Wake Conference 2017 Uppsala,

Transcription

1 Wake Conference 2017 Uppsala, Modelling of Wind Turbine Loads nearby a Wind Farm Alexander Werkmeister, M.Sc. Prof. Dr.-Ing. Georg Jacobs, Prof. Dr.-Ing. Ralf Schelenz

2 Outline Motivation Site Assessment Reference Turbine Results 2

3 Motivation Increasing production of offshore wind energy 3

4 Wind farm Grid connection Motivation Offshore space is regulated and limited Captured Wake at SWiFT Facility (Sandia) Operational Under Construction Approved Applied FINO-1 + Alpha Ventus (60 MW) Source: (/2017) Source: Informationssystem/ContisKarten/NordseeOffshoreWindparksPilotgebiete.pdf (2017) 4

5 Site Assessment: FINO-1 Offshore measurement mast nearby Alpha-Ventus FINO-1 constructed: 2003 Alpha Ventus in operation: 2010 Possible to observe difference due to wind farm Wind direction distribution [%] Wind resource at 80 m Source: Federal Maritime and Hydrographic Agency, FINO-1 Research Platform database, ( (accessed ) 5

6 Site Assessment: FINO-1 + Alpha Ventus FINO-1 can be used to determine wake influences Increase of turbulence intensity by factor 3 6

7 Site Assessment: FINO-1 + Alpha Ventus FINO-1 spaced close to WT 4 Higher TI than Design Case 7

8 Site Assessment: Wind field 8

9 Site Assessment: Inflow conditions Combination of wind rose and TI as weighted year inflow 9

10 Reference Turbine: C3x126 Verified MBS model Four-point suspension 3 stage gearbox Modular design D.F.I.G. Offshore tower 126m NREL reference-rotor Technical data Rotor diameter Tower height 126 m 112 m Nominal rpm 11 min -1 Nominal power 3 MW i gearbox Cut-in Cut-out 3 m/s 25 m/s 10

11 Modeling of C3x126 through Multi-Body-Simulation 11

12 In-plane force F y,lower [N] Load cycles [-] Load Condition of C3x126 IEC DLC 1.1 Inflow A (TI = 5%) Inflow B (TI = 10%) Inflow C (TI = 15%) For all wind speeds z x y Rain flow count over a year Inflow A (TI = 5%) Inflow B (TI = 10%) Inflow C (TI = 15%) In-plane force F y,upper [N] 12

13 Results Investigation of influence between TI = 5% and 15% Simplifying rain flow count over a year through the use of mean stress Only variations in in-plane excitations Major changes at low load cycles (< below 10 6 load cycles) Amplitude at low load cycles increased by 20% Fatigue relevant 13

14 Wake influence based on Weibull distributions Combined Inflow: Combination of TIs (5%; 10% and 15%) and corresponding Weibull distribution Comparison of different loadings through inspection of dynamic equivalent load DEL = S i k with k = 3, N eq = Without wake effect Combined Inflow Load cycle Pitching torque N My 13 MNm 32 MNm Load cycle Yawing torque N Mz 12 MNm 33 MNm N i N eq 1 k 14

15 Conclusion and Outlook Wake effect have high influence on in-plane force and moments Increase of dynamic equivalent load by factor 2.5 In further studies: Investigation of partial wake effects 15