Power Factor - Danfoss AHF 010 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
3 3
worst-case performance deterioration characteristics with
the background distortion.
25
20
15
10
5
0
0
Illustration 3.3 AHF 005
60
50
40
30
20
10
0
0
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
Illustration 3.5 AHF 005
16
20 40 60
Load [%]
20 40 60
Load [%]
0% unbalance
1% unbalance
2% unbalance
3% unbalance
20 40 60
Load [%]
Danfoss A/S © 05/2019 All rights reserved.
®
VLT Advanced Harmonic Filter AHF 005/AHF 010
25
20
15
10
5
0
0
THvD 0%
Illustration 3.6 AHF 010
THvD 2%
THvD 5%

3.1.1 Power Factor

In no-load conditions (the frequency converter is in stand-
by), the frequency converter current is negligible, and the
80 100
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
THvD 0%
increases with the load. Because of the higher value of the
THvD 2%
THvD 5% main inductor L
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
80 100
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
Illustration 3.7 AHF 005
1
0,9
0,8
0,7
0,6
80 100
0,5
0,4
0,3
0,2
0,1
0
0
Illustration 3.8 AHF 010
0% unbalance
1% unbalance
2% unbalance
3% unbalance
20 40 60
Load [%]
®
in the VLT Advanced Harmonic Filter
0
20 40 60
Load [%]
20 40 60
Load [%]
80 100
80 100
80 100
MG80C602