ABB COM600 series User's & Technical Manual page 34

COM600 series 5.1 1MRS758734
Substation Analytics Technical Manual
impedance_diagram_example.png
Figure 4.3-33 Impedance diagram example
If the impedance of an individual line section varies, an accurate conversion of the fault
loop reactance into a physical fault distance, for example into kilometres, is not possible
with only one impedance setting. Therefore, SCEFRFLO allows the modeling of the
line impedance variation in IED with three line sections and with independent impedance
settings. This improves the accuracy of the physical fault distance conversion done in
the IED, especially in cases where the line impedance non-homogeneity is severe. The
number of line sections used in the conversion procedure from ohmic fault distance into
physical fault distance are defined by using the Num of line sections setting.
If Num of line sections = 0, the conversion of the electrical fault distance into a physical
distance is not done in the IED and the FLT_DISTANCE output is not valid. Estimated
impedances are still calculated and are shown on their respective outputs. In order to
guarantee accurate impedance estimation, the user should give as good values as possible
for the longitudinal impedance settings R1 line section A, X1 line section A, R0 line
section A, X0 line section A and the Line Len section A parameter corresponding to the
total line length. Other longitudinal impedance settings are disabled (sections B and C).
If Num of line sections = 1, the longitudinal impedance settings R1 line section A, X1
line section A, R0 line section A, X0 line section A and the Line Len section A parameter
are enabled for the conversion of the electrical fault distance into a physical distance.
This option should be used only in the case of a homogeneous line, for example, when
the protected feeder consists of only one conductor type. Also this option should be used
if the user is only interested in calculated fault loop reactance XFLOOP and final fault
location is done in higher system level utilizing, for example DMS-system.
If Num of line sections = 2, the longitudinal impedance settings R1 line section A, X1
line section A, R0 line section A, X0 line section A, R1 line section B, X1 line section
B, R0 line section B, X0 line section B and the parameters Line Len section A, Line Len
section B are enabled for the conversion of the electrical fault distance into a physical
distance. This option should be used in the case of a nonhomogenous line, for example,
when the protected feeder consists of two types of conductors.
If Num of line sections = 3, the longitudinal impedance settings R1 line section A, X1
line section A, R0 line section A, X0 line section A, R1 line section B, X1 line section
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