ABB RES670 Technical Manual page 367

1MRK 511 408-UUS A
A
B
C
IEC13000178 V3 EN-US
Figure 125: Example of filter calculation
Phasor measurement unit RES670 2.2 ANSI
Technical manual
The data shown in the Figure comes from the comtrade file captured by the IED. The
following traces are presented in this Figure.
a) Waveforms of the stator three-phase currents given in primary kA.
b) RMS value of the sub-synchronous resonance current extracted by the filter in
primary amperes.
c) Frequency of the extracted sub-synchronous resonance current provided by the filter
in Hz.
Note the very narrow scale on the y-axle for b) and c). Such small scale as well
indicates with which precision and consistency the filter calculates the phasor
magnitude and frequency of the extracted stator sub-synchronous current component.
The following can be observed in the Figure:
• The stator total RMS current value is around 33 kA primary.
• The measured magnitude of the sub-synchronous current is around 173 A primary
(that is, 0.5% of the fundamental 50 Hz component).
• The frequency of this sub-synchronous current component is 31.24 Hz.
System protection and control
IEC13000178-2-en.vsd
Section 12
361