brand ea site identification etc final31mei2010

Site Identification and Optimal Plant Design for

Onshore and Offshore Wind Plants

Arno J. Brand

ECN Wind Energy

2 Outline - Site identification - Site characteristics - Optimal plant design - Summary

Outline

Site identification

Site characteristics

Optimal plant design


Site identification

∗ Design drivers

∗ Wind resource assessment

∗ Topography and land/sea use




Site identification


∗ Turbulence and stratification

∗ Recovery distances



Site identification



∗ Optimal spacing

∗ Optimal hub height

∗ Experience

∗ Turbine layout


Design drivers

Site identification

Annual Energy Production Cost Of Energy Predictability and Variability

depending on

Wind resource Topography and land/sea use Grid – Proximity and capacity Access – Roads, harbours, … Environmental and permitting constraints Turbine choice and layout

Mean wind

Turbulence

Seconds … Years


Wind resource assessment

Site identification

Desk top studies

Examine maps of mean wind speed Inspect wind resource tables Analyse wind time series

Source: Risø



Site identification

Desk top studies




Site identification

Desk top studies


Onshore

0%

2%

4%

6%

8%

10%

12%

0 5 10 15 20 25 30

Wind Speed [m/s]

Frequency Offshore

0%

2%

4%

6%

8%

10%

12%

0 5 10 15 20 25 30

Wind Speed [m/s]

Frequency



Site identification

Site calibration

Long-term versus short-term Measurement site versus plant site

Source: KNMI


Topography and land/sea use

OffshoreOnshore

Conditions Complex Flat

Forested

Site identification


Turbulence and stratification


OffshoreOnshore

Conditions

StableUnstableStratification

LowHigh MediumTurbulence

Complex Flat

Forested


Recovery distances

LongShort MediumRecovery distances

OffshoreOnshore

Conditions



Complex Flat

Forested



Optimal spacing



OffshoreOnshore

Conditions

7D … 10D

6D … 7D

4D … 5D 5D … 7D

2D … 3D 4D … 5D

Optimal spacing

Most frequent wind directions

Least frequent wind directions



Complex Flat

Forested


Optimal hub height



20 + D/2D 2h + D/2 DOptimal hub height

OffshoreOnshore

Conditions

7D … 10D

6D … 7D

4D … 5D 5D … 7D

2D … 3D 4D … 5D

Optimal spacing

Most frequent wind directions

Least frequent wind directions



Complex Flat

Forested


Experience


Row effect

Array effect

Neighbour effect


0%

100%

1 2 3 4 5 6 7 8 9 10

Position in row

Production

Experience – Row effectSecond or third turbine suffers most


Turbine layout

x

x

x

x

Limit for large number of wind turbines

Actual loss depends on spacing and wind speed

0

90

180

270 Wind direction


Experience – Array effectLarge production variation when wind direction not constant


Turbine layout

x

xx

x0%

100%

0 90 180 270 360

Wind direction

Production

0

90

180

270 Wind direction


Experience – Neighbour effectLower production when wind farms closely spaced


0%

100%

0 90 180 270 360

Wind direction

Production

Right Wind Farm

Left Wind Farm

Actual loss depends on distance, layout and wind speed

Turbine layout

x

x

0

90

180

270 Wind direction

Impact on annual energy production depends on wind rose


Turbine layout


• Consider constraints• Determine primary axis• Determine secondary axis• Create/Disturb regular pattern


Turbine layout




Optimised turbine layout


Maximise AEP by using wind farm design tools

State of the Art versus Trends Wake combination models Computational Fluid Dynamics solutions

Advantages versus Disadvantages Level of detail Accuracy




WakeFarm model

Nysted wind farm




Navier Stokes solver


Summary

Site identification

Select best sites – Desk top studies and Site calibration Site characteristics

Determine recovery distances Optimal plant design

Maximise Annual Energy Production


Arno J. Brand ECN Wind Energy Wind turbine rotor and Wind farm Aerodynamics M: P.O. Box 1, NL 1755 ZG Petten, Netherlands E: [email protected] T: +31 224 56 4775 F: +31 224 56 8214 I: linkedin.com/in/arnobrand

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