Development and operating experience of

the WEC Winwind WWD-1

G.Böhmeke, WINWIND OY

Concept origin

Direct drives appeared on the market 1994-’95

Comparative study on direct drives, including slow-speed drives with single-stage gearing at aerodyn GmbH in 1996-’97

First publication EWEC ’97 Dublin

Study results, facts...

Direct drive leads to very high generator mass and cost , the machine is not competitive if bought from ready-made components

The situation becomes worse with increasing size

This can only be partially neutralized by making the generator and inverter in large series in the own workshop

A newcomer can not start on this basis

... Facts

Large-scale gearbox failures from 1999 to 2002

Investigations partially confidential. Published results leave many questions open

Damages seem to concentrate on high-speed parts

A newcomer should not take the risk of using a conventional gearbox

Aim

Reliable and competitive wind turbine, suitable also for arctic and remote locations

Concept scaleable up to several MW

Components bought from well-known component deliverers, but own test and assembly

Avoiding all gearbox problems known today

Avoiding the cost and mass problems of direct drives

Solution

Low-speed drive train, planetary gearbox with comparatively slow generator

Gearbox and generator risk analysis and measures against possible problems

Further measures to increase overall reliability

Patents, co-operation, funding

Slow-speed integrated drive train concept called MULTIBRID and patented by aerodyn GmbH

WinWinD and its cooperation partner Pfleiderer Wind Energy GmbH hold the utilisation rights.

Pfleiderers 5MW-MULTIBRID is in parallel under development

TEKES subsidy to WINWIND for the development of the 1MW wind energy converter WWD-1

Founded in March 2000, share company

Largest share holders

Powest Oy, A subsidiary of biggest Finnish power company, Pohjolan Voima Oy

Head Future Technologies Oy, Venture capital company, member of the Head Team

Presently 20 employees, three locations

WinWinD

Location

Workshop, assembly and testIi-Raasakka

Machine design and development Helsinki

Main office and administrationOulu

WWD-1 Main component deliverers

Hub and mainframe casting METSO FOUNDRY

Tower steel RAUTARUUKKI

Inverter ABB

Main bearing HRE

Blades EUROS

Gearbox METSO DRIVES

Generator ABB

WWD-1 drive train

WWD-1 drive train (simplified)

WWD-1 Basic data

Rated power 1 000 kWRotor diameter 56 (60) mClassification IEC 2-A (3-B)Tower height 56 - 70 mCut-in wind speed 3 m/sCut-out wind speed 25 (20)m/sRated wind speed 12.5 m/sTop mass 53 to

Rated rotor speed 25.6 rpmRated gen. speed 146 rpmGear ratio 5.71

Temperature rangeFirst machine (Oulu) -30C to +25CSeries site-specific

WWD-1 Basic dataDiagram from

aerodyn GmbH

0

5

10

15

20

25

30

35

40

45

50

25 35 45 55 65 75 85 95 105 115 125

Durchmesser [m]

rel.

Tu

rmko

pfm

ass

e [k

g/m

²]

GE 3.6 » 268 t

E 30

E 40

E 66

NTK 1500

NTK 300 V 47

V 66

bwu 750

MD 70

leichte WEA

schwere WEA

mk = a * D2.75

Technologie Faktor a = 0.7 to 1.1

N 80

Aeolus II

MOD 5b

M 5000 » 300 t

WWD1

WWD3

E112 ca. 500t

Design rules gearboxBearings and gears

Own crosscheck and neutral expert approvalNo high-speed partsFEM analysis of bearing influence on gearing

Load peaksVariable speed and pitch concept, defined torqueSlip clutch against short circuit torque peaks

Brake dynamics torque peaksBrake acts with only rated torque

Reaction forces and casing deformationsConcentric structure and FEM analysis

Spherical roller bearing problemsOnly cylindrical roller bearings

Oil quality and temperatureAmple cooling and fine filtering

Design rules generatorWinding temperature level

Inherently large surface per kW of lossWater jacket coolingPermanent excitation saves losses and heat

Dielectric winding stress dU/dtAdequate filter

Salt, water, erosionPreformed coil winding, no round-wireNo ambient air through generator

Air gap collisionConventional length/diameter ratio, stiff casingNo direct influence of rotor loads on air gapSensor and supervision

Magnet degradingQuality controlThick glassfibre sleeveCurrent limiting

WWD-1 assembly

WWD-1 back-to-back test

WWD-1 test and running-in

WWD-1 site assembly

WWD-1

August 2001First machine erected in Oulu

April 2003 two units to Kokkola

June 2003 three units To Oulunsalo

September 2003 three units to Kristiinankaupunki

1Q 2004 two units to France

Operational experience...Power curve

As predicted, pitch control needed parameter refinementsNoise

First results Lpa= 103 dBANo measured single tone contentGearbox silent Dominant machine noise is generator slot frequencyNo elastic suspension/insulation needed anywhere

Grid interferenceAs designed and predicted by inverter manufacturerEN-SFS 50160 limits are fulfilled

DynamicsAs designed

... operational experienceSite

Some days of downtime due to rime iceBlade heating system not justifiedGenerator air cooling => water jacket for series machinePreheating procedure needed optimization

Temperature level during operationGearbox oil max. 60C so far, est. 80C with 25C ambientGenerator winding max. 85C so far, est. 100 C

Conclusion No problems related to the drive train concept

Low temperature levels, no unexpected loads,high reliability and long lifetime can be expected.

From WWD-1 to WWD-3

Same drive train concept, but increased gear ratio to cancel the lower rotor speed

Still more compact structure and special measures against structure-born noise

Machine development is under work, prototype scheduled for spring 2004

First machine to be sited near Oulu

WWD-3 preliminary base data

Rated power 3 000 kWRotor diameter 90 mTower height 85-90 mCut-in wind speed 4 m/sCut-out wind speed 25 m/sRated rotor speed 15.9 rpm

Aim: MULTIBRID 1, 3 and 5 MW product family