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
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