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Measuring Wind in Forest and Wind Resource Estimate! Måns Håkansson Thomas Stalin

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Background

• Wind Power is never easy • Little experience of wind power in Forest • Genuin uncertainty

– Wind resurse – Loads – Production

• Rapid installation 200-300 MW per year from 2010

• Generate knowledge ASAP

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Three areas of work

• Wind measurements in forest

– Wind potential – Turbulens – Wind shear

• Two Testturbines at Rynningsnäs

– Nordex N90 80/100 height – Load Measurements

• Research program

– CFD, Lidar, COAMPS and Storm

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Wind Measurements

Own measurements: • Five own masts on sites 100 to 140 meter • One research mast of 210 m instr. 7 levels • >10 Telecommaster, 90/72 meter, two levels, • >10 Sodar measurements

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Measurement Grid South Sweden

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Telecommast

Positiv • Fast instrumentation • No permit • Cost efficient • Measurement of wind speed

and direction, tempreture, air pressure and humidity

• Electricity for heated instruments

• Reference serie Negativ

• Distance to site • Larger uncertainty • Disturbance from other

equipment

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Rynningsnäs

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Wind Evaluation

• Nomal one years of measurement • Three years prefered • Summer equaly low wind speed • Winter that makes difference • Difficult to make normal year correction

– No reference series – No Wind turbine production – Large differense in wind index

– Swedish index – Danish index – NCAR

– How to compare with MIUU

© Vattenfall AB 27 March 2015

12

Normal year correction - results

Standard deviation

Annual production (MWh)

Danish 5.6% 4100

NCAR (production) 6.2% 3700

Single turbine (Målajord) 6.3% 3900

Swedish 7.1% 3600

NCAR (wind) 12.5% 3800

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Sodar

• Test at Ryningsnäs together with 96 m measurement mast • From December –07 until June –08 • Wind speed, wind shear and turbulence data • Reliable 98-99%, data availability • 0,1 m/s less than mast measurements • Lidar method development, vary fragile and 4x cost.

10%

15%

20%

25%

30%

35%

0 5 10 15 20Wind speed (m/s)

Turb

ulen

ce in

tens

ity (%

)

IEC: A class

IEC: B class

Mast 97 m

Sodar 100 m

Sodar 125 m

Sodar 150 m

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Ryningsnäs load measurements

• Nordex N90 80 and 100 m hub height • Strain gauges

– Blade roots – Main shaft – Tower top – Tower bottom

• PLC signals • Measurement mast 140 m • ECN instrumentation • Evaluate together with Nordex

– Compare with design loads and measured loads on prototype

– Power curve in forest

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Computerised Fluid Dynamics

• Follow the development • Modells not accurate enough, round robin test • Indication of problem • Further time for method development

– Tree canopy model – Boundary conditions

• First test on flat forest together with Lidar measurements

• Dream to have CFD, together with wind measurement from site,

decribe the full wind field over the area.

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STORM

• MM5 • Area 150 x 150 km • 1 km2 resolution • 48 hours prognosis two

times per day • Part of normal weather

prognosis • Compare with

measurements and evaluate

• Try all possible methods

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COAMPS

• Mesoscale three dimensional none hydrostatic model • Naval Research Laboratory • Grid resolution 500 m • Area 140 x 200 km • Comparison COAMPS with measurements • MIUU seem to overestimate windspeed

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Future is Higher Towers

• Measurements show that the average yearly windspeeds in south of Sweden on 100 meter hub hight gives too low IRR

• Increase of hub hight to 140 meter gives 50% higher production

• With cost efficient towers it is possible to give better rate of return

• Steel Towers reached upper limit => – Hybrid concrete towers – Lattice or Hybrid lattice towers