratoryWhy to Use a Gearbox?  Could the generator be driven directly with the power from the main shaft?  If we used an ordinary generator, directly connected to a 60 Hz AC three phase grid with two, four, or six poles, we would have to have an extremely high speedturbine with between 1200 and 3600 rpmA 40 meter rotor diameter would imply a tip speed of the rotor more than twice the speed of sound, whichis not acceptable4/8/20144The University of Iowa Intelligent Systems LaboratoryChanging Generator Rotational Speed A possibility is to build a slow-moving synchronousAC generator with many poles  If one wanted to connect the generator directly to the grid, one would end up with a 200 pole generator to arrive at a reasonable rotational speed of 30 rpm The problem is that the mass of the generator’s rotor has to be roughly proportional to the torque (turning force) it handles, therefore a direct driven generator would be heavy and expensiveThe University of Iowa Intelligent Systems LaboratoryLess Torque, More Speed  Gearboxes (converting high speed to lower speed) areused in industrial machinery and cars A turbine gearbox converts slowly rotating, high torqueof the wind turbine rotor into and high speed, low torque power, of the generator  The gearbox in a wind turbine does not "change gears"  It normally has a single gear ratio between the rotation of the rotor and the generator  For a 600 or 750 kW machine, the gear ratio is approximately 1 to 50 (Europe)The University of Iowa Intelligent Systems LaboratoryLess Torque, More Speed This particular gearbox is somewhat unusual, since it has flanges for two generators on the high speed side (to the right) 1.5 MW turbine gearbox The orange gadgets just below the generator attachments to the right are the hydraulically operated emergency disc brakes  In the background the lower part of a nacelle for a 1.5 MW turbine can be seenThe University of Iowa Intelligent Systems LaboratoryHistory of Gearboxes 35 kW: Helical stage gearboxes ~ 1979 100 – 200 kW: Helical stage gearboxes ~ 1989 600 – 900 kW: Helical/planetary gearboxes ~ 1995 1 – 2 MW: Helical/planetary gearboxes ~ 2000 5 MW: Double planetary gearboxes ~ 20054/8/20145The University of Iowa Intelligent Systems LaboratoryReliabilityTransition from kW to MW Components Accessories SystemsThe University of Iowa Intelligent Systems LaboratoryFailure Frequency and DowntimeB. Hahn, ISET The University of Iowa Intelligent Systems LaboratoryCondition Monitoring Theory: P-F CurvePF = Potential Failure, F = FailureR. Dupuis (2008), GasTOPSCondition indicatorThe University of Iowa Intelligent Systems LaboratoryReliability Analysis and TestingNREL (2007)ABC4/8/20146The University of Iowa Intelligent Systems LaboratoryDrive Train AnalysisModel of Gearbox using SimPack™ softwareNREL (2007)AThe University of Iowa Intelligent Systems LaboratoryNREL 2.5 MW Dynamometer Testing FacilityNREL (2007)BThe University of Iowa Intelligent Systems LaboratoryPonnequin Farm Test Site, COChttp://fsv.homestead.com/Ponnequin.htmlThe University of Iowa Intelligent Systems LaboratoryAcknowledgementThe material included in the presentation comes largely from the Danish Wind Industry