2 Functions
170
7SD5 Manual
C53000-G1176-C169-1
Figure 2-62 Pickup characteristic of the power swing detection for the MHO characteristic
Figure 2-63 Impedance vector during power swing
Trajectory Continu-
ity and Monotony
The rate of change of the impedance vector is very important for the differentiation
between faults and power swing conditions. This is shown in Figure 2-63. During the
power swing the measured impedance from one sample to the next has a defined
change in R and X, referred to as dR(k) and dX(k). Important is also the fact that from
one sample to the next the difference is small: i.e. |dR(k) – dR(k+1)| < threshold.
During a fault entry there is a rapid change that will not cause the power swing function
to pick up.
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