File structure
By using the WAsP export option under Wind Resources, you can save your scaled wind‐resource results as a wind resource grid (.wrg) file. Each .wrg file line corresponds to a cell center and reports the frequency of wind occurrence by direction as well as the overall Weibull parameters—scale (A, in m/s) and shape (k, dimensionless)—obtained by fitting a Weibull distribution to the wind‐speed data at that point.
The very first line of a .wrg file specifies the grid layout and origin. For example:
62 53 451341 4549268 0Here, 62 and 53 are the number of cells in the X and Y directions, respectively. Next come the easting and northing (in meters, UTM coordinates) of the grid’s lower‑left corner. The final value is the uniform cell size in meters; it reads 0 when the mesh is irregular, and otherwise shows the grid spacing (e.g. 100) for a regular grid.
Subsequent lines each begin with the literal GridPoint and describe one cell center. A typical line looks like this:
GridPoint 451341 4549268 867 50.0 4.85 5.120 62.20 12 674 48 511 …In this line, 451341 and 4549268 are the UTM easting and northing of the point, 867 m is its elevation above sea level, and 50.0 m is the height above ground. The next two values, 4.85 and 5.120, are the overall Weibull scale (A) and shape (k) parameters fitted to the entire wind‑speed distribution at that point, ignoring wind direction. 62.20 W/m² is the power density, calculated using the empirical mean of the wind speed cubed.
Finally, the remainder of the line lists sector triplets—three integers per sector encoding (frequency × 1000, A × 10, k × 100). For example, 674 48 511 corresponds to a sector frequency of 0.674 (67.4%), a sector Weibull A of 4.8 m/s, and k of 5.11.
Grid point data
The wind resource data at each grid point is found by moving the wind rose at the climatology position to the respective grid point, using speed up factors and directional shifts as computed from the CFD simulations. Thereafter the Weibull parameters are found by fitting the Weibull distribution to the new bins within each sector of the "new" windrose. The method for transferring the measurement data to different grid locations has been previously discussed in User Meetings, and is soon to be documented in another Knowledge-based article.