ABB RER620 Technical Manual page 262

Section 4
Protection functions
256
R1 is positive sequence line resistance in ohm/ (miles or kms) and is provided as a setting
X1 is positive sequence line reactance in ohm/ (miles or kms) and is provided as a setting
R0 is zero sequence line resistance in ohm/ (miles or kms) and is provided as a setting
X0 is zero sequence line reactance in ohm/ (miles or kms) and is provided as a setting
Line Length is the length of the line in the units of kilometers (Km) or miles and is provided
as a setting.
If R1, X1, R0, X0 are given in ohm/mile then the length of the line Line Length should be
given in the unit of miles
If R1, X1, R0, X0 are given in ohm/Km then the length of the line Line Length should be
given in the unit of Km's.
Table 268 describes what will be the voltage phasor and current phasor under different
fault types.
Table 268: Relay voltage and current phasor identification
FLTLOOP
AG Fault
BG Fault
CG Fault
ABG Fault
BCG Fault
CAG Fault
ABCG Fault
AB Fault
BC Fault
CA Fault
ABC Fault
* indicates the respective current is ground compensated
Fault location
This module calculates the distance to fault and fault resistance from the voltage phasor
and current phasor selected based on type of the fault (see Table 268).
The algorithm uses the fundamental frequency phasor voltages and currents measured at
the relay terminal before and during the fault.
The algorithm basically is an iterative technique, performs a comparison of the pre fault
load impedance and apparent impedance during the fault, to estimate the distance to fault.
Estimated values of fault resistance, pre fault load impedance and line impedance are then
modified using the correction factors. And the corrected values are used to estimate the
final FLT_DIST and FLT_R.
During the auto-re-closure sequences the fault location is done with initial fault conditions.
Current phasor
I_A*
I_B*
I_C*
(I_A - I_B)
(I_B - I_C)
(I_C - I_A)
I_A
(I_A - I_B)
(I_B - I_C)
(I_C - I_A)
I_A
1MAC309294-MB F
Voltage phasor
V_A
V_B
V_C
(V_A - V_B)
(V_B - V_C)
(V_C - V_A)
V_A
(V_A - V_B)
(V_B - V_C)
(V_C - V_A)
V_A
RER620
Technical Manual