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

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

Scanwind 3 MW wind turbine at Hundhammerfjell, Norway

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

The largest wind turbine suppliers during 2006 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 The amount of electrically and magnetically active material decreases with increased air gap diameter. Weight Diameter

… 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

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

Overview NewGen (2)

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

Weight of alternative 3 MW 15 rpm drive train solutions

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

Pilot generator ready for testing (July 2004)

The pilot generator stator before winding (April 2004)

Winding the pilot generator (April 2004)

Stator with bearing wheels (June 2004)

Assembly completed (June 2004)

Detail of wheels and race (June 2004)

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

Main voltage at idling, 100 rpm

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