Settings
Station A
Station B
PDIF
L3TCPDIF
L3TCPDIF
NoOfUsedCTs
3
3
T
raAOnInpCh
2
1
TraBOnInpCh
3
2
Currents from the secondary and tertiary windings of the power transformer are connected to
one line differential protection IED. Currents for each CT group are sent to the IED at station A
by the LDCM. To inform the differential algorithm that currents are coming from the LV sides
of the transformers,
TraAOnInpCh must be set to 2 and TraBOnInpCh to 3 (channel1 is reserved
for local measurement). This is to ensure that proper turn ratio and vector group correction is
done.
4.7.2
Line differential protection L4CPDIF
4.7.2.1
Setting example with a two-end power line
GUID-4C105C98-F9FE-41B3-A7E0-FC5430EC141A v2
In this example, a two-end 220 kV and 200 km power line is protected using L4CPDIF.
The protected zone is determined by CT positions. One three-phase CT group is placed at one
end of the power line, and another three-phase CT group is placed at the other end. Everything
that is placed between these two CT groups (including CBs) are included in the protected
zone.
To apply the exact (voltage-based) method of charging current compensation, the power line's
positive and zero-sequence capacitances must be known. If not known, the approximate
method can be applied instead.
shows the power system parameters in this example.
Table 4:
Power system parameters
Power line data
Value
Remark
Number of three-phase CT
groups
(each group represents an
independent source of
information about the current)
2
A two-end power line with one three-phase CT group installed at
each end.
Setting NoOfUsedCTs is used to indicate to L4CPDIF how many
current input channels (2, 3 or 4) with current samples are to be
read and processed.
Source impedance at both ends
4.84 Ω
-
Power line length
200 km
-
Rated voltage
220 kV
-
Line impedance ZL ≈ XL
58.64 Ω
-
Total zero sequence line
capacitance, C0
7.751e-9 x 200
7.751e-9 F per 1 km of line
Total positive sequence line
capacitance, C1
12.74e-9 x 200
12.74e-9 F per 1 km of line
Charging current
(measured without charging
current compensation)
92 A
Measured at rated voltage as the differential current under normal
load.
Rated current
1000 A
shows the relevant settings in this example.
Section 4
1MRK 505 382-UEN E
Analog and binary signal transfer for line differential protection
40
Communication set-up, 670/650 series
Application Guide
© Copyright 2017 ABB. All rights reserved
Summary of Contents for Relion 670 series
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