GE Digital Energy L60, Инструкция по эксплуатации

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9-40 L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
FAULT LOCATOR CHAPTER 9: THEORY OF OPERATION
9
Figure 9-31: Equivalent system for fault location
The following equations hold true for this equivalent system.
Eq. 9-9
where
m = sought pu distance to fault
Z = positive sequence impedance of the line
The currents from the local and remote systems can be parted between their fault (F) and pre-fault load (pre) components:
Eq. 9-10
and neglecting shunt parameters of the line:
Eq. 9-11
Inserting the I
A
and I
B
equations into the V
A
equation and solving for the fault resistance yields:
Eq. 9-12
Assuming the fault components of the currents, I
AF
and I
BF
are in phase, and observing that the fault resistance, as
impedance, does not have any imaginary part gives:
Eq. 9-13
where Im() represents the imaginary part of a complex number. Solving this equation for the unknown m creates the
following fault location algorithm:
Eq. 9-14
where * denotes the complex conjugate and .
Depending on the fault type, appropriate voltage and current signals are selected from the phase quantities before
applying the preceding two equations (the superscripts denote phases, the subscripts denote stations).
For AG faults:
Eq. 9-15
For BG faults:
Eq. 9-16
mZ (1-m)Z
R
F
Z
A
Z
B
E
A
E
B
V
A
V
B
V
F
I
A
I
B
Local bus
Remote
bus
distance to fault
842780A1.CDR
V
A
m Z I
A
⋅ ⋅ R
F
I
A
I
B
+ ( ) ⋅ + =
I
A
I
AF
I
Apre
+ =
I
B
I
BF
I
Apre
–
=
R
F
V
A
m Z I
A
⋅ ⋅
–
I
AF
1
I
BF
I
AF
------ +
 
 
⋅
------------------------------- =
Im
V
A
m Z I
A
⋅ ⋅
–
I
AF
-------------------------------
 
 
0 =
m
Im V
A
I
AF
∗
⋅ ( )
Im Z I
A
I
AF
∗
⋅ ⋅ ( )
----------------------------------- =
I
AF
I
A
I
Apre
–
=
V
A
V
A
A
= , I
A
I
A
A
K
0
I
0A
⋅ + =
V
A
V
A
B
= , I
A
I
A
B
K
0
I
0A
⋅ + =