ABB Relion REG670, Technical Manual

Page: 277 / 1298

7.6.7.5 Design
At every execution of the function the following is calculated: active power
P
, reactive
power
Q
, rotor angle
ROTORANG
, quantity
UCOSPHI
, the positive-sequence current
CURRENT
and voltage
VOLTAGE
. All other quantities, that can as well be read as
outputs, are only calculated if the Z(R, X) enters the limit of reach zone, which is a
circle in the complex (R – X) plane. When the complex impedance Z(R, X) enters the
limit-of-reach region, the algorithm:
• determines in which direction the impedance Z moves, that is, the direction the
lens is traversed
• measures the time taken to traverse the lens from one side to the other one
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.
IEC10000116-3-en.vsd
GENMODE
Calculation of
R and X parts
of the complex
positive-
sequence
impedance
Z(R, X)
UPSRE
UPSIM
UPSMAG
R
IPSRE
IPSIM
Z(R,X)
Z(R,X)
within limit of
reach?
X
NO
Return
YES
Z(R,X)
within lens
characteristic?
NO
YES
Z(R,X)
entered lens
from?
Function alert
RIGHT
LEFT
Z(R,X)
exited lens
on the left- hand
side?
NO
YES
YES (pole- slip!)
Was
traverse time
more than
50 ms?
Motor losing
step ?
Generator losing
step ?
NO
X
R
Calculation of
positive- sequence
active power P,
reactive power Q,
rotor angle
ROTORANG
and
UCOSPHI
P
Q
ROTORANG
>= 1
Number
of pole- slips
exceeded in
a zone?
ZONE 1
ZONE 2
Open
circuit
breaker
safely
TRIP
TRIPZ1
TRIPZ2
UCOSPHI
UCOSPHI
ROTORANG
SLIPFREQ
GENMODE
MOTMODE
NO
Calculation of
R and X parts
of the complex
positive-
sequence
impedance
Z(R, X)
UPSRE
UPSIM
UPSMAG
R
IPSRE
IPSIM
Z(R,X)
Z(R,X)
within limit of
reach?
X
NO
Return
YES
Z(R,X)
within lens
characteristic?
NO
YES
Z(R,X)
entered lens
from?
Function alert
RIGHT
LEFT
Z(R,X)
exited lens
on the left- hand
side?
NO
YES
YES (pole- slip!)
Was
traverse time
more than
50 ms?
Motor losing
step ?
Generator losing
step ?
NO
X
R
Calculation of
positive- sequence
active power P,
reactive power Q,
rotor angle
ROTORANG
and
UCOSPHI
P
Q
ROTORANG
>= 1
Number
of pole- slips
exceeded in
a zone?
ZONE 1
ZONE 2
Open
circuit
breaker
safely
TRIP
TRIPZ1
TRIPZ2
UCOSPHI
UCOSPHI
ROTORANG
SLIPFREQ
MOTMODE
NO
IEC10000116 V3 EN
Figure 118: OOSPPAM Simplified function block
1MRK502052-UEN B
Section 7
Impedance protection
271
Technical manual