0.2
0.4
0.6
-0.3
0.6
-0.5
0.8
Q [pu]
0.8
1
E
D
X
s
=0
B
A
Ra
ted
M
VA
p.
f. 0
.8
lag
gin
g
Rated M
VA p.f. 0
.95 lead
ing
S
37
o
F
X
e
=0.2
C
H
18
o
Generator
Motor
Overexcited
Underexcited
F
P [pu]
en06000451.vsd
IEC06000451 V1 EN
Figure 148:
Capability curve of a generator
where:
AB
= Field current limit
BC
= Stator current limit
CD
= End region heating limit of stator, due to leakage flux
BH
= Possible active power limit due to turbine output power limitation
EF
= Steady-state limit without AVR
X
s
= Source impedance of connected power system
Loss of excitation protection can be based on directional power measurement or
impedance measurement.
The straight line EF in the P-Q plane can be transferred into the impedance plane by
using the relation shown in equation
*
2
2
2
2
*
*
*
2
2
2
2
V
V V
V
V
S
V
P
V
Q
Z
j
R
jX
I
I V
S
S S
P
Q
P
Q
×
×
×
×
=
=
=
=
=
+
= +
×
×
+
+
EQUATION1723 V1 EN
(Equation 169)
The straight line in the PQ-diagram will be equivalent with a circle in the impedance
plane, see figure
. In this example the circle is corresponding to constant Q, that is,
characteristic parallel with P-axis.
1MRK 502 071-UEN -
Section 8
Impedance protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
285
Application manual
Содержание Relion REG670
Страница 1: ...RELION 670 SERIES Generator protection REG670 Version 2 2 IEC Application manual...
Страница 2: ......
Страница 108: ...102...
Страница 132: ...126...
Страница 324: ...318...
Страница 442: ...436...
Страница 476: ...470...
Страница 628: ...622...
Страница 718: ...712...
Страница 728: ...722...
Страница 768: ...762...
Страница 778: ...772...
Страница 779: ...773...