Setting Guidelines - ABB RELION RET670 Applications Manual

Section 8
Impedance protection
8.14.3
450
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 (78) 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 (78) 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.

Setting guidelines

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 228.
E
A
d
= const
A
A
Z
SA
~
R
ANSI99001019 V1 EN-US
Figure 228: Protected power line as part of a two-machine system
Reduce the power system with protected power line into equivalent two-machine
system with positive sequence source impedances Z
the remote end bus B. Observe a fact that these impedances can not 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:
B
Z Z
L
behind the IED and Z
SA
Transformer protection RET670 2.2 ANSI
1MRK 504 163-UUS A
SEMOD52042-5 v4
E
B
d
= f(t)
B
SB
~
99001019_ansi.vsd
behind
SB
Application manual