ABB RELION 650 SERIES, Technical Manual

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Real part (R) of Z in Ohms →
Im
ag
ina
ry
pa
rt
(X
) o
f Z
in
O
hm
s
→
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
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G
relay
relay
fault
RE
X [Ohm]
SE
X-line
→
limit of
reach
zone 2
zone 1
Z(R,X) 20 ms
after line out
this circle forms
the right-hand side
edge of the lens
0
6
pre-fault
Z(R,X)
5
1
2
3
4
0
→
pre-fault Z(R, X)
3
→
Z(R, X) under fault
5
→
Z 20 ms after line out
6
→
pow er line reclosed
R
SE RE
lens
→
110°
Z-line
→
fault
→
IEC10000111-1-en.vsd
IEC10000111 V1 EN-US
Figure 63: A stable case where the disturbance does not make the generator
to go out-of-step
It shall be observed that for a stable case, as shown in Figure 63 , where the
disturbance does not cause the generator to lose step, the complex impedance Z(R,
X) exits the lens characteristic on the same side (point 4) it entered it (point 2), and
never re-enters the lens. In a stable case, where the protected generator remains in
synchronism, the complex impedance returns to quadrant 1, and, after the
oscillations fade, it returns to the initial normal load position (point 0), or near.
6.4.7.1 Lens characteristic
GUID-F9BD3225-C87F-4FA6-A267-2248F0A4E707 v6
A precondition in order to be able to construct a suitable lens characteristic is that
the power system in which OOSPPAM is installed, is modeled as a two-machine
equivalent system, or as a single machine – infinite bus equivalent power system.
Then the impedances from the position of OOSPPAM in the direction of the
normal load flow (that is from the measurement point to the remote system) can be
taken as forward. The lens characteristic, as shown in Figure
61 and Figure 63 , is
obtained so that two equal in size but differently offset Mho characteristics are set
to overlap. The resultant lens characteristic is the loci of complex impedance Z(R,
X) for which the rotor (power) angle is constant, for example 110 degrees or 120
degrees; if the rotor (power) angle approaches this value, then there is a high risk to
have an out of step condition. The limit-of- reach circle is constructed
automatically by the algorithm; it is about 10% wider than the the circle that has
the line SE-RE as diameter (that is the out-of-step characteristic which corresponds
to the rotor (power) angle of 90 degrees). Figure
64 illustrates construction of the
lens characteristic for a power system.
1MRK 506 382-UEN A
Section 6
Impedance protection
Line distance protection REL650 2.2 IEC 141
Technical manual