Resistive Reach With Load Encroachment Characteristic - ABB RELION 670 SERIES Applications Manual

Section 8
Impedance protection
8.11.3.2
354
X1
8
Zm

Resistive reach with load encroachment characteristic

The procedure for calculating the settings for the load encroachment consist basically to
define the load angle LdAngle, the blinder RLdFwd in forward direction and blinder
RLdRev in reverse direction, as shown in figure 108.
LdAngle
LdAngle
RLdRev
ANSI05000226 V1 EN
Figure 170: Load encroachment characteristic
The load angle LdAngle is the same in forward and reverse direction, so it could be suitable
to begin to calculate the setting for that parameter. Set the parameter to the maximum
possible load angle at maximum active load. A value bigger than 20° must be used.
The blinder in forward direction, RLdFwd, can be calculated according to equation 103.
V
2
min
= ×
RLdFwd 0.8
P exp max
where:
P exp max is the maximum exporting active power
V min
is the minimum voltage for which the Pexp max occurs
0.8 is a security factor to ensure that the setting of
resistive load.
X
RLdFwd
LdAngle
LdAngle
en05000226_ansi.vsd
RLdFwd can be lesser than the calculated minimal
1MRK 506 369-UUS -
R
Line distance protection REL670 2.2 ANSI
Application manual