Distance Elements Analysis - GE D30 Instruction Manual

8 THEORY OF OPERATION
Figure 8–3: DYNAMIC SHIFT OF THE MEMORY-POLARIZED DIRECTIONAL CHARACTERISTIC
Mutual zero-sequence compensation may raise concerns regarding directional integrity on reverse faults in the situation
when the relay gets 'overcompensated'. This problem does not affect the D30 because its ground distance elements use
zero-sequence and negative-sequence currents in extra directional comparators. Both the currents are from the protected
line and are not affected by any compensation as the latter applies only to the reach defining comparators: the mho, reac-
tance and blinder characteristics.
a) DESCRIPTION
This subsection shows how to analyze the operation of the distance elements in steady states using the results of short cir-
cuit studies. All quantities are secondary ohms, volts, and amperes. Ground phase A and phase AB distance elements are
analyzed.
Assume the following settings have been entered:
Phase Rotation: ABC
Right Blinder Reach: 10 Ω
Nominal Secondary Voltage: 69.28 V
Right Blinder RCA: 88°
Distance Reach: 14 Ω
Left Blinder Reach: 5 Ω
Distance RCA: 88°
Left Blinder RCA: 88°
Polarizing Current: Zero-sequence
Assume the following signals are injected to the relay:
= 64.71 V ∠0.0° (pre-fault)
V
A
= 25.43 V ∠–19.9°
V
A
= 80.22 V ∠–133.5°
V
B
= 77.33 V ∠135.7°
V
C
Based on the entered setting the relay calculates:
K0 = 3.58 ∠–15.2°
K0M= 0
Z = 14.00 Ω ∠88°
For the assumed steady-state injection the relay calculates:
= 58.83 V ∠–2.1°
V _1
A
GE Multilin
X
Self-polarized
837724A1.CDR
D30 Line Distance Relay
8.1 DISTANCE ELEMENTS
Memory-
polarized
(Reverse fault)
R
Memory-
polarized
(Forward fault)

8.1.5 DISTANCE ELEMENTS ANALYSIS

Non-Homogeneity Correction Angle: 3°
Directional RCA: 88°
Z0/Z1 Magnitude: 4.55
Overcurrent supervision: 3 A
Z0/Z1 Angle: –12°
Distance Comparator limit angle: 75°
Z0M/Z1 Magnitude: 0
Directional Comparator limit angle: 75°
= 4.47 A ∠–107.8°
I
A
= 2.92 A ∠68.9°
I
B
= 2.93 A ∠–51.1°
I
C
Z = 1 Ω ∠88°
D
Z = 9.99 Ω ∠2°
R
Z = 4.99 Ω ∠178°
L
= 64.71 V ∠0.0°
V _1M
A
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