Series Compensated And Adjacent Lines - ABB REL670 2.2 IEC Applications Manual

1MRK 506 369-UEN B
8.13.4.5
Line distance protection REL670 2.2 IEC
Application manual

Series compensated and adjacent lines

Setting of zone 1
A voltage reversal can cause an artificial internal fault (voltage zero) on faulty line
as well as on the adjacent lines. This artificial fault always have a resistive
component, this is however small and can mostly not be used to prevent tripping of
a healthy adjacent line.
An independent tripping zone 1 facing a bus which can be exposed to voltage
reversal have to be set with reduced reach with respect to this false fault. When the
fault can move and pass the bus, the zone 1 in this station must be blocked.
Protection further out in the net must be set with respect to this apparent fault as the
protection at the bus.
Different settings of the reach for the zone (ZMFCPDIS) characteristic in forward
and reverse direction makes it possible to optimize the settings in order to
maximize dependability and security for independent zone1.
Due to the sub-harmonic oscillation swinging caused by the series capacitor at fault
conditions the reach of the under-reaching zone 1 must be further reduced. Zone 1
can only be set with a percentage reach to the artificial fault according to the curve
in 219
p
%
100
80
60
40
20
0
20 40
IEC99000202 V1 EN-US
Figure 219: Reduced reach due to the expected sub-harmonic oscillations at
different degrees of compensation
=
c degree of compensation
EQUATION1894 V1 EN-US
60 80 100 %
99000202.vsd
æ ö
X
c
ç ÷
ç ÷
X
è ø
l
Section 8
Impedance protection
GUID-33C23BA9-5807-4E9E-859A-12D6A76304C0 v1
GUID-69E8535D-F3E2-483D-8463-089063712C67 v2
C
(Equation 381)
395