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Andreas

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Posts posted by Andreas

    Edit power curves in Excel

    in WAsP

    Posted

    It is possible to prepare a wind turbine power-curve file directly in WAsP Turbine Editor. However, sometimes it is easier to start from an existing WTG file and edit it in Excel.

    If you open an existing WTG file in the Turbine Editor, you can copy the entire table by clicking F11 and then paste it to Excel (Ctrl+V). Then, in Excel, you edit the numbers and copy (Ctrl+C) the numbers in the Speed, Power, and Ct columns. Finally, in the Turbine Editor, you select “Enable Edit”, single-click the top left wind speed value, and paste (Ctrl+V).

    General questions about modelling with WAsP

    in WAsP

    Posted

    Hi Filiberto,

    The terrain elevation in WAsP is specified as a digital height contour or vector map. The resolution of these maps depends to some extent on the terrain steepness (RIX). For example, in a relatively flat country like Denmark, you can use maps with 2.5-meter contour intervals, while in complex terrain, 5 to 10-meter intervals might be more appropriate. Roughness maps should contain the essential roughness transitions, e.g. from water to land and from open areas/farmland to forests/urban distracts. The maps should extend at least 15 km in all direction from your sites of interest.

    The ruggedness index (RIX) is a relatively simple indicator of flow separation. RIX is defined as the percentage fraction of the terrain with terrain slopes higher than a critical value of 0.3. If the slopes are below 0.3, the RIX value is 0. WAsP will give you the RIX value for every wind direction bin and an average value. I mainly use the wind direction averaged value. 

    A critical terrain slope of 0.3 for all hills is a conservative indicator of flow separation. I would therefore not be concerned if I see a RIX value of, say, 5% and similar dRIX values. In WAsP 12.6, there is a method to evaluate the similarity between two sites, including the combined effects of extrapolation distance and RIX. If you are interested, you can find the paper that describes the method here: https://doi.org/10.5194/wes-5-1679-2020

    Kind regards
    Andreas

    SRTM import error

    in Map Editor

    Posted

    Hi Filiberto, 
    These formats cannot be imported directly by WAsP. Some people use the Surfer software that can import DTED. Surfer can export *.grd files or the vector lines that the Mao Editor can read. The free QGIS software can import GeoTIFF, but I don't have much experience with that.

    Kind regards

    Andreas

    SRTM import error

    in Map Editor

    Posted

    Unfortunately, the SRTM server at USGS (US geodetic service) now requires a personal account with a password before download. This is currently not supported in the WAsP Map Editor. We have our map server called GWA Elevation with similar data, and we suggest you use that until we have a better solution. The GWA Elevation data does not include roughness changes, so you need to add that information somehow, either by manual editing or by combining a roughness map downloaded from the GWA Roughness database. Sorry for this inconvenience. We hope to have a fix for the SRTM server in the future.

    Resource Grid Obstacle Group

    in WAsP

    Posted

    Hi Lucas,

    Suppose the obstacle group is associated with the met station, then obstacle effects are only accounted for in the generalized wind climate. You need to move the obstacle group to the project level if everything, including the resource grid, should include obstacle effects

    Kind regards
    Andreas

    Mesoscale model results & WAsP (Maps)

    in WAsP

    Posted

    Hi Pedro,

    If you have a GWC, then you can use your WAsP cross-prediction script, irrespectively if the GWC stems from measurement or mesoscale simulations. The hard part is to generate the GWC from mesoscale simulations. Generalisation depends not only on your mesoscale map but also on your mesoscale simulation parameters. When making a wind atlas from mesoscale-simulations, we generally try many different setups of the mesoscale model and validate each against measurements before we decide on which configuration we will use for production runs. Therefore, it is not trivial to generate the GWC files, but once produced it is trivial to apply them in WAsP

    Kind regards,
    Andreas

    SRTM Import Error

    in Map Editor

    Posted

    Thanks, Gaoithe,

    There have been some problems with the SRTM download; when this happens, you can also download from the GWA Map Warehouse inside the Map Editor. I think it worked without problems

    Kind regards
    Andreas

    Wind profile calibration

    in WAsP CFD

    Posted

    Hi Karvel,
    I haven't used your method of reducing the hub height of the turbines before. That said, there is no fundamental difference between using the CFD or IBZ model, you can, therefore, apply the same method to the WAsP CFD model. You need to be sure that you are using CFD-results at both the mast and turbine positions. As long as you don't mix IBZ and CFD in the same project, you should be fine.
    kind regards
    Andreas

    Wasp and Windpro Licence

    in Installation and licencing

    Posted

    Hi Jose,

    You can indeed use WAsP alone. When you buy a WAsP licence, you get access to WAsP, WAsP Engineering and WAT - these can be downloaded from the wasp web-page. With WindPRO you buy the modules you need. The module MODEL is the interface between WAsP and Windpro, so you need to purchase both a WAsP license and MODEL to do resource calculations in WindPRO. You can buy WAsP licences from both DTU and EMD. If you give EMD a call, they can better describe the different modules of WindPRO.

    kind regards
    Andreas

    Error due to differences in densities of WT curves and Reference sites

    in WAsP

    Posted

    One option is to use WAsP 12 where you can select two different density correction policies in the WTG hierarchy member - that will automatically be adopted across all turbine sites. The default policy is to use interpolation as described in IEC standard 61400-12-1. The other option is to use Svenningsen extrapolation method (adjusted IEC extrapolation method, improved to match turbine control) described in the abstract/poster “Proposal of an Improved Power Curve Correction”, presented by Lasse Svenningsen (EMD International A/S) at the European Wind Energy Conference & Exhibition 2010 in Warsaw.

    WAsP 11 users do not have this option, but it is recommended to obtain a site-specific power curve from the manufacturer or investigate the two above references
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