Hydraulic Control Technology for Wind Turbine ... - Bosch Rexroth

IndustrialHydraulicsElectric Drivesand ControlsLinear Motion andAssembly TechnologiesPneumaticsServiceAutomationMobileHydraulicsHydraulic Control Technologyfor Wind Turbine GeneratorsExtra efficiency in manufacture, operation and maintenance

2Environment-Friendly Power Generation withHydraulic Control Technology from RexrothPitch controlDrive train brakeYaw systemSubassembliesPower unitsMotor-pumpgroupsAccumulatorsFilter and coolersubassemblies

3The future belongs to energygeneration from “renewablesources”. A fine example of thisis the generation of electricityfrom wind power. The moreefficiently the technologicalgroundwork is accomplished– from development and ope-ration through to maintenanceof the turbine – the fastersustainable energy generationmethods will establish themselvesin the marketplace.The comprehensive drive & controlexpertise of Rexroth makes windturbines more efficient – thanksparticularly to the technologicaladvantages of hydraulics in termsof high power density in limitedspace, low-maintenance and ruggeddesign and, not least, outstandingcontrollability:Boosting efficiency:• More precise actuator drives• Shorter control cyclesLow production costs:• Simulation techniques to speedup development• Modular design through to thesubsystem• The entire technology from asingle source• Less assembly effort• Simpler commissioningLow operating costs:• Longer maintenance intervals• Reducing loads• Preventing overload• Low wearManufacturers receive all thetechnology from a single source– standardized from a broad rangeof proven components or modifiedto customer specification. Owingto its outstanding knowledge of theindustry, Rexroth, in its capacityas a component manufacturer andsystem supplier, can make anyrequired modifications directly.As a result of its worldwide presence,Rexroth contacts are alwaysclose to the customer.

4Ideally Positioned –Thanks to Precision Pitch ControlThe availability of wind and gridcapacity are the decisive factors forthe wind turbine’s operationalstate – with proportional valves forflexible adaptation. In normaloperation the positioning motionscan be executed sensitively andslowly to minimize stressing of thematerials, while in extreme conditionsthey are performed suitablyquickly to prevent damage to theturbine.The ideal rotor blade pitch is accuratelyset by hydraulic cylinders.Cylinder performance dependson the seal system. The standardseal system is pressure-loaded withpressure-dependent friction; thehigh-performance seal systemoperates pressure-unloaded withpressure-independent friction.Rexroth cylinders are availablewith either system, depending onthe customer’s specific needs.The cylinder is controlled byproportional valves in numerouspossible variants:Valves with• External electronics• Integrated electronics• Integrated electronics andposition controllerCommand value selection via a• Current interface• Voltage interface• Field busValve characteristic curves• Linear• Progressive• CustomizedStandard seal system:Pressure-loaded with pressuredependentfrictionHigh-performance sealsystem: Pressure-unloaded withpressure-independent friction

5Cylinders precisely controlledby proven, compact open andclosed-loop control systemsfrom Rexroth.As the central drive element, thecontrol block unites all the componentsin a single subassembly.As a result of its dual function as acomponent carrier and connectingelement, the entire drive has beengiven an especially compact design.In addition to savings of space andmaterials, it also provides protectionfrom environmental aggressionand physical damage.The compact cartridge valvesemployed in the central blockcontrol secondary functions:• Passive position holding• Counterbalancing• Emergency stoppingThe interaction of electrically andhydraulically operated seat valvessignificantly reduces the number ofcontrol signals and system-relatedinternal leakage.

6Slowly but Surely –the Drive Train BrakeModulated pressure permits awide variety of functions:· Speed-controlled braking· Torque-controlled braking· Position-controlled braking· Gentle braking· Emergency braking· Position holdingIn uncontrolled braking processes,the torque transmitted by thegearbox can easily exceed severaltimes the rated torque and thuscause damage to the gearwheelsand bearings. Time-consumingand hence costly failure, repair andreplacement are the consequence.Leading manufacturers of windturbines therefore opt for thehydraulic modulation of brakingpressure. To this end an independenthydraulic unit is employedto control all braking systems andcircuits. With the aid of on/offvalves, simple braking and holdingfunctions are performed – servo,proportional and high-responsevalves give valuable plant componentsmaximum protection fromoverload and damage.All the valves are seat valves andthus enable braking pressure to bemaintained for extended periods,even during power failures.

10Mechanical drive technologyfor wind turbine generators:• Generator gear units• Pitch gear units• Azimuth gear unitsBrochure No.: RE 76110Rexroth accumulatorsubassembliesHydraulic accumulators not onlyserve as an energy reserve inemergencies, but also cover peakdemand.The advantage of this is that theinstalled power can be much lower,thus yielding savings in componentsizes and energy consumption.Wind turbines need special bladder-typeaccumulators that reducethe frictional wear occurring inrotary systems and withstand extremelylow temperatures. Rexrothaccumulators fill the bill perfectly.Rexroth filter-cooler modulesClean and cool oil is essential if thehydraulics system is to enjoy a longservice life. For use in wind turbines,Rexroth supplies modules indifferent power categories.With long supply lines, this subassemblycan be used as a feed pumpin order to prevent cavitationdamage to the main pump. Thesystem oil can be changed here.The subassembly can be integratedwith ease into existing systems.

IndustrialHydraulicsIntelligent hydraulicsin new dimensionsThe Drive & Control CompanyBosch Rexroth offers an uniqueand comprehensive range ofproducts and services acrosstechnologies from a single sourcein its six fields of technology andservice areas – strong in highqualityindividual technologies,combined with highest application-specificcompetence insystem packages with integratedcomplete solutions.ElectricDrives andControlsLinearMotion andAssemblyTechnologiesPneumaticsServiceAutomationMobileHydraulicsWherever forces need to be utilizedeconomically, the advantages of industrialhydraulics are obvious –whether it is required to lift and lowerloads smoothly, perform linearor rotary movements, achieve constantacceleration, maintain givenspeeds, approach positions exactly,transmit powers or interlink sequences.Rexroth is the technology andmarket leader in industrial hydraulicswith a comprehensive productrange and distinct applicationexpertise.At Rexroth you can select from theworlds’ largest standard productrange in the field of hydraulics,application and customer-specificsystem solutions of high quality.With advanced micro-electronicsRexroth has made hydraulics evenmore powerful.For you, Rexroth is the ideal partnerfor developing highly efficientmachines and production facilities– from the first point of contact tocommissioning and throughout theentire life cycle. Teams that operateworldwide carry out the completeengineering of your systems and,if requested, up to the hand-overof turnkey systems and beyond –service included.Thanks to the use of hydraulicdrive and control technology fromRexroth you will be more competitivethan ever.Rely on service acrosstechnologiesRexroth integrates all services forthe entire product spectrum inthe field of factory and industrialautomation into a single organization:from immediate support,spare parts service, field and repairservice, retrofit/modernizationthrough to training.

Bosch Rexroth AGIndustrial HydraulicsZum Eisengießer 197816 Lohr, GermanyPhone: +49(0)9352/18-1237Fax: +49(0)9352/18-1222application-centre@boschrexroth.dewww.boschrexroth.comPrinted in GermanyRE 00065/08.03substitutes RE 00065/03.03