ABB PQFA, Instruction Manual

Page: 70 / 98

PQFA Instructions Manual
Asea Brown Boveri Jumet S.A.
70
10.5. Programming with PQF-Prog
10.5.1.
Filter operation principle.
The filter can have three types of effect on the network:
? ?
Filter the selected harmonics until their magnitudes are close to zero
(Maximum Filtering);
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Filter the selected harmonics until their magnitudes reach the
residual level permitted by the user (Filtering to Curve);
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Produce or absorb reactive power.
The user can put the emphasis on one of the above effects by selecting the
filtering mode. The following table shows the three available modes:
Highest priority
level Lowest priority level
Mode 1 Filtering to curve Maximum filtering Reactive
compensation
Mode 2 Filtering to curve Reactive
compensation Maximum filtering
Mode 3 Filtering to curve Reactive
compensation
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In Mode 1, the PQFA will first filter to the pre-programmed curve. Once the
requirements are fulfilled, remaining resources will be allocated to reducing
the selected harmonics as close as possible to zero. If further resources are
then available, reactive power compensation will be performed as required.
In Mode 2, the second priority after filtering to the curve is reactive power
compensation. Maximum filtering comes in third place.
In Mode 3, two levels are defined: filtering to curve and reactive power
compensation.
In any case, filtering to curve is always the first priority. The alarm contact is
activated (open) if the filtering to curve requirements are not fulfilled.
Figure 10.2 here after illustrates the principle of filtering to curve for one
particular harmonic order. The flexibility of the PQFA control is such that a
specific curve may be defined for each selected harmonic.