6 Applications and Basic Programming
6.1 Paralleling of Active Filters
6.1.1 Parameter Set-up
The factory settings for the active filter are selected for
optimal operation for most applications with a minimum
of programming needed. The filter is set in overall
harmonic compensation mode with harmonic current
priority. Selection of readouts and information to be
displayed on the LCP status lines can be customised. In a
few cases, the filter must be tuned specially for the given
grid and load conditions.
The following steps are often sufficient to set up the filter
and get proper operation:
•
Program the external CTs:
-
Check that the CT location is correct in
parameter 300-26 CT Placement
.
-
Activate the Auto CT Detection in
parameter 300-29 Start Auto CT Detection
.
-
Confirm the found CT ratio, polarity, and
sequence.
•
Make sure that the filter is in auto mode (press
[Auto On] on the LCP).
All digital input/output terminals are multifunctional. All
terminals have factory default functions suitable for most
applications but if other special functions are required,
they must be programmed in parameter group
5-**Digital
I/O Mode
.
6.1.2 Paralleling of Active Filters
The VLT® Active Filter is designed for installation in
networks with other active infeed current suppliers and so
operate in conjunction with other active filters, UPS’s and
AFE drives. There is no limitation to the allowable number
of units. Four filters can be connected to the same CT
input and run in a master/slave configuration. The master
unit activates the individual slaves according to mitigation
demand in a cascade network. This keeps the switching
losses as low as possible and so improves the system
efficiency. The master unit automatically allocates a new
slave in case a unit is out due to service or has uninten-
tionally tripped.
6.1.3 CT-wiring for Parallel Filter
Connection
VLT active filter is designed to allow up to 4 units to run in
parallel for a harmonic and reactive compensation
extension to 4 times the individual filter rating. The parallel
installed filters use the same current input and so only one
external set of CTs have to be installed. In case additional
filtration is needed, additional filters have to use separate
current transformers installed up or down stream of the CT
signal and injection point of the paralleled installation.
PCC1
130BB713.10
AAF
AAF
AAF
AAF
Illustration 6.1 2 Sets of AAFs in Master/Slave
Applications and Basic Prog...
Operating Instructions
36
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MG90V302
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