The second method
This method is more exact. If the break-time of the circuit breaker is known, (and specified
as the setting
tBreaker
) than it is possible to initiate a trip (break) command almost exactly
tBreaker
milliseconds before the rotor (power) angle reaches 0 degrees, where the
currents are at their minimum possible values. The breaker contacts open at almost exactly
0 degrees, as illustrated in Figure
tBreaker
= 0.060 s. The point in time when the
breaker opening process must be initiated is estimated by solving on-line the so called
“synchronizer” differential equation. Note that if
tBreaker
is left on the initial (default)
value, which is zero (0), then the alternative setting
TripAngle
decides when the trip
command is given. If specified
tBreaker
> 0, for example
tBreaker
= 0.040 second, then
automatically, the
TripAngle
is ignored and the second, more exact method applied.
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-0.4
-0.2
0
0.2
0.4
0.6
Real part (R) of Z in Ohms
→
Im
ag
ina
ry
pa
rt
(X
) o
f Z
in
O
hm
s
→
R[Ohm]
no trip
region
loci of Z(R, X)
no trip
region
rotor angle
= ±180°
X[Ohm]
RE - Receiving End (infinite bus)
←
this circle
is loci of
the rotor
angle = 90°
2
relay
SE - Sending End (generator)
no trip
region
inside
circle
outside the
circle is the trip
region for
TripAngle <= 90°
3
here rotor
angle
is -90°
here
rotor angle
is +90°
1
trip
region
←
Z - line connects
points SE & RE
IEC10000114-1-en.vsd
IEC10000114 V1 EN
Figure 46:
The imaginary offset Mho circle represents loci of the impedance Z(R, X)
for which the rotor angle is 90 degrees
Section 7
1MRK 511 365-UUS A
Impedance protection
166
Phasor measurement unit RES670 2.1 ANSI
Technical manual
Содержание Relion 670 Series RES670
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