wind turbine loading

Wind Turbine Loading Torben J. Larsen [email protected]

SMI Stavanger 2016 Science Meet Industry April 6th Måltidets Hus, Ullandhaug, Stavanger

http://www.norcowe.no/

14 March 2016 DTU Wind Energy, Technical University of Denmark

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Basic loading mechanisms

2 6 April, 2016

Loads without turbulence, 10m/s 5MW

Mflap

Medge

Mtorsion

• Wind • Aerodynamics • Gravity/Inertia • Waves • Wakes • Fault situations

• (Earth quakes)



Structural modes of 3-bladed turbines during operation

1st fore-aft twr 1st side-side twr 1st BW flap 1 sym. flap

1st FW flap 1st BW edge 1st FW edge 1st drivetrain

Courtesy M. H. Hansen, DTU Wind Energy, 2015



How low frequent turbulence causes high frequent exitation

Effect of rotational sampling for a 3B turbine

The turbulence level affects all frequencies and is the single most important environmental parameter regarding wind turbine loads!



Natural variation of atmospheric conditions

5

- Eg. variations in the wind shear



Shear effects on loads at 12m/s

6

Blade loads Tower loads

5MW ref. Turbine, class A turbulence

Natarajan, A., Dimitrov, N. K., Madsen, P. H., Berg, J., Kelly, M. C., Larsen, G. C., ... Thesbjerg, L. (2016). Demonstration of a Basis for Tall Wind Turbine Design, EUDP Project Final Report. DTU Wind Energy. (DTU Wind Energy E; No. 0108).

Shears can have a significant impact on blade loads, whereas other load components are less affected

Mflap

Medge

Mfore-aft

Mside-side



Importance of Veer

7

Høvsøre



Veer effects on loads at 12m/s

8

Blade loads Tower loads

5MW ref. Turbine, class A turbulence

Veer seem to have limited impact on the load level.

Mflap

Medge

Mfore-aft

Mside-side

Natarajan, A., Dimitrov, N. K., Madsen, P. H., Berg, J., Kelly, M. C., Larsen, G. C., ... Thesbjerg, L. (2016). Demonstration of a Basis for Tall Wind Turbine Design, EUDP Project Final Report. DTU Wind Energy. (DTU Wind Energy E; No. 0108).



What about wake effects?

9

- Wind farms loads and production - Wake modelling - Optimization of layout, turbine design and control (WT + WF) - Load maps for Operation & Maintenance



Principle of Dynamic Wake Meandering

10 6 April 2016

Velocity deficit

Meandering

Wind turbine wake

Added wake turbulence

The wake is superpositioned on the ambient turbulence



Wake modelling – important for loads and power

11

Lidar measurement of the wake and the DWM predicted wake center position

LES CFD

DWM



Results from Egmond aan Zee

This difference could to some extent be explained by the stable weather conditions above 10m/s, not accounted for

Larsen TJ, Aagaard Madsen H, Larsen GC, Hansen KS. Validation of the dynamic wake meander model for loads and power production in the Egmond aan Zee wind farm. Wind Energy. 2013;16(4):605-624. 10.1002/we.1563



Results from Lillgrund 3-7D spacing, single and multiple wake situations

Wake effects may cause significantly increased loads at high wind speeds, even though a single wind turbine here is “aerodynamic transparent”

Larsen TJ, Larsen GC, Aagaard Madsen H, Petersen SM. 2015. Wake effects above rated wind speed. An overlooked contributor to high loads in wind farms. In Scientific Proceedings. EWEA Annual Conference and Exhibition 2015 . European Wind Energy Association (EWEA). pp. 95-99.



Horns Rev 1 Offshore Wind Farm

14

Wind direction Probability

Wind Farm Layout

Assuming 100% availability for all WTs

1) Which WTs suffers the highest fatigue damage? 2) Which WT produces the most energy during a year?



Blade Root Lifetime Fatigue Damage

15


Col-10 WTs at column 10 experience the highest blade fatigue damage

Mapping Wind Farm Load and Power Production – A Case Study on Horns Rev 1 Christos Galinos, Nikolay Dimitrov, Torben J Larsen1, Anand Natarajan and Kurt S Hansen Preliminary results – To be finally presented at Torque from Wind, 2016



Tower bottom bending Fatigue Damage


WT 60+68 suffers the largest tower damage

Mapping Wind Farm Load and Power Production – A Case Study on Horns Rev 1

Christos Galinos, Nikolay Dimitrov, Torben J Larsen1, Anand Natarajan and Kurt S Hansen Preliminary results – To be finally presented at Torque from Wind, 2016



Annual Energy Production

17


WT number 8 produces the most energy, 97% compared to a stand alone (no

wake effects) WT

Mapping Wind Farm Load and Power Production – A Case Study on Horns Rev 1 Christos Galinos, Nikolay Dimitrov, Torben J Larsen1, Anand Natarajan and Kurt S Hansen Preliminary results – To be finally presented at Torque from Wind, 2016



Different concepts

wind turbine loading

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