jacksonlord

Thanks, I'm interested. How do I get the utility?

Are you still in need of testers?

I'm getting the error "Could not open one hierarchy member" frequently when I try to reopen WAsP projects. The reason is given that it "Failed to recover a file from the archive". This is often problematic since opening a saved project is the only way to recover a calculated wrg in case I want to do some energy captures or recalculate it to finer resolutions, rather than starting over.

Brilliant. I am traveling now but will let you know what I find...

I have been running WAsP resource grids for some time now, and I often find that the calculated energy production (and capacity factor) is being overestimated when using these wrg's in openWind, my optimization software. Sorry for the very general question, but why is this? I have been trying to bring down these numbers and have checked a few possible issues with input variables, like surface roughness and air densities, but I consistently find that the grids are overestimating production in multiple locations and scenarios by about 4 capacity factor percentage-points.

I was given RSF files along with the corresponding WRG files too, actually. Does this make it easier to transfer into something useful? OpenWind is usually able to open WRG's and then it can do energy capture calculations with them, and also export them to grids for mean speed, power densities, etc. But for some reason these WRG's I have are giving me some coordinate error when I try to import to OpenWind. I'm posting a question about this to Nick on his forum. So it's too bad that WAsP cannot open these files, or even convert them. I can write a script, perhaps. It looks like there was once a utility to convert rsf to grid, which I found on the WAsP utilities page, but I was unable to run the program because I didn't have a password.

Then how about a way to simply convert a wrg or rsf to a raster file like a surfer grid? Right now I have some wrg's and rsf's from our partners and I have no way of opening them or even converting them using WAsP....

Yes, saving a fully-calculated wrg then re-opening it later, with all the calculations and settings intact.

Can it be done?

Thanks for the tip. It is a particularly large grid. I was hoping to use it in openWind. I decreased the cell size and ran it successfully. Then I successively decreased the cell size by half and re-ran the model until the resolution was satisfactory.

Is there any way to show the diurnal distribution of data (or by month, for that matter) in the Climate Analyst?

I'm trying to run the calculation on a very large resource grid (950,000 nodes) using a pretty detailed contour vector map. When I click calculate, it says that it cannot do the calculation, and that the system reported that: "Overflow". What is this error?

WAsP Team, I have some dates and times that are missing in my data file and are not given "nulls" or placeholder values. They are simply missing so that the entire row for each missing time step will be skipped. Looks like the climate analyst takes whatever the last time step's value was and extends it until the next time. Is there a way to remove missing time steps entirely or make them null? thanks, Jackson

Duncan- thanks for the response. I see now the logic of this method. I was beginning to realize that this weekend as I examined the atlas again and put two-and-two together. My key misunderstanding, I think, was the nature of the effects on sheer from surface roughness, rather than as a retardation of the wind flow on the entire vertical profile. Also, I see now that the roughness rose has to be placed both as a child to the met tower and the turbine sites (for a homogeneous site, that is). Only placing a rose under the met tower, for example, would imply that the flow at the turbine site is less inhibited, thus more productive given the same wind resource. That also explains the AEP numbers I reported, as you said. I'm now getting the rose and change line derived values to converge as well. Thanks for the tips, jackson

The height of my met station is 58 m, and the turbines are at 80 m hub height. I figured there would be some generic sheer exponent applied? There is a single roughness change line which encircles the entire project area and assigns Zo=0.3 both inside and out. It is about 10-20 km from the site.

Duncan, Thanks for clarifying. I understand your answer and it's what I suspected--that the resulting values are those that would be sufficient to "overcome" the roughness/vegetation to result in the observed wind climate. I'm still unclear as to how it is meant to interact with the rest of the items in the project, however. It seems that by adding roughness to the observed data and increasing the atlas values, this in turn increases the wind farm production results--the logic being that the wind is stronger at this location thereby producing more power. To my humble opinion, this seems counter-intuitive and perhaps contradictory. When you measure wind at a mast, you are finding the wind speeds empirically. To say that they WOULD be higher if not for the given landscape is moot: the given landscape exists and is inextricable. It should be "baked-in" to the values both of the average wind speed and the resulting true production values. Then there is the question of assigning roughness values on the turbine sites or wind farm. Taking the model as it is, by assuming that the met mast values have a "baked-in" roughness which is homogeneous throughout the site, assigning roughness to the turbines would then be double-counting the effect of the surface on the wind. Therefore, it seems it would be best to assign the roughness to both the met station AND the turbine sites, to counteract the increased wind atlas predictions with the decreased turbine spot flow values, thereby settling the production values to their correct predictions. This is especially true in a site whose surface roughness values are spatially heterogeneous, since different spots will produce different predictions. With spatially homogeneous roughness, assigning a roughness rose to the met station and the turbine sites should cancel each other out, since one is counting up and the other down. I tried this out in WAsP and found it not necessarily to be true. With the Zo=0.3 uniform rose in the atlas, a given turbine AEP=13.2 GWh. With the (same) rose in both the atlas and the turbine, AEP=11.0 GWh. With no roses at all, AEP=10.554. So it seems that a rose on the met station will have a greater impact in magnitude that the rose at the turbine site. Which all comes back to my original question (1). With a gradient of surface roughness defined entirely in the vector map using roughness change lines, none of this should be a question to the user (although presumably the processes still go on behind the scenes), since the vector map is applied to all items in the hierarchy at once if placed properly. Unfortunately, it isn't consistent with the roses, which was my main issue raised in the first post. Sorry to be long-winded here (no pun intended)! -jackson

I have been playing with surface roughness change lines and roses in my layout and getting some very curious AEP results. There are two main issues happening, (1) the production results from roughness change lines in a terrain which is presumably run on the entire layout are substantially different than the production results from roughness roses with the same roughness value placed on each turbine of the site, and (2) roughness roses have opposite effects on wind atlases than I would expect--when the roughness value is increased in the rose child to the met station, the predicted wind speeds and power densities go up for each R-class and height. (1)- When using a roughness change line as part of the vector map which is placed as a child to the project, it has a very slight effect on the calculated expected production value of the entire site (for a particular SWT 2.3-101 turbine, a change line which effectively set the entire area with a Zo=0.3, the AEP=10.494 MWh; with the change line removed, giving the default Zo=0.03, AEP=10.554 MWh). This is a very small difference, and doesn't seem accurate to me. Vegetation with a Zo=0.3m, like a short forest, would very negatively impact the flow in a site as compared with farmland. This difference does seem to be recognized when a roughness rose is placed as child to the individual turbine, bringing the AEP=7.973 (seems like almost a little too much, actually). Why such a large discrepancy between change lines and roses? (2)- When a rose is place child to a met station, higher values of uniform surface roughness cause expected average wind speeds and power to go up in the recalculated wind atlas. This seems counter-intuitive: with taller vegetation, there would be a decrease in expected wind speeds at each height, right? Perhaps I don't fully understand the model, but not a lot is written about how exactly the roughness values effect the results in the help doc. Also, is there a way to make the roughness rose a child of a wind farm layer, rather than having to repeat loading the rose as a child for each individual turbine in a layout?

My DXF file is about 55 MB, and I’m not sure how many points and lines it has, but it was generated from a shapefile with 3922 lines then converted to a DXF_R2004 in ArcMap.

As the Map Editor is processing a large dxf of contours, it crashes unexpectedly around 25% complete, and closes without any error. I have successfully added a dxf file which is a much smaller subset of the larger contour map (clipped), and it was imported fine. So I'm assuming this is a bug which occurs on large files only? Using version 10.0.0.306

Ah ha, I never thought to just try it anyway. Thanks for your help. What do you think is the relation between the resolution of the orography data or the contour interval to the accuracy of wrg resolution? Is there some rule of thumb on grid spacing for preliminary turbine layouts and further micro-siting? I'm thinking that rolling prairie terrain with a contour interval of 3 meters could produce an accurate 20-50m grid resolution....

In making a resource grid and using the orographic flow model on a given terrain for further turbine layouts and optimizations, what is the maximum resolution of the grid that is possible in WAsP? It seems that when creating the window to produce the grid, there is no way to create one with more than 10,000 nodes. This can limit the resolution of the resulting wrg in all but the smallest projects to a grid spacing of well over 100m. Is there a way around this to get higher resolution models, and is this even desirable? It seems like resolutions of 50m and lower are common and necessary for micrositing. Thanks, Jackson