Areva MiCOM P921, Техническое руководство

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P92x/EN FT/E11 Technical Guide
User Guide
Page 52/110 MiCOM P921-P922-P923
10.7.2 df/dt functionning
3 2
3 2
2
/
- -
- -
-
-
-
=
i i
i i
i
t t
f f
dt df
3 2 - - i i
2 1
2 1
1
/
- -
- -
-
-
-
=
i i
i i
i
t t
f f
dt df
f
i-1
1
1
/
-
-
-
-
=
i i
i i
i
t t
f f
dt df
f
i
f
i-2
i i
i i
i
t t
f f
dt df
P0399ENa
-
-
=
+
+
+
1
1
1
/
f
i+1
FIGURE 2
The rates of change of frequency are calculated every cycle based upon the frequency
values being insensitives to vector shifts, phase jumps and harmonics.
NOTE: To be insensitive to the phase shift and vector jumps, we reject
all measuements of df/dt greater than 20Hz/s .