ABB RELION 620 Series Technical Manual page 802

Section 4
Protection functions
796
GUID-9D427F91-9B97-4C4B-A2FA-A0772C149B38 V1 EN
Figure 406: Functional module diagram
Resonance current calculation
This module calculates the resonance current per phase set as per setting Tuning
harmonic Num. The resonance current for phase A is calculated with the equation.
2
I RESO A _ _ I
=
RMS A
GUID-283368A5-9696-4E39-8E99-7973D45B7230 V1 EN
I
RMS value of current in phase A (contains up to 11
RMS_A
I DC-component in phase A current
DC_A
Fundamental component in phase A current
I_A
I
th
K harmonic component in phase A current, K is defined by setting
K_A
Num
Calculated resonance current for phase A
I_RESO_A
The resonance current is calculated through the filter implementation. The DC and
fundamental components are removed by passing the total RMS current through the
th
High pass filter. The K
filter output through the K
High pass filter and all the harmonic Band stop filters are shown in
2 2 2
I I I
− − −
_ 1 _ _ _
A DC A K A
harmonic component is removed by passing the High pass
th
harmonic Band stop filter. The magnitude response of the
1MRS757644 F
(Equation 148)
th harmonic)
Tuning harmonic
Figure 407.
620 series
Technical Manual