GE P444

Application Notes
P44x/EN AP/Hb
6
MiCOM P40 Agile P442, P444
(AP) 5-
145
P0493ENa
T
X
1
X
2
b
0
b
1
i
0
i
1
sample
sample
Figure 104: Frequency calculation
Frequency tracking is calculated by: freq=1/((X
2
-X
1
+ Nb
samples
)* T
samples
)
With X
1
= b
0
/(b
0
– b
1
) et X
2
= I
0
/(I
0
– I
1
).
T
samples
is the sampling period.
Nb
samples
is the number of samples per period (between b1 and i1 (b1 being excluded))
The Line & Bus frequencies are calculated with the same principle (described here after).