ABB REG670 - Page 272

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Real part (R) of Z in Ohms
Imaginary part (X) of Z in Ohms
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Ztr
Ze
Zgen
SE
RE
Z(R,X)
R
Zline
Zone 2
relay
←
Z-line
120°
←
Lens is the locus
of constant rotor (power)
angle, e.g. 120°.
Lens' width determined
by the setting StartAngle
X
Position of the OOS
relay is the origin of
the R - X plane
Zone 1
limit-of-reach
→
circle depends on
the position of the
points SE and RE
X-line
determined
by the
→
setting
ReachZ1
IEC10000112-1-en.vsd
IEC10000112 V1 EN
Figure 114: Construction of the lens characteristic for a power system
IEC10000113-2-en.vsd
d
Y
G
Generato
r
13.8 k
V
13.8 k
V
Power line
220 k
V
Infinite powe
r
system
Ou
t
-
O
f
-
Step
p
rotection
OOSPPA
M
Transforme
r
13.8 / 220 k
V
System
equivalen
t
REG
Zgen(Rgen ,
X
gen
)
Ztr(Rt
r
,
X
t
r
)
Zline(Rline,
X
line
)
Zeq(Re
q
,
X
e
q
)
Reverse
Z
ForwardZ(Forward
R
, Forward
X
)
Reverse
R
= Rg Forward
R
= Rt
r
+ Rline + Req
Reverse
X
=
Xd
’
Forward
X
=
X
t
r
+
X
line +
X
eq
A
ll impedances must be referred to the generator voltage 13.8 k
V
S
E
R
E
d
Y
G
Generato
r
13.8 k
V
13.8 k
V
Power line
220 k
V
Infinite powe
r
system
Ou
t
-
O
f
-
Step
p
rotection
OOSPPA
M
Transforme
r
13.8 / 220 k
V
System
equivalen
t
REG
Zgen(Rgen ,
X
gen
)
Ztr(Rt
r
,
X
t
r
)
Zline(Rline,
X
line
)
Zeq(Re
q
,
X
e
q
)
ReverseZ(ReverseR, ReverseX)) ForwardZ(Forward
R
, Forward
X
)
Reverse
R
= Rg Forward
R
= Rt
r
+ Rline + Req
Reverse
X
=
Xd
’
Forward
X
=
X
t
r
+
X
line +
X
eq
A
ll impedances must be referred to the generator voltage 13.8 k
V
S
E
R
E
IEC10000113 V2 EN
Figure 115: Example of an actual power system
To be able to automatically construct the lens characteristic for a system shown in
Figure 115, the actual power system must be modeled as a two-machine equivalent
system, or as a single machine – infinite bus equivalent system, the following
information is necessary: Zgen(Rgen, Xgen), Ztr(Rtr, Xtr), Zline(Rline, Xline),
Zeq(Req, Xeq), and the setting StartAngle , for example 120 degrees. All impedances
must be referred to the voltage level where the out-of-step protection relay is placed;
in the case shown in Figure
115 the relay is connected to the terminals of the generator
and, therefore, the previous quantities shall be referred to the generator nominal
Section 7 1MRK502052-UEN B
Impedance protection
266
Technical manual