using more than one met station

[cigdemgazioglu]

Dear Wasp Team,

we want to use more than one met station in a project analysis. We are searching for a method to do this using WASP 9. However I can't do it.

If you will help me to find a way to insert more than one met station to workspace hierarcy.

thank you

[jfcorbett]

As far as I know, the right way to use two met stations is this: Add a second "project" hierarchy member to your workspace. Use the second met station in there. NB: The two projects will be completely independent from each other.

[cigdemgazioglu]

thank you jfcorbett but I want to use two met station in same project. I know that the other software can do it and I heard that wasp 5 can do it too. I need know how can I do it on Wasp 9.

[jfcorbett]

That is most definitely not possible in WAsP -- at least not in any WAsP version I know of, including 9. How would WAsP know what the wind atlas should be if there's two met stations in there?


I guess the question is: what do you want to do with the two met stations? What were you hoping WAsP would do exactly?

[cigdemgazioglu]

in some projects we are working in big areas in which we have more than one met station for better estimation of wind in the area.

I guess for better modeling of the project area more than one met station can be used and we should be able to enter those data to wasp.

By using different met stations data wasp should calculate the wind flow by doing interpolation.

[jfcorbett]

Interpolation, as in weighting the masts according to distance from the turbines? That's an engineering decision, and it shouldn't be left to WAsP or any other program, really.


What you can do is do all your calculations in two separate projects, one with each mast, and then post-process the results, i.e. average or weight them at each turbine location as you see fit. That's what we usually do, anyway.

[Niels Gylling Mortensen]

The basics of using several anemometers and/or masts with WAsP has been discussed in another thread (http://www.wasptechnical.dk/forum/viewtopic.php?id=255).


Interpolation, as in blending the results from several anemometers and/or masts, cannot be done with any presently available WAsP version. However, in addition to jfcorbett's post-processing way, there are a couple of other ways you can go:


"No interpolation" way: reorganise the WAsP hierarchy, so each of your met. masts (i.e. "wind atlas / met. station / observed wind climate" branch) becomes a child of a wind farm or a turbine site group. In a big wind farm, one group of turbines can then be calculated using one mast, another group of turbines using a second mast, and so on. All the turbine site groups must be children of the same overall wind farm if you want to calculate the wake effects for all turbines.


"Interpolation" way: In WAsP 10, there's a small tool, the "Lib interpolator”, which can interpolate between the generalised wind climates calculated at three masts. This is a 'mathematical' tool rather than a 'flow modelling' tool, and therefore must be used with the utmost care.

[cristi.stoian]

Dear Niels,
i have a question regarding my method. I have a tower with anemometers at 5 levels: 10/30/60/80/100m. I'm using another software, Windographer, where i can import the measurements from all this 5 sensors, and obtain the Vertical Wind Shear Profile, meaning I've got the value for Power Law Exponent. Next step is to filter all the data, for icing or other errors. Then i can make an extrapolation(simulate the wind) at a higher level, let-s say 120m. This extrapolation(simulation) is made taking into consideration only the measured values from all my 5 anemometers, without knowing the orography. Now i have a new time series, at 120m, obtained using the measured values from all the sensors. With this time series, i go into WAsP and i make the wind atlas at 120m, then i calculate the wind energy at 120m.
Beeing a WAsP forum i don't know if it's ok to bring in discussion other software's, but i'm interested to know if you ever used this method and if you have a feedback.

Also I'm mentioning I've made a test in Windographer in order to check the simulated values. On a 120m lattice tower, with sensors at 10/30/60/80/100/120m, i used the anemometers from 10/30/60/80/100m in order to obtained a simulated time series at 120m. The difference between the mean wind speed obtained and the measured value from the 120m anemometer was only 0.2%. This was made with 3 months of measurements.

Maybe it was interesting to make diferent wind energy calculation using diferent wind atlases ( from the anemometer from 10/30/60/80/100/120m), then calculate the wind energy production at 120m, and compare the results.

Thanks for the attention and I'm waiting for some feedback.

[Morten]

Dear Cristi,
WAsP is designed to take data from one level and make predictions at another one using its built-in flow model. Power-law extrapolation based on profile measurements may produce realistic results, e.g. when orography and roughness changes are insignificant. However, it is not our recommended general-purpose method. We prefer to let WAsP do the extrapolation.