In Complementary Technical Content

What is a WRG file?

WRG stands for Wind Resource Grid and it was first introduced by the Risø National Laboratory (since 2008, the Technical University of Denmark, DTU). WRG files are the outputs of the Wind Atlas Analysis and Application Program (WAsP by DTU) and nowadays are also produced by Vortex and other companies.
Several tools can read and import WRG files like OpenWind, WindFarmer, and WindPro.

Example:

131 143 498153 4261720 100
GridPoint 498153 4261720 0 30 6.7 1.76 567 16 39 47 172 31 41 162 32 53 131 63 83 174 143 92 230 142 79 228 65 62 189 34 51 158 30 54 155 29 54 147 32 46 177 46 51 177 99 71 226 83 64 195 74 59 178 58 51 194
GridPoint 498253 4261720 0 30 6.7 1.75 566 16 39 46 173 31 41 163 33 53 130 64 84 177 144 91 229 141 79 227 65 62 188 34 50 158 30 54 153 29 55 148 32 46 176 46 52 178 98 71 225 82 64 194 75 59 178 57 52 195
GridPoint 498353 4261720 0 30 6.7 1.75 565 16 39 46 173 31 41 164 33 54 129 66 84 176 144 91 228 140 78 227 64 62 189 34 50 158 30 54 153 29 55 148 33 46 174 46 52 181 98 71 224 82 64 194 75 59 177 57 52 197
GridPoint 498453 4261720 0 30 6.7 1.75 564 16 40 46 173 31 41 164 33 55 130 68 84 175 145 91 227 138 78 228 64 61 190 34 50 159 30 54 153 29 55 149 33 46 174 46 52 181 97 71 223 81 64 194 75 59 178 57 52 197
GridPoint 498553 4261720 0 30 6.6 1.75 562 16 41 46 174 31 41 165 34 55 128 69 84 176 145 91 228 137 78 228 64 61 192 33 50 160 30 53 151 29 55 149 32 45 174 45 52 181 97 70 223 81 64 194 75 58 179 57 51 197
GridPoint 498653 4261720 0 30 6.6 1.75 560 16 41 46 177 31 41 163 35 54 128 69 85 178 145 91 229 137 78 226 63 61 192 34 50 160 30 53 151 29 54 148 32 46 176 45 51 179 96 70 221 81 63 194 75 58 179 57 51 196
GridPoint 498753 4261720 0 30 6.6 1.75 559 16 41 46 179 31 41 162 35 55 129 71 85 179 145 91 230 137 77 225 63 61 192 33 50 161 30 54 154 29 54 146 31 46 176 45 51 180 96 70 219 81 63 193 74 59 179 57 51 197
GridPoint 498853 4261720 0 30 6.6 1.74 560 16 41 46 179 31 41 161 36 55 131 72 86 181 145 91 229 135 77 225 63 61 192 33 50 160 30 54 155 29 53 145 31 46 175 45 51 179 96 70 218 80 63 193 75 58 179 57 51 195
GridPoint 498953 4261720 0 30 6.6 1.74 560 16 41 45 178 30 41 162 36 56 132 74 86 182 146 91 229 134 77 225 63 61 192 33 50 160 30 54 156 30 53 145 31 46 174 45 51 178 95 70 218 80 63 193 74 58 180 58 51 194
...

File structure:

The Wind Resource Grid file is an ASCII (text) file. The first line contains the coordinates, height above ground level, the number of grid points (X and Y), and the cell size. Then contains the wind rose and sector-wise wind speed distributions for each node in the grid. The detailed format of each line is shown in the table below.

Line Content
1 Nx Ny XminYmin {cell size}
Nx is the number of grid points in the X-direction
Ny is the number of grid points in the Y-direction
Xmin is the X-coordinate of the lower left corner (node) of the grid [m]
Ymin is the Y-coordinate of the lower left corner (node) of the grid [m]
{cell size} is the regular resource grid cell size [m]
2 Results for node 1
3 Results for node 2
... ...
n Results for node n

For each line, the format in columns is shown in the next table. The format is fixed, each value must be in the specified field with the fixed width.

Column WidthContents
01-10 10Text string (10 characters) identifying the site/grid point
11-20 10 X-coordinate (easting) of the site [m]
21-30 10 Y-coordinate (northing) of the site [m]
31-38 8 Z-coordinate (elevation) of the site [m]
39-43 5 Height above ground level [m a.g.l.]
44-48 5 Weibull A-parameter for the total distribution [ms-1]
49-54 6 Weibull k-parameter for the total distribution
55-69 15 Power density [Wm-2] or power production [Why-1]
70-72 3 Number of sectors
73-76 4 Frequency of occurrence for sector #1 [%·10]
77-80 4 Weibull A-parameter for sector #1 [ms-1·10]
81-85 5 Weibull k-parameter for sector #1 [·100]
86-98 13 As columns 73-85, but for sector #2 ...
... ... ...
216-228 13 As columns 73-85, but for sector #12 ...

References:

Mortensen, N. G., Heathfield, D. N., Rathmann, O., & Nielsen, M. (2011). Wind Atlas Analysis and Application Program: WAsP 10 Help Facility. Roskilde: DTU Wind Energy.

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