power factor correction harmonic filters
TRANSCRIPT
7/29/2019 Power Factor Correction Harmonic Filters
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Managing Harmonics –
A case studyJim Bridgeman
PFC Engineering
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Basics of harmonic resonance
Effects of harmonic resonance
Typical solutions applied to resonant Power Systems
Harmonic magnification case study
Introduction
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The Basics of Harmonic Resonance
kVAr
kVAScc N res )(
Vn
Harmonic
current
source (In)
Magnified In
kW
Loading
System
Impedance
PFC
Capacitors
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Effects of Harmonic Resonance
Linear load = 0 kW
Linear load = 300 kW
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Effects of Harmonic Resonance
Harmonic distortion with and without capacitors connectedwith 200A of non-linear load
0
2
4
6
8
10
12
5 7 11 13Harmonic
V n ( % )
Vn No caps
Vn Caps
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Increased voltage distortion, possibly resulting in
equipment malfunction
Loss of transformer output due to increased heating
Interference with communication systems
Premature failure of motors
Premature failure of power factor correction capacitors
Effects of Harmonic Resonance
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Typical Solutions Applied to Resonant
Power Systems
Detuning reactors
Partial harmonic filtration
Full harmonic filtration
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Typical Solutions Applied to Resonant
Power Systems –
Detuning Reactors
Tuning frequency
189Hz
Vn
Harmonic
current
source (In)
kW
Loading
System
Impedance
Detuned
PFC
Capacitors
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Typical Solutions Applied to Resonant
Power Systems –
Partial Filtration
Vn
Harmonic
current
source (In)
kW
Loading
System
Impedance
Detuned
PFC
Capacitors
Tuning frequency
210Hz
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Typical Solutions Applied to Resonant
Power Systems –
Full Filtration
Vn
Harmonic
current
source (In)
kW
Loading
System
Impedance
PFC
Capacitors
as Filters
Tuning frequency
240 HzTuning frequency
335 Hz
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Comparison of Harmonic Resonance
Solutions
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Comparison of Harmonic Resonance
Solutions
0
2
4
6
8
10
12
5 7 11 13Harmonic
V n ( % )
Vn Plain Capacitors
Vn Detuned Capacitors
Vn Partial Filtration
Vn Full Filtration
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Case Study – Harmonic Magnification at
a Car Battery Factory
Large 5th harmonic magnification excited by 600 kVAr of
capacitors
Costly installation of detuning reactors appeared to be the
only solution
A more cost effective solution involving reconfiguration of
the existing plant was found
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Case Study – Initial System
Configuration (Transformer T1)
Plain capacitors
All non-linear loading
No load damping
120 MVA 11 kV Busbar
11 kV / 415 V,
1500kVA 5.22%
600 kW Battery
Chargers
6 x 100
kVAr
"Dirty" supply
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Case Study – Initial System
Configuration (Transformer T2)
Nearly all linear loading
Significant load damping
500 kW Linear Loading
120 MVA 11 kV Busbar
11 kV / 415 V,
1500kVA 5.22%
PFC on this supply unknown
"Clean" supply
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Case Study – Effects of 5th Harmonic
Voltage Magnification
0
1
2
3
4
5
6
7
8
9
10
2 3 4 5 6 7 8 9 10 11 12 13
Harmonic
V o l t a g e d i s t o r t i o n ( % )
0 steps of capacitors
6 steps of capacitors
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Case Study – Effects of 5th Harmonic
Voltage Magnification
-500
-400
-300
-200
-100
0
100
200
300
400
500
7 . 5
8 2 . 5
1 5 7 . 5
2 3 2 . 5
3 0 7 . 5
Phase Angle Degrees
V o l t a g e ( V o l t s )
V No Capacitors
V 6 steps of capacitors
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Case Study – Reasons for severity of 5th
harmonic voltage magnification
High base level of harmonics due to all non-linear load
being connected to this supply Connection of plain capacitor banks
Total lack of harmonic damping from linear loading
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Case Study – Proposed Solution to
Problem of Harmonic Magnification
250 kW Linear
Loading
120 MVA 11 kV Busbar
11 kV / 415 V,
1500kVA 5.22%
6 x 100
kVAr 300 kW Battery
Chargers
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Case Study – Improvement in Harmonic
Performance with Re-configured Load
0
1
2
3
4
5
6
2 3 4 5 6 7 8 9 10 11 12 13
Harmonic
V o l t a g e d i s t o r t i o n
( % )
0 steps of capacitors
6 steps of capacitors
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Case Study – Effects of 5th Harmonic
Voltage Magnification
-400
-300
-200
-100
0
100
200
300
400
7 . 5
8 2 . 5
1 5 7 . 5
2 3 2 . 5
3 0 7 . 5
Phase Angle Degrees
V o l t a g e ( V o l t s )
V No Capacitors
V 6 Steps of Capacitors
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Conclusions
Harmonic resonance can be caused by connection of Power Factor Correction equipment
Various methods of avoiding this scenario involving
blocking / filtration systems are available Careful examination of the problem and more appropriate
load configuration can provide more cost effective solution to
the problem
Questions?