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TOV NORD SysTec GmbH & Co. KGDivision Energy and Systems TechnologyCertification Body for Wind Turbines

T u V ' : ; ; ; ; ; ; ;Hamburg, 2010-01-15

Certification Reportof the wind turbine

WESpe, rotor blade CK220, hub height 15.5 m,IEC 61400-2 (2006) Class IIA

- Load Assumptions -

ruv NORD Report No.: 8000 191 344/1 E Rev.1Subject of assessment: Load assumptions for the wind turbine WESpe, rotor

blade CK220, HH 15.5 m concerning theIEC 61400-2 (2006) Class IIAManufacturer: WES IBS GmbHOsterstrasse 15

25693 St. MichaelisdonnGermanyDocumentation prepared by: Windrad Engineering GmbHMollisstrasse 10

18209 Bad DoberanGermany

This Certification Report comprises 10 pages.

Rev. Date Changes0 2009-08-10 First edition1 2010-01-15 Changes on tower design, pitch control, power curve, brake application, 'gear box and bearing

TOV NORD CERT Certification Body for Wind Turbines Langemarckstr.20 45141 Essen fonlfax (Hamburg) +49 (0)40 8557 2417 I .. , 2552

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Page 2Certification Report of the wind turbine WESpe, rotor blade CK220, HH 15.5 m,IEC 61400-2 (2006) Class IIA -Load Assumptions-2010-01-15, TOV NORD Report No.: 8000 191 344/1 E Rev.1

1 Documents1.1 Documents reviewed1.1.1 Lasten fur KWEA WESpe nach EN 61400-2 (IEC 2) DIBTKlasse 4

Doc.-Name: R_095_001_Lasten5mRotor_R5,Rev. 5, 11.11.09

1.2 Pertinent documents1.2.1 Maschinentrager Getriebe, 6225WEA5K-02.00

Dok.-Name: 6225-02.00 Maschinentraeger Getriebe.idw.pdf,Rev. 1, 01.07.081.2.2 Rotor 100 4.5m, 6225WEA5K.5-03.00Dok.-Name: 6225-03.00 Rotor 5.pdf

Rev. 1,01.07.081.2.3 Sicherheitskonzept der WESpeDok.-Name: Sicherheitskonzept WESpe.pdf

15.03.091.2.4 BlattanschluB 100 LK150, 6225WEAK.5-03.03

Dok.-Name: 6225-03.03 Blattanschluss.pdfRev. 1, 01.07.08

1.3 Applied standards1.3.1 DIN EN 61400-2

Windenergieanlagen - Teil 2: Sicherheit kleiner Windenergieanlagen(IEC 61400-2, Ausgabe 1996)Januar1998

i

1.3.2 IEC 61400-2 Edition 2Wind Turbines - Part 2: Design requirements for small wind turbinesEdition 2006

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T u V ' : ; ; ; ; ; ; ;2 DescriptionThe small wind turbine WESpe has a lee side four bladed upwind rotor with a passivyaw system. The power is rated by a passiv regulation of all four rotor blades, which aretwisted subject to the rotor speed along the centre line. The wind turbine is mounted ontop of a two-parted, braced tubular tower with a height of 15.0 m, i.e. a hub height of15.5 m incl. foundation.The basic technical parameters of the wind turbine can be taken from the following ta-ble 2.1.Table 2.1: Technical main data of the wind turbine WESpe, wind speeds related

to hub heightrated power 5.0 kWhub height 15.5 mrotor diameter 5.0 mrated rotor speed 155 rpmrated variable rotor speed range 75.0 - 160 rpmactivate rotor speed of safety system 170 rpmGearbox ratio 9.8rotor overhang (in front of tower axis) 0.66 mtilt angle 0rotor cone angle 10cut in wind speed 4.0 rn/srated wind speed 11.0 m/scut out wind speed (1O-minute average) 20.0 m/saerodynamic blade airfoil CK220blade mass 10.84 kgblade pitch adjustment range 0 to _39hub mass (incl. blade bearings and generator rotor) 66.4 kgnacelle mass (incl. generator stator, without hub and 190 kgblades)nacelle centre of mass (in front of tower axis) 0.23 mdesign lifetime 20 years

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3 Calculations conducted by the manufacturer3.1 Principle dataIn order to determine the loads Windrad has set up a three-dimensional calculationmodel for the wind turbine WESpe taking into account the dynamics and the aeroelas-ticity of the plant.All calculations were conducted using the program FLEX5.The calculation model takes into account all mass and stiffness contributions relevantfor the vibration behaviour of the wind turbine, as well as the pitch and power converterregulation and all load relevant characteristics of the operation and safety system rele-vant for the loads (see /1.1.1/ + /1.2.3/).Instead of the braced tubular tower an alternative tower is used for the load calculationswhich has the same first and second eigenfrequency as the braced tower. The towerbase loads as well as the foundation loads will be proved separately with the tower toploads determined in /1.1.11. These loads are not part of this assessment.The load calculations are conducted taking into consideration a stiff restraint of thetower bottom.The calculation of loads for the wind turbine takes place according to the requirementsof the DIN EN 61400-2 (1998) /1.3.1/ class IIA and of the IEC guide line 61400-2 (2006)/1.3.2/ for class IIA under the assumption of the most unfavourable conditions in eachcase.Table 3.1.1 shows the wind speeds at hub height 15.5 m, which form the base of thedesign calculations of the wind turbine.

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Table 3.1.1: Wind speeds at hub height 15.5 mDIN EN I lEG IIA

Annual average wind speed (600 s average) 8.5 mlsExtreme 1-year wind speed 34.0 mlsExtreme 50-year wind speed 42.5 mlsExtreme 1-year gust wind speed 44.6 mlsExtreme 50-year gust wind speed 59.5 mls I

For the 1st natural frequency of the rotor blades (standing rotor) and for the 1st and 2ndnatural frequency of the tower the values are denoted in the table 3.1.2:Table 3.1.2: Natural frequencies of the WTG WESpe CK220Blade, flapwise 1. NF 10.08 HzTower, bending (fore-aft) 1. NF 3.11 HzTower, bending (fore-aft) 2.NF 5.90 HzTower, bending (side-side) 1. NF 3.11 HzTower, bending (side-side) 2. NF 5.90 Hz

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3.2 Fatigue loadsThe fatigue loads are determined in consideration of the wind turbines dynamics, theaeroelastic coupling and a three-dimensional wind turbulence by means of numericalsimulations.The load calculation of the power production load cases is conducted for 9 differentwind speed intervals at mean wind speeds between 4.0 m ls and 20.0 m ls and an inter-val width of 2 m/s. The simulation time is 600 s in all calculations. The incoming flow issimulated to approach the wind turbine at an angle of 8 as well as 0 lateral to the rotoraxis.The setting up of the load collectives takes place in 11.1.11 for a mean annual windspeed of 8.5 m ls at hub height - covering wind zone II according to 11.3.11 and 11.3 .2 1 -whereas the statistical distribution of the mean wind speeds is assumed to fit aRayleigh distribution. The design lifetime is 20 years.The fatigue load collective is determined by the design situations "power production","power production plus occurrence of fault", "shut down" and "parking" according to11.3.11 and 11.3.2/.The fatigue loads are reported in 11.1.11 at the following cross sections:

Blade: blade connectionTower: Tower TopHub: rotatingMain bearing: fixed

The load-cycle ranges of the time series are counted by means of the rainflow countmethod. The fatigue loads are presented as damage equivalent loads for all cross sec-tions given above as well as load duration distribution for main bearing.The damage equivalent loads are determined for the exponents 3-12 of the Wohlercurves and for an equivalent cycle number of 1.0x1 07.For the determination of the fatigue loads a safety factor Yf = 1.0 is assumed.

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Page 7Certification Report of the wind turbine WESpe, rotor blade CK220, HH 15.5 m,IEC 61400-2 (2006) Class IIA -Load Assumptions-2010-01-15, TOV NORD Report No.: 8000 19134411 E Rev.1

3.3 Extreme loadsThe calculation of the extreme loads is conducted for all load case categories of thesynoptical table of /1.3.2/ for an aeroelastic model.The most unfavourable wind speeds and wind direction changes according to DINEN IIA /1.3.1/ and according to lEe we IIA /1.3.2/ were used in the calculations. Theapplied extreme wind speeds are listed in table 3.1.1.The extreme loads are determined at the same cross sections as the fatigue loads (see3.2). The load safety factor is chosen accordingly to the value prescribed in /1.3.2/ asSF = 1.35.The extreme loads are listed in tables with application of the safety factors.Since no maintenance work is done on the built-on turbine, the calculation for mainte-nance loads is omittedIn order to verify the blade-tower clearance the maximum blade deflection in tower di-rection of all load cases is recorded. The distance of the loaded blade tip to the towersurface amounts to 0.955 m (excl. SF). The distance of the unloaded blade to towersurface is 1.0 m.

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4 Extent of examinationsThe masses, moments of inertia, stiffnesses, airfoil data and wind speeds used byWES in the presented simulation files were checked with respect to plausibility and alsoassumed to be correct.The aerodynamic properties and the mass and stiffness distribution of the rotor bladesas well as the elastic properties of the tower were modelled according to the data pro-vided by the manufacturer in 11.1.1 I .

IIThe numerical examination was conducted by means of independent calculations usingthe program "SAMCEF for Wind Turbines" Version 2.0 from SAMTECH ..For the purpose of checking the operating loads the range of wind speeds under con-sideration (4.0 mls to 20.0 mIs, related to hub height) was divided into 9 wind speedintervals with an interval width of 2 m/s. The turbulence intensity in the longitudinal di-rection was assumed to be 34.5 % - 16.5 % 11.3.2/ . The improved Karman turbulencemodel was applied for the longitudinal, lateral and vertical direction. The simulation timefor each wind speed interval was 600 s. All extreme loads required by 1 1.3 .1 /a nd 1 1. 3.2 1were included in the evaluations. The time series were extrapolated to the design life-time of 20 years assuming a Rayleigh distribution of wind speeds. Counting of the loadcollectives was accomplished by means of the rainflow count method.For the purpose of checking the extreme loads independent simulation calculationswere conducted in an appropriate extent and results were compared with the calcula-tions submitted by the manufacturer. The evaluation was done at the following compo-nents and positions: tower top, hub rotating) and blade root.

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Page 9Certification Report of the wind turbine WESpe, rotor blade CK220, HH 15.5 rn,IEC 61400-2 (2006) Class IIA -Load Assumptions-2010-01-15, TOV NORD Report No.: 8000 191 344/1 E Rev.1

TuV~

5 Conditions/Instructions5.1 It must be ensured and documented by the manufacturer that the system pa-rameters used in the simulations are in accordance with those in the componentslist within technical tolerances. This applies with regard to masses, centres of

gravity and stiffnesses used. Additionally for the rotor blades this also concernsprofile data and the balance situation of the overall rotor.

L5.2 In case of deviations greater than 5% from the determined first natural tower

frequency a recalculation of the loads under observance of the actual naturaltower frequencies will be necessary.

5.3 Influences by extreme exposure of temperature were not considered.

5.4 The calculated load assumptions have to be validated with measured loads ac-cording to the lEG 11.3.2/.

5.5 In the case of influence of nearby buildings a local increase of the turbulenceintensity may arise, which leads to higher plant loads. This should be consideredaccording to 11.3.21 when the wind turbine is to be erected e.g. inside a windfarm.

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6 Results of examinationFor the wind turbine WESpe, CK220 with a hub height of 15.5 m the calculations of themanufacturer have been carried out according to the DIN EN class IIA /1.3.1/ and ac-cording to the IEC guideline IIA /1.3.2/. Load assumptions and loads can be assumedas correct in consideration of the above mentioned conditions/instructions and can beused as a basis for the type approval.In detail the following loads submitted in the document /1.1.1/ are confirmed:Fatigue loads /1.1.1/:Damage equivalent loads:LDDs:

Page 26 - 27Page 27 - 28Extreme loads /1 .1.1/:Tower top:Rotor blades:Hub:Main bearing:

Table on page 25Table on page 23Table on page 24Table on page 24

All data and results of the under /1.1/ reviewed documents and data storage mediumsare released in consideration of the conditions in point 5 for further usage.The extreme and the fatigue loads were evaluated in the calculation coordinate sys-tems described in /1.1.1/.With the maximum tip deflection in front of the tower surface a minimal distance of0.91 m (incl. safety factor for loads and material of 1.35 * 1.1 = 1.485) is reached,whereby no interference between blade and tower occurs. With this the condition of/1.3.2/ is fulfilled.

The approved document /1.1.1/ was annotated with check notes and date stamps.

Expert in charge: Released:

~~lJ0~Dipl.-Ing. Werner Petruschkeipl.-Technomath. Katja Gotz