Calculating Settings For Five Zone Distance Protection, Quadrilateral And Mho Characteristic Zqmpdis (21) - ABB REL650 Applications Manual

Section 3
REL650 setting examples
3.1.3
44
needed in the Two-ended over-head transmission line in a solidly grounded network
application.
For line protection, set the parameters for the Global base values for settings functions
according to instrument transformer primary rated values (recommended):
1. Set IBase to 1 000 A
2. Set VBase to 143 kV
3. Set SBase to 247.7 MVA(SBase=√3·VBase·IBase)
The GlobalBaseSel setting in a protection and control function references
a Global base values for setting function for reference of primary values.
Calculating settings for five zone distance protection,
quadrilateral and mho characteristic ZQMPDIS (21)
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 ground-return compensation factor.
• The effect of in feed 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 ground loops can be as large
as 5-10% of the total line impedance.
The purpose of distance protection is:
• Main protection for all short circuits (phase to ground, phase to phase, double phase
to ground and three phase) on the line.
• Main protection for all short circuits on the adjacent 138 kV busbar (no busbar
protection).
• Remote back-up protection for all short circuits on the 138 kV lines out from the
adjacent busbar.
• Remote back-up protection for all short circuits in the transformer connected to the
adjacent 138 kV busbar.
1MRK 506 334-UUS A
Application manual