ABB REG650 Technical Manual page 159

1MRK 502 043-UUS B
Technical Manual
Rotor (power) angle δ can be thought of as the angle between the two lines, connecting
point 0 in Figure 68, that is, Z(R, X) under normal load, with the points SE and RE,
respectively. These two lines are not shown in
angle, that is, under stable, steady-state, load conditions are from 30 to 60 electrical
degrees. It can be observed in
complex impedance Z(R, X) crosses the impedance line SE – RE. It then changes the
sign, and continues from -180 degrees to 0 degrees, and so on.
rotor (power) angle and the magnitude of Z(R, X) against time for the case from
68.
4
3
normal
load
Z(R, X) under fault lies
2
on the impedance line
or near (for 3-ph faults)
1
0
fault 500 ms
fault
-1
occurrs
Under 3-phase fault
condition rotor angle
-2
of app. ±180 degrees
is measured ...
-3
-4
0 200 400
IEC10000110 V1 EN
Figure 69: Rotor (power) angle and magnitude of the complex impedance Z(R, X)
against the time
In order to be able to fully understand the principles of OOSPPAM (78), a stable case,
that is, a case where the disturbance does not make a generator to go out-of-step, must
be shown.
Figure
Figure 69 that the angle reaches 180 degrees when the
|Z| in Ohms
rotor (power)
angle in rad
angle
|Z|
Z(R,X) crossed
the impedance line, Z-line,
connecting points SE - RE
600 800 1000
Time in milliseconds →
Section 7
Impedance protection
68. Normal values of the power
Figure 69 shows the
1200 1400
IEC10000110-1-en.vsd
Figure
153