ABB RES670 Applications Manual page 115

1MRK 511 407-UEN C
Phasor measurement unit RES670 2.2 IEC
Application manual
E
A
d
= const
A
A
Z
SA
~
R
IEC99001019 V1 EN-US
Figure 46: Protected power line as part of a two-machine system
Reduce the power system with protected power line into an equivalent two-
machine system with positive sequence source impedances Z
protective relay R and Z
impedances cannot be directly calculated from the maximum three-phase short
circuit currents for faults on the corresponding busbar. It is necessary to consider
separate contributions of different connected circuits.
The required data is as follows:
=
U 400 kV
r
EQUATION1321 V1 EN-US
=
U 380 kV
min
EQUATION1322 V1 EN-US
=
f 50 Hz
r
EQUATION1323 V1 EN-US
400
=
U kV
p
3
EQUATION1324 V1 EN-US
0.11
=
U kV
s
3
EQUATION1325 V1 EN-US
=
I 1200 A
p
EQUATION1326 V1 EN-US
=
I 1 A
s
EQUATION1327 V1 EN-US
(
= +
Z 10.71 j 75.6
L 1
EQUATION1328 V1 EN-US
(
= +
Z 1.15 j 43.5
SA 1
EQUATION1329 V1 EN-US
Table continues on next page
Z
L
behind the remote end bus B. Observe the fact that these
SB
Rated system voltage
Minimum expected system voltage under critical system
conditions
Rated system frequency
Rated primary voltage of voltage (or potential) transformers
used
Rated secondary voltage of voltage (or potential) transformers
used
Rated primary current of current transformers used
Rated secondary current of current transformers used
Positive sequence line impedance
)
W
Positive sequence source impedance behind A bus
)
W
Section 7
Impedance protection
B
Z
SB
~
99001019.vsd
behind the
SA
E
B
d
= f(t)
B
109