Wind resource assessment

Sven-Erik Gryning

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Learning objectives

After this lecture you will be able to:

•Explain the principle of wind resource assessment

•List the three main components for the wind atlas methodology

•Reflect over how different types of terrain affect the wind speed

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The classic problem

Troen & Petersen, 1989: European Wind Atlas

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Linear interpolation…

Troen & Petersen, 1989: European Wind Atlas

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Wind Atlas Analysis And Application Program (WAsP)

Analysis (upward):

Observed Wind Climate, obstacles, roughness, terrain elevation

→ Generalized Wind Climate

Application (downward):

Generalized Wind Climate, terrain elevation, roughness, obstacles

→ Predicted Wind Climate

Troen & Petersen, 1989:

European Wind Atlas

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Model for sheltering obstacles

Per cent reduction of the wind speed:

Troen & Petersen, 1989: European Wind Atlas

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Model for roughness of the terrain

Wind profile in equilibrium with upwind surface

Wind profile in transition

Wind profile in equilibrium with new surface

IBL: internal boundary layer

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Model for mountaneous terrain

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Speed-up over hills

Troen & Petersen, 1989: European Wind Atlas

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Time series observations

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Weibull distribution

0 4 8 12 16 20

Wind speed (ms-1)

0

5

10

15

Fre

quen

cy (

%)

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Wind farm Annual Energy Production (AEP)

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Summary

In this lecture you have learned:

•That the wind resource depends on surface roughness, orography and sheltering obstacles

•This information should be represented in detailed digital maps of the wind farm and neighbouring area