ABB REG670 Applications Manual page 280

Section 8
Impedance protection
274
Set ZC to 0.15 and AnglePhi to 90°.
The warning angle (StartAngle) should be chosen not to cross into normal operating
area. The maximum line power is assumed to be 200 MVA. This corresponds to
apparent impedance:
2 2
U 20
= = =
Z 2 ohm
S 200
EQUATION1976 V1 EN
Simplified, the example can be shown as a triangle, see figure 142.
IEC07000016 V1 EN
Figure 142: Simplified figure to derive StartAngle
ZB
³
angleStart arctan + arctan
Zload
EQUATION1977 V2 EN
In case of minor damped oscillations at normal operation we do not want the
protection to start. Therefore we set the start angle with large margin.
Set StartAngle to 110°.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
X
ZA
Zload
ZB
ZA 0.25
=
arctan + arctan
2
Zload
1MRK 502 071-UEN -
en07000016.vsd
0.19
»
0 13 0
= 7.1 + 5.4
2
Application manual
(Equation 166)
R
(Equation 167)