Abrahamsen, Asger Bech

Jensen, Bogi Bech

Mijatovic, Nenad

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Advantages and Challenges of Superconducting Wind Turbine GeneratorsJensen, Bogi Bech; Mijatovic, Nenad; Abrahamsen, Asger BechPublication date:2012Link back to DTU OrbitCitation (APA):Jensen, B. B., Mijatovic, N., & Abrahamsen, A. B. (2012). Advantages and Challenges of Superconducting WindTurbine Generators [Sound/Visual production (digital)]. 2nd International Conference E/E Systems for WindTurbines, Bremen, Germany, 21/05/2012Advantages and Challenges of Superconducting Wind Turbine GeneratorsBogi B. Jensen1, Nenad Mijatovic1, Asger B. Abrahamsen21 Department of Electrical Engineering, Technical University of Denmark, Denmark2 Department of Wind Energy, Technical University of Denmark, Denmark2nd International Conference E/E Systems for Wind Turbines21st – 23rd May 2012, Bremen, Germany2 DTU Electrical Engineering, Technical University of DenmarkOverview• Background of superconductivity and its relevance for wind turbine generators• Advantages of superconducting generators for wind turbines• Challenges of superconducting generators for wind turbines• Commercial activities3 DTU Electrical Engineering, Technical University of DenmarkBACKGROUND4 DTU Electrical Engineering, Technical University of DenmarkTechnical University of Denmark (DTU)• Based in Copenhagen, the Capital of Denmark• 8200 students – 530 faculty – 1040 researchers• Ranked 4th in Europe in the field of engineering by THE based on citations per journal paper from 2000-2010 (http://www.timeshighereducation.co.uk/story.asp?storyCode=414302&sectioncode=26) 5 DTU Electrical Engineering, Technical University of DenmarkDevelopment of wind turbinesproductionenergy  AnnualOPEX and CAPEX AnnualisedCoE 18/04/2012Development of Superconducting Wind Turbines6 DTU Electrical Engineering, Technical University of Denmark• Elimination of Gearbox• Permanent Magnet GeneratorsCurrent trendNext Generation - No GearboxConventional Turbine GeneratorPermanent MagnetCopper Wound-Coilwith Gearbox > 320 Tons> 500 Tons10 MW7 DTU Electrical Engineering, Technical University of Denmark5MW and beyondManufacturer Transmission GeneratorSiemens Wind Power Direct drive PMSG 6.0MWVestas Medium speed PMSG 7.0MWEnercon Direct drive EESG 7.5MWAlstom Direct drive PMSG 6.0MWREPower High speed DFIG 6.2MWAreva Low speed PMSG 5.0MW10MW and beyond – proposals/investigationsManufacturer Transmission GeneratorAmerican Superconductor Direct drive HTS 10MWGeneral Electric Direct drive LTS 10-15MWAdvanced Magnet Lab Direct drive MgB2 10MW18/04/2012Development of Superconducting Wind Turbines8 DTU Electrical Engineering, Technical University of DenmarkSchematic of a Superconducting Machine• The superconductor must be kept at cryogenic temperatures• The armature winding is usually proposed to be copper at ambient temperatureVBATTPvolumeVloadingmagneticBloadingelectricAspeedrotationaltorqueTpowerP::::::9 DTU Electrical Engineering, Technical University of DenmarkHigh Temperature Superconductors• The superconducting state is limited by– Critical flux density Bc– Critical current density Jc– Critical temperature Tc• Superconducting materials can becharacterised by IV curves• E0 is the electric field at the critical current (1μV/cm)( , )0[ / ]( , )n B TcJE V m EJ B T    10 DTU Electrical Engineering, Technical University of DenmarkOverview of superconductorsType Price€/mJeA/mm2Fluxdensity [T]Temp.[K]NbTi 0.4 103 5 4.2Nb3Sn 3 1-4x103 5 4.2MgB2 4 102 3 20Bi-2223 20 390103 tape3 tape2050YBCO 30 98 (480)49 (190)3 tape3 tape205018/04/2012Development of Superconducting Wind Turbines11 DTU Electrical Engineering, Technical University of DenmarkADVANTAGES18/04/2012Development of Superconducting Wind Turbines12 DTU Electrical Engineering, Technical University of DenmarkGenerator Powerlimited by stator coolinglimited by the power rating of the WT (around 10rpm at 10MW)A/m000,70A3m115MW10  PMVPrad/s05.1  pVBATP gmm cosˆ23m42MW10  HTSVPPM Generator Bg = 0.9T HTS Generator Bg = 2.5TWith an axial stack length of 2.0m, this would result in a airgap diameter of:Dg = 8.6m Dg = 5.2m18/04/2012Development of Superconducting Wind Turbines13 DTU Electrical Engineering, Technical University of DenmarkPM in wind turbines• A 6MW direct drive wind turbine is estimated to use 5 tons of permanent magnets• This is the same as 2500 Toyota Prius• Should we be worried?x250018/04/2012Development of Superconducting Wind Turbines14 DTU Electrical Engineering, Technical University of DenmarkSummary• Very high torque density• Very limited dependence on rare earth materials• Higher efficiency than an equivalent direct drive PM generatorVBATTP  ,mR = 0.27mR-B-FePM HTSHybrid50kgR/MW 20gR/MWDirect drive250kgR/MW 100gR/MWCuCuCu RIP2CuCuCuCuCuAlAJ22CuCuCu VJ215 DTU Electrical Engineering, Technical University of DenmarkCHALLENGES18/04/2012Development of Superconducting Wind Turbines16 DTU Electrical Engineering, Technical University of DenmarkCooling system• The superconductors need to be cold:<5K for LTS<20K for MgB230-50K for HTS• Insulation requires large effective airgap– Large fault currents and torques• Torque transfer• Reliability has yet to be proven and requires years of operating experience• Production capacity of HTS and MgB2 are currently not adequate for large-scale commercialisation – this should change if the need is present18/04/2012Development of Superconducting Wind Turbines17 DTU Electrical Engineering, Technical University of Denmark• Size and weight do not necessarily scale linearly• Iron coreback is required to shield the magnetic field from ambient• Not as cheap to increase the number of polesSize and weightVBATTP  ,2 Poles 10 PolesSource: H. Ohsaki et al. “Electromagnetic Characteristics of 10 MW Class Superconducting Wind Turbine Generators”, ICEMS, 2010.18/04/2012Development of Superconducting Wind Turbines18 DTU Electrical Engineering, Technical University of DenmarkMass, HTS length and price as a function of pole number18/04/2012Development of Superconducting Wind Turbines19 DTU Electrical Engineering, Technical University of DenmarkCost of HTS and PM in a 10MW wind turbine• If 400km of 4mm HTS tape is assumed for a 10MW wind turbine generator• With a current carrying capacity of 80A and a price of €50/kAm, this gives €4/m• The cost of the HTS tape for a 10MW would therefore be €1.6 million• In addition the cryostat, cryocooler etc. will have to be added• PM price today? €50/kg• If 10 tons of PM is required for a 10MW wind turbine• The cost of the PM for a 10MW would be k€50018/04/2012Development of Superconducting Wind Turbines20 DTU Electrical Engineering, Technical University of DenmarkFuture cost of HTS must/will come down• It is not unlikely that the price of HTS tape will come down to €15/kAm• This would result in €480,000 for a 10MW wind turbine• This would be competitive with PM technology• But it is clear that the usage of HTS tape must be minimised!18/04/2012Development of Superconducting Wind Turbines21 DTU Electrical Engineering, Technical University of DenmarkCOMMERCIAL ACTIVITIES18/04/2012Development of Superconducting Wind Turbines22 DTU Electrical Engineering, Technical University of DenmarkAmerican Superconductor (AMSC)SeaTitan 10MW• HTS – Superconducting field winding• Copper armature winding• Generator diameter: 4.5–5 meters• Weight: 150-180 tonnes (55-66Nm/kg)• Efficiency at rated load: 96%• Challenge– HTS price and availability• Advantage– Relatively simple cooling systemwith off-the-shelf solutions– Cooling powerReproduced with permission from AMSCHighest torque HTS machine intended for ship propulsion:• 36.5MW @ 120rpm• 2.9MNm @ 75 tons• 39Nm/kg18/04/2012Development of Superconducting Wind Turbines23 DTU Electrical Engineering, Technical University of DenmarkGeneral Electric (GE)10-15MW • LTS – Superconducting field winding• Extensive experience from the MRI sector• Rotating armature• Challenge– Complicated cooling system and higher cooling power• Advantage– Proven technology from MRI– Cheaper superconductorReproduced with permission from GE18/04/2012Development of Superconducting Wind Turbines24 DTU Electrical Engineering, Technical University of DenmarkAdvanced Magnet Lab (AML)10MW fully superconducting• MgB2 – Fully superconducting generator• Superconducting field winding• Superconducting armature winding• Challenge– Complicated cooling system and higher cooling power– Improvement in MgB2 wire isneeded– AC losses• Advantage– Cheap superconductor– Fully superconducting– More torque denseReproduced with permission from AMLVBATTP  ,18/04/2012Development of Superconducting Wind Turbines25 DTU Electrical Engineering, Technical University of DenmarkPatent Development• Web of Knowledge search with keywords: “Supercond*” and “machin*”26 DTU Electrical Engineering, Technical University of DenmarkDiscussion and conclusion • Superconducting generators might be the answer to large wind turbines– Smaller generator– Less RE demand by a three orders of magnitude• A collaborative effort is needed including:– Wire manufacturers– Wind turbine manufacturers– Wind turbine operators• Large-scale demonstrators are needed– To test the performance in a wind turbine– To test the reliability18/04/2012Development of Superconducting Wind Turbines27 DTU Electrical Engineering, Technical University of DenmarkContinue research at universities• Building small scale prototypes• Learning from these and extrapolating to large scale18/04/2012Development of Superconducting Wind Turbines28 DTU Electrical Engineering, Technical University of DenmarkResults for a simple prototype29 DTU Electrical Engineering, Technical University of DenmarkTHANK YOU!QUESTIONS?

Advantages and Challenges of Superconducting Wind Turbine Generators

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Advantages and Challenges of Superconducting Wind Turbine Generators

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