10-26
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
DISTANCE ELEMENTS
CHAPTER 10: THEORY OF OPERATION
10
Table 10-4: Directional quadrilateral ground distance functions
Table 10-5: Non-directional mho phase distance functions
Table 10-6: Non-directional mho ground distance functions
Table 10-7: Non-directional quadrilateral phase distance functions
Table 10-8: Non-directional quadrilateral ground distance functions
10.3.4 Fast distance algorithm
In order to improve operating speed of the phase and ground distance zone 1 and zone 2 elements under CVT transient
conditions for high SIRs up to 60, a fast distance algorithm is implemented in the relay. This algorithm uses a weighted
average digital filtering technique and runs in parallel with a regular distance algorithm, which uses a fixed digital CVT
filtering technique. The fast distance algorithm applies the same comparators as a regular distance algorithm.
Characteristic
Comparator inputs
Limit angle
Reactance
I
×
Z – V
j
×
I_0
×
e
j
Θ
or j
×
I_2
×
e
j
Θ
COMP LIMIT
Directional
I_0
×
Z
D
V_1M
DIR COMP LIMIT
Directional
I_2
×
Z
D
V_1M
DIR COMP LIMIT (removed when 3I_0 > OC SUPV and I_2 < CUTOFF)
Right Blinder
I
×
Z
R
– V
I
×
Z
R
90°
Left Blinder
I
×
Z
L
– V
I
×
Z
L
90°
Fault-type
I_0
I_2
50° (removed during open pole conditions or when 3I_0 > OC SUPV
and I_2 < CUTOFF)
Zero-sequence
I_0
×
Z
D
–V_0
90° (zones and higher only; removed for zones 2 and higher during
open pole conditions)
Characteristic
Comparator inputs
Limit angle
Offset mho
I
×
Z – V
V-I
×
Z
REV
COMP LIMIT
Fault type
NOT SLG
See the Fault Type Characteristic section
Removed during open pole conditions
Characteristic
Comparator inputs
Limit angle
Offset mho
I
×
Z – V
V-I
×
Z
REV
COMP LIMIT
Fault-type
I_0
I_2
50° (removed during open pole conditions or when 3I_0 > OC
SUPV and I_2 < CUTOFF)
Characteristic
Comparator inputs
Limit angle
Forward Reactance
I
×
Z – V
I
×
Z
COMP LIMIT
Reverse Reactance
I
×
Z
REV
– V
I
×
Z
REV
COMP LIMIT
Right Blinder
I
×
Z
R
– V
I
×
Z
R
90°
Left Blinder
I
×
Z
L
– V
I
×
Z
L
90°
Fault type
NOT SLG
See the Fault Type Characteristic section
Removed during open pole conditions
Characteristic
Comparator inputs
Limit angle
Forward Reactance
I
×
Z – V
j
×
I_0
×
e
j
Θ
or j
×
I_2
×
e
j
Θ
COMP LIMIT
Reverse Reactance
I
×
Z
REV
– V
–j
×
I_0
×
e
j
Θ
or –j
×
I_2
×
e
j
Θ
COMP LIMIT
Right Blinder
I
×
Z
R
– V
I
×
Z
R
90°
Left Blinder
I
×
Z
L
– V
I
×
Z
L
90°
Fault-type
I_0
I_2
50° (removed during open pole conditions or when 3I_0 > OC
SUPV and I_2 < CUTOFF)