locus in an impedance plane, see figure
. This locus can enter the operating characteristic
of a distance protection and cause, if no preventive measures have been considered, its
unwanted operation.
R
jX
Operating characteristic
Impedance locus at
power swing
IEC09000224_1_en.vsd
IEC09000224 V1 EN-US
Figure 239: Impedance plane with Power swing detection operating characteristic and
impedance locus at power swing
7.14.2.2
Basic characteristics
M13874-11 v5
Power swing detection function (ZMRPSB) detects reliably power swings with periodic time of
swinging as low as 200 ms (which means slip frequency as high as 10% of the rated frequency
on the 50 Hz basis). It detects the swings under normal system operate conditions as well as
during dead time of a single-pole automatic reclosing cycle.
ZMRPSB function is able to secure selective operation for internal faults during power. The
operation of the distance protection function remains stable for external faults during the
power swing condition, even with the swing (electrical) centre located on the protected power
line.
The operating characteristic of the ZMRPSB function is easily adjustable to the selected
impedance operating characteristics of the corresponding controlled distance protection
zones as well as to the maximum possible load conditions of the protected power lines. See
the corresponding description in
“Technical reference manual” for the IEDs.
7.14.3
Setting guidelines
SEMOD52042-5 v4
Setting guidelines are prepared in the form of a setting example for the protected power line
as part of a two-machine system presented in figure
.
99001019.vsd
~
~
E
A
d
A
= const
d
B
= f(t)
E
B
A
B
Z
SA
Z
SB
Z
L
R
IEC99001019 V1 EN-US
Figure 240: Protected power line as part of a two-machine system
1MRK 505 343-UEN B
Section 7
Impedance protection
365
Application manual
Summary of Contents for Relion 670 series
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