Analysis of Wind Power Ancillary Services Characteristics ... - NREL

5
4
Ratio of Change
Summer
Winter
100
90
3
Positive Changes
80
n*∆P 2 / t [(% / min) 2 ]
2
1
0
-1
-2
-3
Negative Changes
70
60
50
40
30
20
-4
-5
10
Pos. + Neg. Changes
0
0 3 6 9 12 15 18 21 24
Hour of the Day
Figure 4-5. Number of occurrences weighted with the square of the slope of 1-hour regression for
the total output of 17 turbines (Group 2)
n*∆P 2 / t [(% / min) 2 ]
10
8
6
4
2
0
-2
-4
Positive Changes
1-hour regression
4-hour regression
-6
-8
Negative Changes
Pos. + Neg. Changes
-10
0 3 6 9 12 15 18 21 24
Hour of the Day
Figure 4-6. Number of occurrences weighted with the square of the slope of 1-hour regression for
the total output of 15 turbines (Group 3)
14