The energy calculation – using the Wind Atlas method (PARK with WAsP):

The energy calculation for the Lynetten project is interesting for two reasons:

Firstly, the main wind directions (south through west to north-west) are dominated by a very big city. This area is far from regular and even though skyscrapers do not dominate Copenhagen, the profile of the city is complex and the roughness of the area is very high.

The second interesting aspect is the presence of many very large obstacles to the wind adding complexity to the site.

Take a look at the screen dump in figure 2b again. You only see the wind turbines, but actually everything needed for energycalculation and environmental documentation of the project is there, packed away in separate layers. You can see the layers in the right column, holding the different types of informations for the different types of calculations.

The wind atlas method require 3 set of data:

1. The wind statistic for the region.
2. The terrain describtion (roughness, orography and obstacles).
3. The power curve for the WTG.

The wind statistic:

For all of Denmark it possible to use the special wind statistic Danmark92. This is based on a central wind statistic (Beldringe, from EU-Wind Atlas) which has an add-on that correct the energy level based on validation from many long term operating WTGs. In/near Copenhagen, the correction factor is 0.85.

The wind statistic is attached in the Site data object.

Terrain description:

The terrain roughness is described using the area object (there are more alternative ways to describe roughness – in later project of the month other will be demonstrated). This is shown in figure 3. While the background roughness is set to roughness class 1.5 every distinctive type of area gets its own signature and roughness. For instance the solid red signature is “City” and designated roughness class 3.2.

The legend can be seen in figure 4.

Figure 3: Roughness classification with area-object in WindPRO. The big red area is Copenhagen roughness class 3.2.

Figure 4: Legend for areas in area object, which freely can be defined.

The area information is stored in the area object and assigned to the layer “Area information”. This overlay can thereby easily be switched on and off. From the area-object, there has to be performed an export of roughness lines, to get suitable input for WAsP calculation. The exported .map file must be linked from the site data object.

Topographically the area is homogenous and flat. For this reason height contours has not beincluded in the project.

 

  

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