Power Factor - Danfoss VLT AHF 005 Design Manual

Basic Operating Principle o...
frequency converter installations often show that the
performance of the filter is slightly better with a 2%
background distortion. However, the complexity of the grid
conditions and the mix of specific harmonics does not
provide a general rule about the performance on a
distorted grid. Illustration 3.3 and Illustration 3.4 show
worst-case performance deterioration characteristics with
the background distortion.
25
20
15
10
5
0
0 20 40
Load [%]
Illustration 3.3 AHF 005
60
50
40
30
20
10
0
0 20 40
Load [%]
Illustration 3.4 AHF 010
Performance at 10% THDv has not been plotted. However,
the filters have been tested and can operate at 10% THDv,
but the filter performance can no longer be guaranteed.
The filter performance also deteriorates with the unbalance
of the supply. Typical performance is shown in
Illustration 3.5 and Illustration 3.6.
14
12
10
8
6
4
2
0
0 20 40
Load [%]
Illustration 3.5 AHF 005
MG80C502
Design Guide
THvD 0%
THvD 2%
THvD 5%
60 80 100
THvD 0%
THvD 2%
THvD 5%
60 80 100
0% unbalance
1% unbalance
2% unbalance
3% unbalance
60 80 100
Danfoss A/S © 10/2016 All rights reserved.
25
20
15
10
5
0
0 20 40
Load [%]
Illustration 3.6 AHF 010

3.1.1 Power Factor

In no-load conditions (the frequency converter is in stand-
by), the frequency converter current is negligible, and the
main current drawn from the grid is the current through
the capacitors in the harmonic filter. Therefore, the power
factor is close to 0, capacitive. The capacitive current is
approximately 25% of the filter nominal current (depends
on filter size, typical values of 20–25%). The power factor
increases with the load. Because of the higher value of the
®
main inductor L in the VLT
0
AHF 005, the power factor is slightly higher than in the
®
VLT Advanced Harmonic Filter AHF 010.
Illustration 3.7 and Illustration 3.8 show typical values for
the true power factor on AHF 010 and AHF 005.
1
0,9
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
0 20 40
Load [%]
Illustration 3.7 AHF 005
1
0,9
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
0 20 40
Load [%]
Illustration 3.8 AHF 010
0% unbalance
1% unbalance
2% unbalance
3% unbalance
60 80 100
Advanced Harmonic Filter
60 80 100
60 80 100
15
3 3