ABB RELION Series Technical Manual page 360

Section 4
Protection functions
354
GUID-DFEDB90A-4ECE-4BAA-9987-87F02BA0798A V3 EN
Figure 184: Functional module diagram
Harmonics calculation
This module feeds the measured residual current to the high-pass filter, where the
frequency range is limited to start from two times the fundamental frequency of the
network (for example, in a 50 Hz network the cutoff frequency is 100 Hz), that is,
summing the harmonic components of the network from the second harmonic. The
output of the filter, later referred to as the harmonics current, is fed to the Level
detector and Current comparison modules.
The harmonics current I_HARM_RES is available in the monitored data view. The
value is also sent over horizontal communication to the other protection relays on the
parallel feeders configured in the protection scheme.
1.0
0.5
0
0 f
GUID-F05BA8C4-AC2B-420C-AE9D-946E815682D5 V1 EN
Figure 185: High-pass filter
2f
Frequency
1MRS758755 A
REC615 and RER615
Technical Manual