400kV. The outer boundary
RLdOutFw obtains in this particular case its value according to
.
min
0.9 137.2 123.5
L
L
RLdOutFw K
R
=
×
=
×
=
W
EQUATION1343 V1 EN-US
(Equation 432)
It is a general recommendation to set the inner boundary
RLdInFw of the oscillation detection
characteristic to 80% or less of its outer boundary. Exceptions are always possible, but must
be considered with special care especially when it comes to settings of timers
tP1 and tP2
included in oscillation detection logic. This requires the maximum permitted setting values of
factor
kLdRFw = 0.8. Equation
presents the corresponding maximum possible value of
RLdInFw.
98.8
=
×
=
W
RLdInFw
kLdRFw RLdOutFw
EQUATION1344 V3 EN-US
(Equation 433)
The load angles, which correspond to external δ
Out
and internal δ
In
boundary of proposed
oscillation detection characteristic in forward direction, are calculated with sufficient accuracy
according to equation
respectively.
155.75
2 arc tan
2 arc tan
64.5
2
2 123.5
d
æ
ö
æ
ö
ç
÷
= ×
= ×
=
°
ç
÷
ç
÷
×
×
è
ø
è
ø
S
Out
Z
RLdOutFw
EQUATION1345 V1 EN-US
(Equation 434)
max
155.75
2 arc tan
2 arc tan
76.5
2
2 98.8
d
æ
ö
æ
ö
ç
÷
= ×
= ×
=
°
ç
÷
ç
÷
×
×
è
ø
è
ø
S
In
Z
RLdInFw
EQUATION1346 V1 EN-US
(Equation 435)
The required setting
tP1 of the initial oscillation detection timer depends on the load angle
difference according to equation
.
76.5
64.5
1
13.3
360
2.5 360
In
Out
si
tP
ms
f
d
d
-
° -
°
=
=
=
×
°
×
°
EQUATION1347 V1 EN-US
(Equation 436)
The general tendency should be to set the
tP1 time to at least 30 ms, if possible. Since it is not
possible to further increase the external load angle δ
Out
, it is necessary to reduce the inner
boundary of the oscillation detection characteristic. The minimum required value is calculated
according to the procedure listed in equation
min
1
30
tP
ms
=
EQUATION1348 V1 EN-US
(Equation 437)
min
min
360
1
360 2.5 0.030 64.5
91.5
In
si
Out
f tP
d
d
-
=
°×
×
+
=
°×
×
+
° =
°
EQUATION1349 V1 EN-US
(Equation 438)
1MRK 505 343-UEN B
Section 7
Impedance protection
369
Application manual
Summary of Contents for Relion 670 series
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