Overestimation of energy production from wrg's

[jacksonlord]

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.

[Duncan]

Hi,

I haven't looked at OpenWind for a while, but I wanted to suggest a way of trying to work out what's happening. You could make (using a text editor) a WRG which had completely uniform values: same A, K, F for each sector and site. Then any differences you see from what you expect would be easier to understand.

That's assuming of course that OpenWind is using the sectorwise distributions and folding these with a power curve, and not just the all-sector AEP. But you could do the same with the AEP: same round number for each site in the grid, and see what's happening.

Does that help?

Duncan.

[jacksonlord]

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