ABB RES670 Applications Manual page 119

1MRK 511 407-UEN C
Phasor measurement unit RES670 2.2 IEC
Application manual
Multiply the required resistance for the same safety factor K
between actual voltage and 400kV when the rated voltage of the line under
consideration is higher than 400kV. The outer boundary RLdOutFw obtains in this
particular case its value according to equation 19.
= ×
RLdOutFw K R
L L
EQUATION1343 V1 EN-US
It is a general recommendation to set the inner boundary RLdInFw of the
oscillation detection characteristic to 80% or less of its outer boundary. Take
special care during the settings of timers tP1 and tP2 which is included in the
oscillation detection logic. This requires the maximum permitted setting values of
factor kLdRFw = 0.8. Equation
value of RLdInFw.
= ×
RLdInFw kLdRFw RLdOutFw
EQUATION1344 V3 EN-US
The load angles, which correspond to external δ
proposed oscillation detection characteristic in forward direction, are calculated
with sufficient accuracy according to equation
æ
d
= × ç
2 arc tan
ç
Out
×
2 RLdOutFw
è
EQUATION1345 V1 EN-US
æ
Z
d
= × ç
2 arc tan
ç
In
×
2 RLdInFw
è
EQUATION1346 V1 EN-US
The required setting tP1 of the initial oscillation detection timer depends on the
load angle difference according to equation 23.
d d
-
76.5
= =
In Out
tP 1
× °
f 360 2.5 360
si
EQUATION1347 V1 EN-US
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
necessary to reduce the inner boundary of the oscillation detection characteristic.
The minimum required value is calculated according to the procedure listed in
equation 24, 25, 26 and 27.
= × =
0.9 137.2 123.5
min
20 presents the corresponding maximum possible
= W
98.8
21
ö
Z
æ
S
÷ = ×
2 arc tan
ç
÷
è 2 123.5
ø
ö
æ
S
÷ = ×
2 arc tan
ç
÷
è
ø
max
° - °
64.5
=
13.3 ms
× °
Section 7
Impedance protection
with the ratio
L
W
and internal δ boundary of
Out In
and 22 respectively.
155.75 ö
= °
64.5
÷
×
ø
ö
155.75
= °
76.5
÷
×
2 98.8 ø
, it is
Out
(Equation 19)
(Equation 20)
(Equation 21)
(Equation 22)
(Equation 23)
113