Design - ABB REG650 Technical Manual

Section 6
Impedance protection
6.3.6.5
140

Design

When the complex impedance Z(R, X) enters the limit-of-reach region, the
algorithm determines the direction impedance Z moves, that is, the direction the
lens is traversed and measures the time taken to traverse the lens from one side to
the other. If the traverse time is more than the limit 40 or 50 ms, a pole-slip is
declared. If the complex impedance Z(R, X) exits the lens on the same side it
entered, then it is a stable case and the protected machine is still in synchronism. If
a pole-slip has been detected, then it is determined in which zone the centre of
oscillation is located. If the number of actual pole-slips exceeds the maximum
number of allowed pole-slips in either of the zones, a trip command is issued
taking care of the circuit breaker safety.
Calculation of Calculation of
UPSRE UPSRE
R and X parts R and X parts
UPSIM UPSIM
of the complex of the complex
UPSMAG UPSMAG
positive- positive-
IPSRE IPSRE
sequence sequence
IPSIM IPSIM
impedance impedance
Z(R, X) Z(R, X)
LEFT LEFT
Motor losing Motor losing
step ? step ?
Calculation of Calculation of
positive-sequence positive-sequence
active power P, active power P,
reactive power Q, reactive power Q,
rotor angle rotor angle
ROTORANG ROTORANG
and and
UCOSPHI UCOSPHI
IEC10000116 V1 EN
Figure 76: OOSPPAM Simplified function block
R R
X X
Z(R,X) Z(R,X)
Z(R,X) Z(R,X)
NO NO
Return Return
within limit of within limit of
reach? reach?
YES YES
Z(R,X) Z(R,X)
NO NO
within lens within lens
Function alert Function alert
characteristic? characteristic?
YES YES
Z(R,X) Z(R,X)
Z(R,X) Z(R,X)
RIGHT RIGHT
exited lens exited lens
entered lens entered lens
on the left-hand on the left-hand
from? from?
side? side?
Generator losing Generator losing
step ? step ?
Was Was
traverse time traverse time
more than more than
50 ms? 50 ms?
P P
Q Q
Number Number
ZONE 2 ZONE 2
of pole-slips of pole-slips
UCOSPHI UCOSPHI
exceeded in exceeded in
a zone? a zone?
ROTORANG ROTORANG
1MRK 502 034-UEN -
NO NO
YES YES
NO NO
YES (pole-slip!) YES (pole-slip!)
>= 1 >= 1
NO NO
Open Open
circuit circuit
ZONE 1 ZONE 1
breaker breaker
safely safely
IEC10000116-1-en.vsd
Technical Manual
R R
X X
P P
Q Q
UCOSPHI UCOSPHI
ROTORANG ROTORANG
SLIPFREQ SLIPFREQ
GEBMODE GEBMODE
MOTMODE MOTMODE
TRIP TRIP
TRIPZ1 TRIPZ1
TRIPZ2 TRIPZ2