ABB PQFS Installation, Operation And Maintenance Instructions page 124

Detuned bank type
5.67 %
6 %
7 %
14 %
For other types of detuned bank please contact your ABB Service provider to evaluate
the resonance frequency and the harmonics that are recommended to be deselected.
When background distortion is present on the network and detuned capacitor banks are
installed adjacent to the active filter but connected downstream of the filter CTs, filter
resources will be lost. To overcome this, it is recommended to either connect the detuned
capacitor bank upstream of the filter CTs or to use the CT connection approach shown in
Figure
124 Commissioning instructions ç Manual Power Quality Filter PQFS
either 'Y' or 'N'). The following possibilities exist to bring a harmonic out of
standby:
The user restarts a network identification process by changing the 'S'
o
indication into a 'Y' indication in the harmonic selection table
The filter automatically restarts an identification process on all
o
harmonics that were put in standby previously when a successful
identification of another harmonic is made. As a result, the harmonic
considered will be automatically filtered when the network conditions
allow for this.
· If plain capacitors (i.e. capacitor banks not incorporating detuning reactors) are
present in the network it is recommended to switch them off or change them into
detuned banks. Sometimes, the commissioning engineer is faced with an
installation where both an active filter and plain capacitors are present however.
While this is an ill advised and a technically unsound situation, ABB
acknowledges that in this case also the active filter should aim to give an optimal
performance. For this reason the control software of the filter incorporates a
Stability Detection Program (SDP) that aims to increase the filter performance in
this type of applications.
In installations where plain capacitors are present and cannot be switched off or
changed to detuned capacitor banks, adhere to the recommendations below for
optimal results.
Install the capacitor banks upstream of the active filter CT measurement
o
location
Set the filter in Mode 3
o
· In installations where detuned banks are present, it is recommended not to select
harmonic orders below the tuning frequency of the detuned banks.
indicates the harmonics recommended to be deselected for different types of
detuned banks.
Table 51: Recommended harmonics to be deselected for different detuned bank types
Harmonics recommended to be deselected
2, 3, 4
2, 3, 4
2, 3
2
85.
Table 51