Convergence Analysis; Start-Up Characteristic - GE MiCOM P40 Agile Technical Manual

Application Notes
MiCOM P40 Agile P442, P444
2.3.1

Convergence Analysis

This analysis is based on the measurements of distance and resistance of the fault. These
measurements are taken on each phase-ground and phase-phase loops (18 loops in total).
They determine the convergence of these loops within a parallelogram-shaped, start-up
characteristic.
L = line length in km or mile s
D3 = Z3/Zd x L = X3
D4 = Zd x L = X4
For multi phase fault :
= argument of
q
For single phase fault :
q
 = argument
1
for zone 1
q
 = argument
2
for zone 2, etc...
Figure 8:

Start-up characteristic

Let R and D
lim
The pair of solutions (D
• R
(n-1)< R
fault
• D
(n-1)< D
fault
where R is the resistance limit for the single and multi phase faults. This convergence
lim
requires the equations to be collinear, therefore allowing the terms in D
discriminated.
Theoretically, zone limits are Z3, Z4, +/- R3G-R4G or +/- R3Ph-R4Ph, if zones 3 and 4 are
enabled. The slope of the characteristic mimics the characteristic of the line.
To model the fault current:
• Phase-phase loops: the values (I
• Phase-ground loops: (I
The results of these algorithms are mainly used as a backup; consequently, the circuit
breaker located at the other end is assumed to be open.
2.3.2 Start-Up
Start-up is initiated when at least one of the six measuring loops converges in the
characteristic (Z
Z (positive sequence impedance)
1
of (2 Z + Z )/ 3
1
01
of (2 Z + Z )/ 3
1
02
be the limits of the starting characteristic.
lim
(n-1), R
fault fault
, and R (n)< R
lim fault
and D (n) < D
lim fault
+ k x 3I
A 0
, Z , Z , Z , Z , Z
AN BN CN AB BC
- R
lim
(n-1)) and (D (n), R
fault fault
, and R (n-1) - R
lim fault fault
and D (n-1) - D
lim fault fault
- I ), (I - I ), or (I - I
A B B C C
), (I + k x 3I ), or (I + k
0 B 0 0 C
).
CA
P44x/EN AP/Hb6
(AP) 5-23
D
D = X3
lim

d
R
lim
- D
= X 4
lim
(n)):
(n)< 10% x R
lim
(n) < 10% x D
lim
and R to be
fault fault
) are used.
A
x 3I ) are used.
0 0
R
P3037ENa