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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. VG Power AB, Västerås, Sweden. Founded in 2002 Today 60 mostly ex-ABB employees.
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Design of NewGenDirect-Drive Generator for Demonstration in a 3,5 MW Wind Turbine Staffan Engström, Ägir Konsult AB Stefan Lindgren, VG Power AB
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
Ägir konsult, Lidingö, Sweden • Consultant in wind power technology and siting. • Originator of the NewGen electrical generator
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
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
Project milestones Project startMay 2007 Generator design completed May 2008 Manufacture, workshop testing completed July 2009 Wind turbine erected October 2009 Commissioning completed January 2010
Market - wind turbines • The largest wind turbine suppliers during 2006 Direct drive Source BTM Consult
Reference technology – Enercon • Extremely heavy due to stiffness requirements • 4,5 MW - 220 ton generator weight • See man for comparison!
Large diameter beneficial for amount of active material Weight • The amount of electrically and magnetically active material decreases with increased air gap diameter. Diameter
… but not for the structure (in conventional design) Weight • With conventional design the weight of the structure increases rapidly with diameter • High total weight • Relatively small optimal diameter Diameter
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
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
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
Cross section NewGen • Outside rotor of solid steel with Neodym magnets • Pairs of steel wheels support rotor • Stator with conventional windings
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
Pilot generator in relation to full scale (4 MW) • Same peripheral speed • Same wheel diameter • Half active length • 1/5 diameter • 1/30 power
Testing the pilot generator (July-August 2004) • Test test up: • DC machine • Gear-box • Pilot generator
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)
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%
Efficiency measurement, at 100 rpm 1,0 p.u. = 140 kW
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