Setting Guidelines; General; Setting Of Zone1; Setting Of Overreaching Zone - ABB RELION 670 Series Applications Manual

Section 7
Impedance protection
7.1.3

Setting guidelines

7.1.3.1

General

The settings for the distance protection function are done in primary values. The instrument
transformer ratio that has been set for the analog input card is used to automatically convert
the measured secondary input signals to primary values used in the distance protection
function.
The following basics should be considered, depending on application, when doing the setting
calculations:
• Errors introduced by current and voltage instrument transformers, particularly under
transient conditions.
• Inaccuracies in the line zero-sequence impedance data, and their effect on the calculated
value of the earth-return compensation factor.
• The effect of infeed between the IED and the fault location, including the influence of
different Z0/Z1 ratios of the various sources.
• The phase impedance of non transposed lines is not identical for all fault loops. The
difference between the impedances for different phase-to-earth loops can be as large as
5-10% of the total line impedance.
• The effect of a load transfer between the IEDs of the protected fault resistance is
considerable, the effect must be recognized.
• Zero-sequence mutual coupling from parallel lines.
7.1.3.2

Setting of zone1

The different errors mentioned earlier usually require a limitation of the underreaching zone
(normally zone 1) to 75 - 90% of the protected line.
In case of parallel lines, consider the influence of the mutual coupling according to section
"Parallel line application with mutual coupling"
application. We recommend to compensate setting for the cases when the parallel line is in
operation, out of service and not earthed and out of service and earthed in both ends. The
setting of earth fault reach should be selected to be <85% also when parallel line is out of
service and earthed at both ends (worst case).
7.1.3.3

Setting of overreaching zone

The first overreaching zone (normally zone2) must detect faults on the whole protected line.
Considering the different errors that might influence the measurement in the same way as for
zone1, it is necessary to increase the reach of the overreaching zone to at least 120% of the
protected line. The zone2 reach can be even higher if the fault infeed from adjacent lines at
remote end are considerable higher than the fault current at the IED location.
The setting must not exceed 80% of the following impedances:
• The impedance corresponding to the protected line, plus the first zone reach of the
shortest adjacent line.
• The impedance corresponding to the protected line, plus the impedance of the maximum
number of transformers operating in parallel on the bus at the remote end of the
protected line.
If the requirements in the bullet—listed paragraphs above gives a zone2 reach less than 120%,
the time delay of zone2 must be increased by approximately 200ms to avoid unwanted
operation in cases when the telecommunication for the short adjacent line at remote end is
180
and select the case(s) that are valid in your
1MRK 505 343-UEN B
SEMOD168241-1 v2
SEMOD168247-4 v2
SEMOD168247-15 v2
SEMOD168247-19 v3
Application manual