1. Staffan Engström, Ägir Konsult AB Stefan Lindgren, VG Power AB
Design of NewGen Direct-Drive Generator for Demonstration in a 3,5 MW Wind Turbine
Staffan Engström, Ägir Konsult AB
Stefan Lindgren, VG Power AB

2. VG Power AB, Västerås, Sweden
Founded in 2002
Today 60 mostly ex-ABB employees.
Specialists in large scale hydropower rehabilitation and service
Full expertise in electrical and mechanical calculation and design of generator equipment
Voith Siemens Hydro is majority owner

3. Ägir konsult, Lidingö, Sweden
Consultant in wind power technology and siting.
Originator of the NewGen electrical generator

4. Demonstration project
GOALS
1. To develop a 3.5 MW generator, test in lab together with electrical converter equipment
2. Demo project with generator in a wind turbine based on existing design, field test, routine operation
Financial support from the EU and from Energimyndigheten, Sweden
Wind turbine to be erected at Vattenfalls’s test site at Näsudden, Gotland

5. Partners in project
VG Power, Sweden Generator
Scanwind, Norway Wind turbine
Verteco, Finland Frequency converter
SKF, Sweden Wheels and bearings
Teknikgruppen, Sweden Analysis and evaluation

6. Scanwind 3 MW wind turbine at Hundhammerfjell, Norway

7. Project milestones
Project start May 2007
Generator design completed May 2008
Manufacture, workshop testing completed July 2009
Wind turbine erected October 2009
Commissioning completed January 2010

8. The largest wind turbine suppliers during 2006
Market - wind turbines
The largest wind turbine suppliers during 2006
Direct drive
Source BTM Consult

9. Reference technology – Enercon
Extremely heavy due to stiffness requirements
4,5 MW ton generator weight
See man for comparison!

10. Large diameter beneficial for amount of active material
The amount of electrically and magnetically active material decreases with increased air gap diameter.
Weight
Diameter

11. … but not for the structure (in conventional design)
With conventional design the weight of the structure increases rapidly with diameter
High total weight
Relatively small optimal diameter
Weight
Diameter

12. Schematic picture of conventional direct driven generator
Air gap ca 5 mm, tolerance ca 0,5 mm.
Long load path means a heavy design due to stiffness requirement

13. Schematic picture of NewGen
Generator bearings adjacent to the air-gap
Minimised load-path and stiffness need
Which reduces need for construction material
And enables further increase of diameter
With further reduced need for electrical material

14. Overview NewGen (1)
Rotor and stator form two narrow rings
Push-pull rods for low stator weight
Weight 37 tons, 70% less than conven-tional 4 MW, 19 rpm

15. Overview NewGen (2)

16. Cross section NewGen
Outside rotor of solid steel with Neodym magnets
Pairs of steel wheels support rotor
Stator with conventional windings

17. NewGen installation
Extremely low weight
Extremely short - ca 0.7 m (4 MW)
Direct rotor/hub connection - saves weight also in hub
Wide generator body benefits aerodynamics
Mechanical brake possible to integrate in generator

18. Weight of alternative 3 MW 15 rpm drive train solutions

19. Pilot generator in relation to full scale (4 MW)
Same peripheral speed
Same wheel diameter
Half active length
1/5 diameter
1/30 power

20. Pilot generator ready for testing (July 2004)

21. The pilot generator stator before winding (April 2004)

22. Winding the pilot generator (April 2004)

23. Stator with bearing wheels (June 2004)

24. Assembly completed (June 2004)

25. Detail of wheels and race (June 2004)

26. Testing the pilot generator (July-August 2004)
Test test up:
DC machine
Gear-box
Pilot generator

27. Test programme
Conventional
Measurement of winding resistance
Idling without magnets (measurement of friction)
Idling with magnets (voltage as a function of rpm)
Short circuit tests, at reduced rpm
Endurance test at full power
Idling with magnets (check of no change)

28. Test results
Runs smoothly, little noise
Little friction (130 watts at rated rpm)
Low winding temperatures
Top efficiency 96,7% at half power
Full power efficiency 94,9%

29. Efficiency measurement, at 100 rpm
1,0 p.u. = 140 kW

30. Main voltage at idling, 100 rpm

31. Summary – the offer of the NewGen concept
Benefits of direct drive
Weight and installation cost as geared solution
Well proven design of electrical and magnetic active components
Mechanical design with wheels and bearings based on in-house railway technology
Reliability comparable with in-house hydro technology
Feasible for large wind turbines - 20 MW
Excellent experience from designing, building and testing the 140 kW pilot scale NewGen
Ongoing 3.5 MW demo project