PERMANENT MAGNET MATERIAL PROPERTY CRITERIA IN WIND POWER APPLICATION 14th of June 2012 1 I The Switch 2011
CONTENTS The Switch Turbine technology Generator types PMG rotor designs for WP Demagnetization risk Usage of magnets in different generator types Other requirements for magnetic circuit in generators Cost reduction options 2 I The Switch 2011
BUSINESS We are setting the standard for modern drive train technology. Currently, we are in close to 20 wind turbine designs and are building the capacity for them. Jukka-Pekka Mäkinen, President and CEO 3 I The Switch 2011
THE SWITCH AREAS OF OPERATION WIND POWER EMERGING BUSINESSES Solar & fuel cell converters Variable speed genset drive trains Industrial electrical drive trains
THE SWITCH DRIVE The soul of every reliable wind turbine 5 I The Switch 2011
LOCATIONS The Switch Silkeborg, Denmark The Switch Hudson, NH, USA The Switch Headquarters Vantaa, Finland The Switch Barcelona, Spain The Switch Vaasa, Finland The Switch Hamburg, Germany The Switch Lappeenranta, Finland The Switch Beijing, China The Switch Gumi-City, Korea The Switch Lu an, Anhui, China The Switch Hangzhou, China Medium Size Electrical Machines Deyang, Sichuan, China The Switch Chennai, India The Switch Hong Kong, China 6 I The Switch 2011
WIND TURBINE Turbine automation Yaw control Pitch control Speed control Torque control Electric drive Traditional wind turbine: Gear + high speed IM Direct drive without gear Source:http://windeis.anl.gov/guide/basics/turbine.html
AN EXAMPLE 1. Cooler 2. Generator 3. Automation 4. Anemometer 5. Coupling 6. Mechanical brake 7. Gearbox 8. Main shaft 9. Yaw gear 10. Machine bed 11. Main bearing 12. Hub control 13. Pitch controller 14. Blade Source: Vestas V82-1.65 MW broshure
TYPICAL POWER CURVE: V82-1.65 MW Source: Vestas V82-1.65 MW broshure
GENERATOR OPTIONS Directly net coupled induction machine Double fed induction generator Electrically excited synchronous generator Permanent magnet synchronous generator
PRODUCT PORTFOLIO 6.0 POWER 5.9 MW/1100rpm 5.0 4.25 MW/16 rpm 5.6 MW/1200rpm 4.0 FD: 3.2 MW/346 rpm 3.3 MW/13 rpm 3.3 MW/365 rpm 3.3 MW/1500 rpm 3.0 3.3 MW/136 rpm 3.3 MW/1000 rpm 3.2 MW/414 rpm 2.7 MW/1000 rpm 2.7 MW/1500 rpm 2.2 MW/1000 rpm 2.2 MW/1500 rpm 2.0 1.65 MW/17 rpm 1.65 MW/150 rpm 1.6 MW/1000 rpm 1.6 MW/1500 rpm 1.1 MW/1000 rpm 1.1 MW/1500 rpm 1.0 1.65 MW/120 rpm 1.4 MW/292 rpm LOW MEDIUM 1000 1500 SPEED
GENERATOR CONSTRUCTION Options Machine construction Inner rotor Outer rotor Turbine technology Low-speed/ Direct driven Mediumspeed Cooling arrangement IP 54 Air/air IP54 Air/water Magnet assembly Surface-mounted magnet modules Surface-mounted magnets Winding Random wound Form wound Voltage Low voltage Medium voltage High-speed IP23 Embedded magnets Litz wire HS MS DD In standard platform Option 12 I The Switch 2011
Efficiency (%) DIRECT-DRIVE GENERATORS 92 Increasing efficiency towards partial loads 90 Best overall drive-train efficiency 88 86 No gearbox, no fast-rotating parts Increased reliability kw Highest torque density due to large cooling area in active parts Mechanical interface design for turbine in co-operation with turbine designer Generator bearing can act as a turbine main bearing Large generator size due to high torque Possibility to integrate break system to generator construction 96 94 0 1000 2000 3000 4000 5000
DIRECT-DRIVE GENERATORS Outer rotor generators 3.3 MW, 13 rpm direct-drive outer rotor generator. Frame size: 3000 1.65 MW direct-drive outer rotor Generator Frame size: 2250
DIRECT-DRIVE GENERATORS Down wind generators 4.25 MW, 16 rpm direct-drive generator in test setup Frame size: 3150
GEARED GENERATORS Medium speed generators 1- or 2-stage gearbox Generator speed is usually 100 to 500 rpm Typically flange mounting between generator and gearbox Integrated drive train with a simplified structural design (FusionDrive ) Lowest nacelle weight Improved total turbine cost effectiveness
GEARED GENERATORS High-speed generators 1000 to 2000 rpm speed range with 3-stage gearboxes Small generator size, high efficiency Stand-alone component Can be used with different turbine designs Rotor has embedded magnets Well protected against centrifugal forces and corrosion Typically leg-mounted Air-to-air or air-to-liquid cooling Easily possible to replace existing DFIG without changing nacelle layout Requires heavy gearbox with high-speed shaft
GEARED GENERATORS High-speed generators 5.9 MW, 1100 rpm Frame size: 710 2.2 MW, 1500 rpm Frame size: 500
ROTOR DESIGN Surface mounted magnets For direct drive and medium-speed generators: Allow the maximum power to be captured from the magnet Maximum flux in air gap Typically protected with a module construction (hermetically sealed) Must be firmly fastened against centrifugal forces 3.3 MW medium-speed generator Magnet modules in an outer rotor direct-drive generator
ROTOR DESIGN Embedded magnets For high-speed generators: Magnets are built inside a sealed corrosion-resistant metal enclosure No threat due to centrifugal forces Hermetic sealing provides protection from the environment (rotor is impregnated) Tangentially multiple magnets / pole 3.3 MW high-speed generator rotor
Magnet grade Most critical raw materials: Neodymium (Nd) mainly to increase remanence flux (together with Praseodym; PrNd ~50 /kg (5/2012) Dysprosium (Dy) to increase coersivity (demag. resistance); FeDy ~550 /kg Terbium (Tb) to increase coersivity; ~1200 /kg Grade Dy PrNd Tb Typical use 4X SH 3...4 % 26...27 % 0 Direct drive 40 UH 5...6 % 25...26 % 1...2 % Medium speed 38 EH 3...4 % 24...25 % 2...3 % High-speed
Raw material sources outside China Case study with nine mines / known recourses Mine Country Location Company 1 Australia Dubbo Alkane Recources Ltd 2 Australia Nolans Arafura Recources Ltd 3 Canada Nechalacho Avalon Rare Metals Inc 4 Canada Hoidas lake Great Western Minerals Group 5 South Africa Steenkampakraal Great Western Minerals Group 6 Greenland Kvaenefjeld Greenland Minerals & Energy Ltd 7 Australia Mt. Weld Lynas 8 USA / Ca Mt. Pass Molycorp Minerals LLC 9 USA / Wo Bear Lodge Rare Element Recources Ltd RE recources in 9 mines (kton): Pr 489 Nd 1606 Tb 20 Dy 104 Sum 2220 3 MW PMG consumes RE-materials (not magnets): - Direct Drive 800 kg - Medium speed 130 kg - High speed 80 kg Generator capasity built with 9 mines recources: DD MS HS PrNd 8980 56125 114292 GW Dy 2628 16425 12483 GW
(E-3) Tesla 250 HS Demagnetization 0 CURVE C2D_13 Flux density / Normal component Path_5 Time (s.) : 0,038 Magnet grade is selected based on the demagnetization -250 TOIM_P12_NL 100 200 300 mm calculation External field 300 200 (E-3) Tesla MS Rotor temperature Typical factors 100 0-99,999 CURVE C2D_5 Flux density / Normal component Path_1 Time (s.) : 26,1E-3 Rated frequency / speed (HS worst DD easiest) Air-gap length -200 mm Tangential tention 3PH_SC_HOT 0 50 100 (E-3) Tesla 700 600 DD 500 400 CURVE C2D_232 Flux density / Normal component Path_1 Time (s.) : 184,799999E-3 300 200 0 50 100 mm Critical level 100 C
Demagnetization risk Typical requirements (worst case): Max ambient temp ~45 C => max rotor temperature Min 12 m/s wind Short circuit in terminal box Against present design criteria says: Places where the above conditions is even theoretically possible are few A short circuit in terminal box or winding would destroy the machine anyway. In case of a short circuit further away cable impedance will restrict the sc-current and field Statistical reasons
Other typical requirements in WP Life time 25 years (< 2% flux reduction) < 1% ( or even < 0.5 %) cogging Magnet shape Skewing Rotor Stator Forming Air-gap shape Asymmetry Rotor poles Stator slots IP54 construction (rotor typically requires air circulation for cooling) Sea environment (salt)
REDUCING MAGNET GRADE (COST) BY DIRECT COOLING WITH INPUT FILTER Typical requirement IP54 => Water jacket (+ air circulation) Internal air circualtion + heat exchanger Replace HEX with Goretex filter and exhaust pipe 10...15 C cooler air for cooling => upgrade or lower grade magnets Is applicable for symmetric or asymmetric cooling arrangement Filter has to be changed every 3...5 years Is not real IP54 Requires change of thinking
Power [%] 140 120 100 80 60 40 20 0 EXAMPLE ON DE-RATING Normally generator is designed for 2.5 MW HS-turbine alternatives Current design Increased power 0 10 20 30 40 50 60 Ambient temperature [ C] worst possible operating conditions that occur very rarely (blue circle = rated point) By lowering the design temp by 10 C, generator would be able to deliver 3.3 MW (green circle = rated point) How often the ambient really exceeds 40 C while there is nearly full wind? In europe once a year?? Now the generator designs are according to such conditions Each drop of ~20 C enables using one grade cheaper magnets
Thank You Äyritie 8 C FI-01510 Vantaa, Finland Tel +358 20 783 8200 Fax +358 20 783 8570 28 I The Switch 2011