Dr.-Ing. Andreas Vath Bosch Rexroth AG Wind Turbine Drive Train ...

Bosch Rexroth AGWind Turbine Drive Train Innovationsand Load Reduction SolutionsDr.-Ing. Andreas VathBosch Rexroth AG1A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Content• motivation• combining benefits of existing drive trains for wind turbines• direct drive• high speed• medium speed• differential gearbox benefits in medium speed concepts• Bosch Rexroth load reduction solutions• Active Torque Control (ATC)• Individual Pitch Control (IPC)• summary2A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Motivation for drive train innovations and load reduction solutionsDesign challenge: Reducing cost of energyOnshore: Larger rotors1.5 - 3 MWseries4 MWdevelopmentOffshore: Larger turbines3 MWseries5 -7 MWprototype>10 MWtransportrestrictionsfuturehigher drive train requirementsdrive train innovationsreliableefficientlow costload reduction solutionsfor wind turbines3A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Content• motivation• combining benefits of existing drive trains for wind turbines• direct drive• high speed• medium speed• differential gearbox benefits in medium speed concepts• Bosch Rexroth load reduction solutions• Active Torque Control (ATC)• Individual Pitch Control (IPC)• summary4A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Comparison of drive train efficienciesdirect drive high speed medium speeddirectdrivedrive train efficiencymedium speed concepthigh speed conceptdirect driveefficiencymedium speed concepthigh speed conceptwind speed in m/sMedium speed concepts:- high partial load efficiency- high drive train full load efficiency of 94%(gearbox >98.0%; generator 98.3%;frequency converter 97.5%)⇒ high energy yield at high averagewind speedsMedium-speed concepts: High efficiency leads to high energy yield5A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Drive train weight and raw material cost of a 3 MW wind turbinedirect drive high speed medium speedweight in tonsdrive train weightmagnetscopperironcost in t€raw material cost for drive train*rare earthcopperiron0directdrivemediumspeedhighspeeddirectdrivemediumspeedhighspeed*Neodymium 120 €/kg, Dysprosium 1300 €/kg, Copper 7 €/kg, Iron 1 €/kglow amount of raw materialslow drive train material costsDrive train weight and cost advantage with gearbox concepts6A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Cost of energy comparison for an example onshore turbineMain assumptions• rated power 3MW• rotor diameter 115 m• 6.5 m/s average wind speed• 20 years design life time• raw material cost:- copper 7€ per kg- steel 1€ per kg- magnets 100€ per kg• complete wind farm cost 1700 to1900 € kW depending on drivetrain conceptCost of energy [€/kWh]8.58.07.57.06.56.05.50Innovationsfor furthercostreduction1 2 3 4 5• 97% availability of all concepts• operation & maintenance costs forcomplete turbine (additional costsfor gearbox oil change considered)• same blade, hub and tower designof different drive train concepts• higher cost of energy of direct drives due to the highamounts of raw and rare earth material• lower cost of energy with high speed and mediumspeed solutionsFC: frequency converter; SESG: separately excited synchronous generator, PMSG: permanently excited synchronous generator;DFIG: doubly fed induction generator; HTS-SG: high-temperature superconducting synchronous generator,7A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Content• motivation• combining benefits of existing drive trains for wind turbines• direct drive• high speed• medium speed• differential gearbox benefits in medium speed concepts• Bosch Rexroth load reduction solutions• Active Torque Control (ATC)• Individual Pitch Control (IPC)• summary8A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Bosch Rexroth differential gearbox for medium speed conceptstorque splitting stagedifferential stagefor torque summaryi = 10 -15inputtorque:i = 3-4outputtorquetorque splitting topologywith equal load distributionto 6 planets+ equal load distribution to 6 planets+ statically defined system+ reduced loads on bearings/toothingi total = 30-60proven concept inhigh speed drive train conceptsfor more than 7 years andmore than 1300 installed units+ higher reliability+ higher power density+ less material consumptionHigh gearbox ratio possible with torque splitting and differential stage9A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Effect of higher gear ratio for medium speed conceptsInvestment costs100 %generatorgearboxi=40generatorgearboxi=60• higher generator speed means lesstorque at same rated power• generator costs are proportional tothe generator torque⇒ generator cost reduction withBosch Rexroth differentialgearbox REDULUS GPVconventionaldesignBosch RexrothDesign REDULUS GPV⇒ Reduced drive train costs with differential gearbox REDULUS GPV10A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Content• motivation• combining benefits of existing drive trains for wind turbines• direct drive• high speed• medium speed• differential gearbox benefits in medium speed concepts• Bosch Rexroth load reduction solutions• Active Torque Control (ATC)• Individual Pitch Control (IPC)• summary11A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Load reduction solutionsActive Torque Control (ATC)Active damping ofdynamical loads1Active torque control12Active torquecontrolIndividual pitchcontrol• Dynamic control ofdrive train torque toreduce peak loads andFuture wind turbines:Load-reduced operationtorque oscillations21⇒ higher drive trainlifetime and reliabilityPreventing and reducingloading by means ofinnovative approaches⇒ lower cost of energyLoad reduction for torque with active torque control12A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Sensor and control system for Active Torque ControlSCUControl unitSensorDrive traintorqueGenerator torqueadjustment• Dynamic measurement ofdrive train speed by usingadapted automotivesensors• Calculation of the drivetrain torquePatented by Bosch Rexroth• Control strategy to reducedrive train torque andspeed oscillations bygenerator torqueadjustment13A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Torque [kNm]Measurement results of Active Torque ControlDrive train torque and speed1750150012501000750500250withoutATCDrive train torquewith ATC00 10 20 30 40Time [s]Speed [rpm]1514.914.8Drive train speedwith ATCwithout ATC14.715 16 17 18 19Time [s]Reduction of drive trainspeed oscillations as aresult of less drive traintorque oscillationsHigh reduction of drive train torque and speed oscillations14A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Active Torque Control of wind turbinesDrive train torquewithout ATCwith ATC1-10%FwithoutATCwithATCForce at tooth xDamaging loads1-10%FBearing forcewithoutATCDamaging loadsReduction of equivalent damage loads at toothing and bearingswithATC15A. Vath | Active Torque Control| Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction, distribution, aswell as in the event of applications for industrial property rights.

Active Torque Control of wind turbinesDrive train benefitsBenefits of active torque control• Increase of nominal power when using active torque control⇒ higher energy yield• Less blade oscillations and therefore better aerodynamics⇒ higher energy yield• Advantages for gears andbearings due to lowertorque oscillations• Structural advantages dueto less deformationscaused by oscillations• Increase of bearinglifetime because of lessspeed oscillations16A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Drive train innovations and load reduction solutionsLoad reduction: Individual pitch controlActive damping ofdynamic loads2Individual Pitch Control121Active torquecontrolIndividual pitchcontrolPreventing and reducingloading by means ofinnovative approaches2• Measurement of bendingmoments in each blade• Controller for bendingmoment reduction• Continuously pitching ofeach bladeBending momentreduction in %blades towermainshaftFuture wind turbines:Load-reduced operationEffect on wind turbines:Reduced weight and cost andincreased energy generationLoad reduction for bending moments up to 25% with individual pitch control17A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Content• motivation• combining benefits of existing drive trains for wind turbines• direct drive• high speed• medium speed• differential gearbox benefits in medium speed concepts• Bosch Rexroth load reduction solutions• Active Torque Control (ATC)• Individual Pitch Control (IPC)• summary18A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

SummaryDrive train innovations• Wind turbines with reliable high speed and medium speed drive conceptswill provide the lowest cost of energy• High drive train cost reduction with the Bosch Rexroth differential gearboxREDULUS GPV in medium speed solutionsLoad reduction solutions• Bosch Rexroth active torque control significantly reduces drive traintorque and speed oscillations higher reliability, higher energy yieldand reduction in cost of energy• Individual pitch control contributes to load reduction• Load-reduced operation necessary for further optimization of future windturbines19A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.

Bosch Rexroth: Components and solutions for wind turbineselectricpitch systemsgearbox cooling & filtrationgearboxesservicehydraulicpitch systemsrotor bladecondition monitoringbrake and hydraulicpower UnitsThank you very much for your attention!See you at our booth! Hall3 D1220A. Vath | Wind Turbines Innovations | Sept. 2012 | © Bosch Rexroth AG 2010. All rights reserved, also regarding any disposal, exploitation, reproduction,distribution, as well as in the event of applications for industrial property rights.