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9.1 DISTANCE ELEMENTS
a) DEFINITIONS
The relay shapes its distance characteristics using phase angle comparators and voltage and current phasors estimated as
described in the previous section.
The following definitions pertain to all of the distance functions:
•
I
, I
, I
: phase A, B, and C current phasors.
A
B
C
•
I
: ground current from a parallel line.
G
•
V
, V
, V
: phase A to ground, phase B to ground, and phase C to ground voltage phasors.
A
B
C
•
( )_1: positive-sequence phasor of ( ) derived from the phase quantities.
•
( )_2: negative-sequence phasor of ( ) derived from the phase quantities.
•
( )_0: zero-sequence phasor of ( ) derived from the phase quantities.
•
( )M: memorized value of ( ).
•
Z: reach impedance (
•
Z
reverse reach impedance for non-directional applications (
REV:
: directional characteristic impedance (1 ∠
•
Z
D
•
Z
: right blinder characteristic impedance: Z
R
•
Z
: left blinder characteristic impedance: Z
L
•
K0: zero-sequence compensating factor: K0 = (
•
K0M: mutual zero-sequence compensating factor: K0M = 1/3 x
Θ: non-homogeneity angle setting (
•
b) DIRECTIONAL MHO CHARACTERISTIC
The dynamic 100% memory polarized mho characteristic is achieved by checking the angle between:
•
AB phase element: (I
•
BC phase element: (I
•
CA phase element: (I
•
A ground element: I
•
B ground element: I
•
C ground element: I
The limit angle of the comparator is adjustable enabling the user to shape the characteristic as a mho or a lens as shown in
the figures below.The memory-polarized mho characteristic has an excellent directional integrity built-in as explained in the
Memory polarization section.
9
9-2
∠
).
REACH
RCA
DIR RCA
=
RGT BLD
R
=
LFT BLD
L
Z0/Z1 MAG
NON-HOMOGEN ANG
) × Z – (V
– I
– V
)
and
A
B
A
B
– I
) × Z – (V
– V
)
and
B
C
B
C
– I
) × Z – (V
– V
)
and
C
A
C
A
× Z + I_0 × K0 × Z + I
× K0M × Z – V
A
G
× Z + I_0 × K0 × Z + I
× K0M × Z – V
B
G
× Z + I_0 × K0 × Z + I
× K0M × Z – V
C
G
D30 Line Distance Protection System
9.1.3 DISTANCE CHARACTERISTICS
∠
REV REACH
REV REACH RCA
).
× sin (
) × 1∠ (
RGT BLD RCA
× sin (
) × 1∠ (
LFT BLD RCA
LFT BLD RCA
∠
) – 1.
Z0/Z1 ANG
∠
Z0M/Z1 MAG
Z0M/Z1 ANG
).
(V
– V
)_1M
A
B
(V
– V
)_1M
B
C
(V
– V
)_1M
C
A
and
V
_1M
A
A
and
V
_1M
B
B
and
V
_1M
C
C
9 THEORY OF OPERATION
+ 180°).
– 90°).
RGT BLD RCA
+ 90°).
.
GE Multilin
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