ABB Relion 670 Series RES670, Technical Manual

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0 200 400 600 800 1000 1200
-5
0
5
10
15
20
25
30
35
C
urr
en
t i
n
kA
, t
rip
c
om
m
and
to
C
B
, r
ot
or
ang
le
in
ra
d
→
Time in milliseconds
→
pos. seq. current in kA
trip command to CB
rotor angle in radian
fault
occurs
←
normal load current
←
min. current
very high currents due
to out-of-step condition
←
after 1st
pole slip
←
2nd
←
rotor angle
angle towards 0°
current decreases
fault cleared
→
current increases under
fault conditions
→ ←
tBreaker = 60 ms
trip command
→
issued here
IEC10000115-1-en.vsd
IEC10000115 V1 EN
Figure 47: Trip initiation when the break-time of the circuit breaker is known
7.2.7.5 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.
1MRK 511 365-UUS A
Section 7
Impedance protection
Phasor measurement unit RES670 2.1 ANSI 167
Technical manual