GE D90 Plus Instruction Manual page 651
Line distance protection system
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CHAPTER 15: THEORY OF OPERATION
Quadrilateral phase A to ground element analysis, before memory expires
PLUS
D90
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Table 20: Mho phase AB element conditions
Parameter
Overcurrent supervision
Mho difference angle
Reactance difference angle
Directional difference angle
The results are shown in the following table.
Table 21: Mho phase AB element analysis
Parameter
Overcurrent supervision
Mho difference angle
Reactance difference angle
Directional difference angle
The mho difference angle comparator is not satisfied. Therefore, the mho phase AB
element does not operate for this fault.
Before the memory expires, the following values are calculated for the quadrilateral phase
A to ground distance element:
The ground distance element checks for the following conditions for overcurrent
supervision and the difference angles.
Table 22: Quadrilateral phase A to ground element conditions
Parameter
Overcurrent supervision
Reactance difference angle
Zero-sequence directional
difference angle
Negative-sequence directional
difference angle
Right blinder difference angle
Left blinder difference angle
Fault type comparator
difference angle
Condition
Supervision
| (I
– I
) / √3 | >
A
B
| ∠((I
)) – ∠((V
– I
) × Z – (V
– V
A
B
A
B
| ∠((I
)) – ∠((I
– I
) × Z – (V
– V
A
B
A
B
| ∠((I
) × Z) – ∠((V
– I
– V
)_1M) | <
A
B
A
B
Calculation
| (7.39 A) / √3 | = 4.27 A
| –78.7° –30.0° | = 108.7°
| –78.7° – (–21.2°) | = 57.5°
| –21.2° – 30.0° | = 51.2°
Condition
Supervision
3 × I_0 >
| ∠(I
× Z + I_0 × K
× Z + I
A
0
G
Comparator Limit
| ∠( I_0 × Z
) – ∠(V
_1M) | <
D
A
| ∠( I
) – ∠(V
_2 × Z
_1M) | <
A
D
A
| ∠(I
× Z
+ I_0 × K
× Z
+ I
A
R
0
R
Z
) | < 90°
R
| ∠(I
× Z
+ I_0 × K
× Z
+ I
A
L
0
L
Z
) | < 90°
L
| ∠( I
) – ∠(I_0 × Z
_2 × Z
) | < 50°
A
D
D
DISTANCE ELEMENTS
Comparator Limit
– V
)_1M) | <
A
B
Comparator Limit
– I
) × Z) | <
A
B
Directional Comparator Limit
Requirement
Condition met
> 3 A
Yes
< 75°
No
< 75°
Yes
< 75°
Yes
) – ∠(j × I_0 × e
j3
× K
× Z – V
0M
A
Directional Comparator Limit
Directional Comparator Limit
) – ∠(I
× K
× Z
– V
× Z
+ I_0 × K
G
0M
R
A
A
R
) – ∠(I
× K
× Z
– V
× Z
+ I_0 × K
G
0M
L
A
A
L
Eq. 76
) | <
×
0
×
0
641
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