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About Morten

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    Morten Nielsen
  1. Hi Erkan, Both of the attached WindPRO error messages say “project class failed to create a new project instance” which indicates a problem with the installation. I also see a button called “show bug report” and I guess that you will get detailed information when you press that. If that does not help you, I suggest that you contact WindPRO support. If I read your question correctly, you were able to calculate with WEng 4.0, but now are having problems going back to WEng 3.1. I don't know whether the two versions are supposed to co-exist under a WindPRO installation. If you were runn
  2. Hi Stefan, I remember one detail which used to trouble me with this script: the Lidar and reference masts sites must be given the exact names ‘L’ and ‘M’, so maybe check this first. Apart from this, I have no idea of what might be wrong. As Mark suggest, you better submit a WEng project file illustrating the problem to WAsP support together with possible additional inputs (if required, I cannot remember) for the script. Cheers, Morten
  3. Hi Pedro, I have no personal experience with this, but I believe that roughness values to the left and right side of each polygon or polyline in the SHP file should be stored in an a separate DBF file – with the same name and in the same folder, just using different filename extensions. You can read about this in the Map Editor help file section called ‘Map Formats> Vector maps> Shape files’. I am not sure exactly how you generate the DBF file with ArcGIS as I have never used this tool myself. With best regards, Morten Nielsen
  4. Hi Paul, You are right, the background flow is not irrotational, but I just think Eqn. 14 states that the flow field has no gradient. This is true for the two horizontal dimensions, since the background flow is the same everywhere. It is also true for the vertical direction, since its vertical component is zero. Report Risø-R-900 focussed on roughness-change perturbations. The model for effects of variable terrain elevation was revised in Risø-R-1356. Cheers, Morten References: https://backend.orbit.dtu.dk/ws/portalfiles/portal/7766601/RIS_R_900.pdf https://backend.orbit.dtu.dk/ws/p
  5. Alternative power curves could reflects different ambient conditions, like air density, and modes of turbine operation, like reduced tip-speed as a means for noise reduction. The changes are made by the wind turbine controller managing tip speed and blade pitch angle, so yes, you are right, this should both affect power curve and thrust-coefficient curve. However, we normally don’t know the exact strategy of the control system or the detailed rotor aerodynamics, so it is difficult to predict changes in the thrust just from changes in the power. Some manufactures supply sets of power- and th
  6. Hi Windfrosch, It is a standard deviation of the extreme wind estimate associated with the uncertainty of the fitted statistical model for the extreme-wind distribution. There are actually alternative models, see the post at http://www.wasptechnical.dk/forum/viewtopic.php?id=1060 When running the script you mention WEng will use the model defined by the selected extreme-wind-climate object, either annual maximum (AM), peak over threshold (POT) or spectral correction method (SC). Cheers, Morten
  7. Dear Sinisa Knezevic, 1) The extreme wind in WEng may be calculated by three alternative methods called the annual maximum (AM), peak-over-threshold (POT) and spectral correction (SC) methods. The theory differ for the three methods, but to generalize we could say that they first fit a statistical model for extreme events and then used that model to estimate the level of the extreme event with a fifty year return period. The uncertainty of the 50-year extreme wind estimate depends on the uncertainty of the fitted model. Read more in the WEng help file section 'WAsP Engineering modelling|
  8. Hi Windfrosch, WAsP does not support this directly, but as a work-around method you could try a modified power curve for the turbines you wish to exclude from the windfarm power curve. This modified power curve must have the usual Ct-coefficient curve but a close-to-zero power curve. Ideally that should be exactly zero power for all wind speeds, but then WAsP would fail to import the file, so better use tiny values instead. The easiest way to modify the turbine power curve is to - export to a WTG file, - open the WTG file in the WAsP turbine editor, - export to the old POW format - op
  9. Dear Vinh Le Thanh, I inserted the coordinate into Google Earth, and I agree that the roughness pattern at this site is quite complex with many small tiles and a large variation in surface roughness. From the pictures I also saw that fields are flooded in part of the year, and open water surfaces will reduce the roughness roughness. For WAsP applications you should, however, apply a roughness typical for the entire year as this is more relevant for the yearly energy production. It would be a big job to digitize a roughness map for this site. Instead, you could try to press ‘File| Import|
  10. Morten

    Lib Interpolator

    The Lib Interpolation applies simplified version of the method described in Nielsen, M. (1999), A method for spatial interpolation of wind climatologies. Wind Energ., 2: 151-166. doi:10.1002/(SICI)1099-1824(199907/09)2:33.0.CO;2-5 where it is referred to as LibInt LT.
  11. It depends a little on the job you need to do. Maybe you want to study a particular problem occurring for a specific wind direction or maybe you need to check turbine safety in general? For the latter you could try an IEC 61400-1 site assessment, which includes a list of wind conditions to check. You start by creating and selecting a group of turbines sites and their hub height. You also need to create an extreme wind climate by the WAsP Climate Analyst and import this in the WEng project. Then you open ‘Tools| Prepare data for WAT’ from the main menu. This tool will calculate the fifty-yea
  12. The basic wind input to the flow model of WAsP Engineering is a single wind condition. You may insert multiple winds in the project, but usually you have to select only one of these as reference for the calculations. Quite often you also need to specify a height and a site or a group of sites. Some of the ‘tools| scripts’ will iterate over all wind in your project, e.g. ‘Summary site report…’ and ‘Turbulence report…’, or even create a number of winds with different direction and report for these, e.g. ‘Wind speedup and deflection’. WEng can also operate on extreme wind climates (EWC). This i
  13. Morten

    .Wtg files

    Hi LinkeshD, You can create a WAsP WTG file by clicking on 'Tools| WAsP Turbine Editor' from the main menu inside WAsP. I usually start by preparing a performance table inside Excel with three columns (speed, Power, Ct) and then copy this table (without headers) to clipboard. Back in the turbine editor I select the 'Enable Edit' option and adjust the 'Table size' to the number of data points. Then I enter the upper left cell of the empty table and paste the performance table from the clipboard. Next step is to edit the 'description' string, rotor diameter, hub height and air density. If m
  14. A note for third-party readers: The assumption in my first reply was wrong. The real problem is that WAsP applies an automatic routine to detect whether a turbine is pitch or stall regulated. It simply consider a turbine to be pitch-regulated when the power curve has at least three points equal to the maximum. Unfortunately, this routing fails for measured power curves with a bit of noise in the power-curve data. It should not be a problem with power curves supplied by manufactures.
  15. Hi Ebazus, Normally WAsP Engineering calculates for specific wind conditions, not sectors. However, the tool called 'prepare data for WAT' produces a result table for the same number of sectors as defined in the supplied wind atlas file, which is a result from WAsP. These calculations are made with one reference wind for each sector with a wind direction equal to the center angle of each sector. The reference winds are generalized winds, i.e. for flat terrain with surface roughness z0=0.05m, and they may deflect over real terrain. Thus the flow inclination angle (or tilt) are calculated for
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