ABB Relion RES670, Technical Manual

Page: 166 / 934

Rotor (power) angle δ can be thought of as the angle between the two lines, connecting
point 0 in Figure
42 , that is, Z(R, X) under normal load, with the points SE and RE,
respectively. These two lines are not shown in Figure 42 . Normal values of the power
angle, that is, under stable, steady-state, load conditions, are from 30 to 60 electrical
degrees. It can be observed in Figure
43 that the angle reaches 180 degrees when the
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. Figure
43 shows the
rotor (power) angle and the magnitude of Z(R, X) against time for the case from Figure
42 .
0 200 400 600 800 1000 1200 1400
-4
-3
-2
-1
0
1
2
3
4
Time in millis econds
®
Im
pe
da
nc
e
Z
in
O
hm
a
nd
r
ot
or
a
ng
le
in
r
ad
ia
n
®
|Z| in Ohms
angle in rad
normal
load
fault 500 ms
Z(R,X) cros s e d
the im pe da nce line , Z-line ,
conne cting points S E - RE
fault
occurrs
Z(R, X) under fault lies
on the impedance line
or near (for 3-ph faults )
Unde r 3-pha s e fa ult
condition rotor a ngle
of a pp. ±180 de gre e s
is m e a s ure d ...
rotor (power)
angle
|Z|
IEC10000110-2-en.vsd
1
2
3
1
0
IEC10000110 V2 EN-US
Figure 43: 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.
Section 7
1MRK 511 408-UUS A
Impedance protection
160 Phasor measurement unit RES670 2.2 ANSI
Technical manual