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Possible solutions to overcome drawbacks of d irect-drive generators for large wind turbines

Possible solutions to overcome drawbacks of d irect-drive generators for large wind turbines. Deok-je Bang , Henk Polinder , Ghanshyam Shrestha , Jan Abraham Ferreira Electrical Energy Conversion, DUWIND Delft University of Technology The Netherlands d.j.bang@tudelft.nl. Background.

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Possible solutions to overcome drawbacks of d irect-drive generators for large wind turbines

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  1. Possible solutions to overcome drawbacks of direct-drive generators for large wind turbines Deok-je Bang , Henk Polinder , Ghanshyam Shrestha , Jan Abraham Ferreira Electrical Energy Conversion, DUWIND Delft University of Technology The Netherlands d.j.bang@tudelft.nl

  2. Background Increasing Wind Turbine power, Direct-drive generator is large & heavy. Hence, it is expensive. For large direct-drive generators,  New configuration with high force density and less materialis required. Hence, the cost reduction is achieved.

  3. Electromagnetic material Structural material Objective • Find solutions of large direct-drive generators

  4. Contents • Promising solutions for large direct-drive • Challenges of large direct-drive • Rough design of new direct-drive PM generators • Prototype (downscaled) • Summary • Further researches

  5. 1. Promising solutions for large direct-drive (Source: Bang et al. 2008) • Active part • Permanent magnet synchronous generator (PMSG) • Inactive part • Ring shaped construction of which air gap is maintained by the bearingless drive • Practical issues • Modular construction for easy production, handling and maintenance

  6. 2. Challenges of large direct-drive • Minimize inactive material (1) New ring shaped construction

  7. (2) New bearingless drive

  8. New supporting and guiding concept (1) Buoyant rotating part in order to • Support heavy structure easily • Reduce structural material for supporting • Give flexibility in supporting and guiding heavy structure

  9. (2) Hydrostatic bearing in order to • Prevent the touchdown of rotor on stator • Maintain the air gap when the bearingless drive is in failure • Reduce a peak power consumption of the bearingless drive

  10. 3. Rough design of new direct-drive PM generators:5 & 10 MW

  11. Active mass

  12. for the deflection modelling of rotating part Inactive mass Assumption: • Max. normal pressure acting on rotor & stator is about 325 [kN/m2] • Deflection < 10% of g • Deflection of stationary part is neglected • th and tb of stationary part are the same with rotating part’s

  13. Modeling of rotor deflection: Mass estimation:

  14. Total mass estimation Assumption:m/T of each concept is constant in scaling up. • Concept-1: EESG DD • (Enercon concept, m/T=66.5 kg/kNm at 4.5 MW) • Concept-2: PMSG DD • (Zephyros concept, m/T=46.4 kg/kNm at 1.5 MW) • Concept-3: PMSG DD • (Theoretical design, m/T=25 kg/kNm at 2, 3 & 5 MW) • Concept-4: PMSG DD • (NewGen concept, m/T=18.4 kg/kNm at 4 MW) • Concept-5: DFIG 3G • (DFIG concept, m/T=17.4 kg/kNm at 3.5(4) MW)

  15. Generator mass comparison of different concepts In the rough design, general steel structure was used for inactive part construction. Therefore it is expected that the inactive mass can be reduced further by structural optimization.

  16. 4. Prototype (downscaled) • Modular construction (machine type: TFPM machine) • Ring shaped construction : Sponsored by Wintech in Korea Rotor Stator Rotor 3ph_1set Stator Rollers

  17. Experimental setup Pulley & Belt • Experimental analysis is going on.

  18. 5. Summary • New direct-drive concepts have been proposed with - New bearingless drive concept - New guiding/supporting concepts • Rough design of new 5 & 10 MW direct-drive PM generators have been done • Downscaled prototype has been built - Structure: Ring shaped, doubled-sided AF machine - Machine type: (TF)PM machine

  19. ? ? Steel Al. profile 6. Further researches • Electromagnetic optimization • Detailed design on the new direct-drive concept • Structural mass minimization • Find sealing solution

  20. Thanks for your attention !

  21. Back up slides

  22. Source: Dubois (2004), Ph.D. Dissertation Promising solutions for large direct-drive (Source: Bang et al. 2008) • Active part • Permanent magnet synchronous generator (PMSG) • Inactive part • Ring shaped construction of which air gap is maintained by the bearingless drive • Practical issues • Modular construction for easy production, handling and maintenance

  23. Direct-drive permanent magnet synchronous generator (PMSG DD) Strength of PM machine • high energy yield and light weight • no additional power supply for the field excitation • improvement in the efficiency • higher reliability without slip rings • higher power/weight ratio compared to EE machines

  24. Inactive part (proposed in 2008)

  25. Conventional bearingless drive Concept with complicated winding and control

  26. New bearingless drive

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