On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid wind turbine tonalities

Transcription

1 Ben Marrant, Fred Vanhollebeke IW ZF Friedrichshafen AG MOTION AND MOBILITY On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid wind turbine tonalities

2 Agenda 1. Introduction 2. Wind turbine sound sources 3. Wind turbine mechanical sound 4. Avoiding mechanical sound by design optimization 5. Conclusion 6. Challenges IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

3 Introduction Tonality-free gearbox stated as requirement in gearbox design specification Wind turbine tonalities measured in validation phase costly redesigns and fewer design options Tonality prediction should be done in concept phase more and cheaper design options Product development process in case of Changes Influence Required resources Information Time IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

4 Wind turbine sound - Aeroacoustic sound Generated by aero-elastic interaction between: air rotating blades tower nacelle Determines overall level Radiates directly to the surroundings Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

5 Wind turbine sound - Aeroacoustic sound Generated by aero-elastic interaction between: air rotating blades tower nacelle Determines overall level Radiates directly to the surroundings Broadband by nature Several noise mechanisms Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

6 Sound power level [db(a)] Wind turbine sound - Mechanical sound Originates from mechanical components such as gearbox, generator, fans, Tonal by nature and only audible when protruding aero-acoustic sound Airborne sound: radiated from gearbox ~10 % of the cases Structure borne sound: radiated from wind turbine ~90 % of the cases Total SPL of 3MW gearbox at rated power = 92 db(a) 110,0 100,0 90,0 80,0 70,0 60,0 50,0 40,0 30, Frequency [Hz] Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

7 A-weighted sound pressure Wind turbine sound - Mechanical sound - Challenges Wind turbines installed closer to urbanised areas => increase in sound pressure Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

8 A-weighted sound pressure Wind turbine sound - Mechanical sound - Challenges Wind turbines installed closer to urbanised areas => increase in sound pressure More stringent limits on total sound and tonal levels Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

9 A-weighted sound pressure Wind turbine sound - Mechanical sound - Challenges Wind turbines installed closer to urbanised areas => increase in sound pressure More stringent limits on total sound and tonal levels Optimised blade design Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

10 A-weighted sound pressure Wind turbine sound - Mechanical sound - Challenges Wind turbines installed closer to urbanised areas => increase in sound pressure More stringent limits on total sound and tonal levels Optimised blade design Low sound operating modes Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

11 A-weighted sound pressure Wind turbine sound - Mechanical sound - Challenges Wind turbines installed closer to urbanised areas => increase in sound pressure More stringent limits on total sound and tonal levels Optimised blade design Low sound operating modes Tonal sound evaluation at very low wind speeds Petitjean et al. (2011) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

12 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

13 Wind turbine mechanical sound Historical way of thinking High gearbox vibration levels cause tonalities All vibration levels well below 1 mm/s versus Experimental validation GBX torque arm vibration levels in vertical direction, measured in Wind Turbine No direct link between high vibration levels and tonality Highest vibration level produces no tonality Low/intermediate vibration level causes tonality => High gearbox vibration levels are not necessarily root cause of tonality IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

14 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

15 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

16 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

17 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

18 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

19 Wind turbine mechanical sound Historical way of thinking versus Experimental validation NOISE SOURCE Gearbox: gear excitation Gearbox: resonances TRANSFER PATH Wind turbine: drive train and other structural parts Wind turbine: radiating parts RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

20 Wind turbine mechanical sound Historical way of thinking NOISE SOURCE TRANSFER PATH Gearbox: gear excitation Gearbox: resonances Wind turbine: drive train and other structural parts Wind turbine: radiating parts versus Experimental validation Experimental measurements show: Significant coupling between dynamic behaviour of both gearbox and wind turbine structure RECEIVER Tonality outside IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

21 Wind turbine mechanical sound Current way of thinking by Experimental validation NOISE SOURCE Gearbox: gear excitation Resonances: gearbox + drive train + structural parts Experimental measurements show: Significant coupling between dynamic behaviour of both gearbox and wind turbine structure TRANSFER PATH RECEIVER Wind turbine: radiating parts Tonality outside Resonances are influenced by Gearbox design Wind turbine design & Resonances should be tackled by following a system based approach - a component approach alone will not be successful IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

22 Wind turbine mechanical sound Current way of thinking by Experimental validation Resonances are influenced by Gearbox design and Wind turbine design: Test set-up at gearbox supplier cannot be used for predictions of wind turbine drive train dynamics: main propagation mechanism is structure borne sound Wind turbine main frame and cassette system of test set-up are different Wind turbine drive train and test set-up drive train are different Differences in mode shapes Frequency shift between similar mode shapes Gearbox in wind turbine and test set-up loaded differently (e.g. influence of rotor weight) linearization state will be different IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

23 Avoiding mechanical sound by design optimization Strategy Tonalities are caused by interference of gearbox/drive train modes and wind turbine modes tonalities are not caused by very local resonances: global eigenmodes require attention Gearbox/drivetrain: torsional modes, gearbox flexible modes, Wind turbine: eigenmodes of the main frame (bending, torsion), System approach is required Wind turbine model is absolute necessity for assessing gearbox dynamics: Mutual influence of gearbox and wind turbine drive train Dynamic tailoring of the gearbox with respect to wind turbine dynamics IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

24 Avoiding mechanical sound by design optimization Gearbox model Flexible planet carrier assembly: reduced FE model Flexible shafts: reduced FE model Gears: Rigid bodies FE 225 Flexible housing assembly: reduced FE model Accelerometer master nodes Bearings: Linearized stiffnesses: 6x6 matrices Approximated inertias IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

25 Avoiding mechanical sound by design optimization Model validation Multi-level approach: Modelling in small sequential steps Experimental validation in sequential steps Implementation: Multi body approach Finite elements IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

26 Avoiding mechanical sound by design optimization Model validation - Experimental validation of gearbox Dynamic behaviour of complete gearbox assembly (Red = measurement, blue = model, exported as wireframe) IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

27 Avoiding mechanical sound by design optimization Model validation - Experimental validation of gearbox Frequency range [Hz] # modes # correlated [%] MAC [%] % 94% 3% % 74% 2% % 76% 5% % 70% 3% % 61% 1% % 45% 9% % 67% 2% % 61% 7% % 54% 6% Frequency difference [%] IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

28 Avoiding mechanical sound by design optimization Model validation - Experimental validation of gearbox Gearbox housing is dominant for large part of dynamic behaviour Individual castings dominate certain frequency range Very good correlation with experiments up to 300 Hz Acceptable correlation with experiments between 300 Hz and 500 Hz IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

29 Avoiding mechanical sound by design optimization Model validation - Conclusion Extensive technology projects made sure that gearbox models are well validated: KRATOS (Flemish project) ALARM (European project, Eureca label) Multiple customer projects... Wind turbine models need to have the same level of confidence in order to make good predictions of tonality risk in design phase IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

30 Avoiding mechanical sound by design optimization Evaluation of wind turbine dynamics Optimisation example in design phase: Bending mode close to nominal operating point of wind turbine Gearbox housing dominant in this eigenmode Suggested change: additional ribs on bearing housings IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

31 Avoiding mechanical sound by design optimization Evaluation of wind turbine dynamics Optimisation example in design phase: IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

32 Avoiding mechanical sound by design optimization Evaluation of wind turbine dynamics Optimisation example in design phase: IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

33 Evaluation of wind turbine dynamics Evaluation of wind turbine dynamics Simulated FRF s from gear mesh to velocities of various : Rotor blade locations using system model Tower locations Source: gear mesh, (bearings, pumps) Structure borne transfer path inside / outside gearbox Airborne radiation by gearbox / by other components IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

34 Evaluation of wind turbine dynamics Evaluation of wind turbine dynamics Troubleshooting in prototype validation phase: IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

35 Conclusion Dynamics determined by coupled system behavior Wind turbine tonal behavior can already be assessed in concept and design phase System based approach required already in concept phase Dynamic tailoring of gearbox w.r.t. wind turbine dynamics Open cooperation is absolute necessity IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

36 Challenges Complexity of wind turbine models huge amount of eigenmodes should be taken into account Efficient evaluation of potential risks linear domain analysis: potential energy vs. kinetic energy Non-linear system behavior: Tonality depending on torque Aero-acoustic background noise depending on wind speed Efficient acoustic models are required Difficulties to asses absolute vibration levels due to inaccurate implementation of: Gear excitation lack of suitable direct measurement techniques for validation Damping IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid

37 Thank you ZF Friedrichshafen AG behält sich sämtliche Rechte an den gezeigten technischen Informationen einschließlich der Rechte zur Hinterlegung von Schutzrechtsanmeldungen und an daraus entstehenden Schutzrechten im In- und Ausland vor IW, On the necessity of open cooperation between gearbox supplier and wind turbine OEM to avoid ZF Friedrichshafen AG reserves all rights regarding the shown technical information including the right to file industrial property right applications and the industrial property rights resulting from these in Germany and abroad.