The Pqfa: Performances; Filtering - ABB PQFA Instruction Manual

3.4.

The PQFA: performances

3.4.1. Filtering

The main requirement for an active filter installed in an industrial installation is
to attenuate the harmonics produced by the non-linear loads of the
installation.
The ideal active filter should allow the user to choose freely which harmonic
components to filter and should offer an adjustable degree of filtering.
It is also worth noting that the total harmonic voltage distortion at the point of
common coupling (PCC) is often calculated up to the 40
harmonic. Furthermore, the total number of harmonics that can be filtered
determines directly the quality of the resulting current. This is illustrated in
figure 3.5., which shows the filtered waveforms obtained by filtering up to
different harmonic levels.
(a) Filtering up to the 13
(b) Filtering up to the 25
(c) Filtering up to the 50
Figure 3.5. Waveforms obtained by eliminating the harmonic
components of a rectangular periodic signal up to the (a) 13
(b) the 25
This figure highlights the need for an active filter that can operate up to
sufficiently high harmonic frequencies.
The PQFA can filter simultaneously 20 (15) independent harmonics up to the
th
50 for 50Hz (60Hz) based networks. The number of harmonics to be filtered
as well as their frequencies is completely programmable by the user.
th
harmonic.
th
harmonic.
th
harmonic.
th
harmonic and (c) the 50
Asea Brown Boveri Jumet S.A.
PQFA Instructions Manual
th
[1] or the 50
th
harmonic,
th
harmonic
th
[2]
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