power factor correction harmonic filters

7/29/2019 Power Factor Correction Harmonic Filters

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Managing Harmonics –

A case studyJim Bridgeman

PFC Engineering



Basics of harmonic resonance

Effects of harmonic resonance

Typical solutions applied to resonant Power Systems

Harmonic magnification case study

Introduction



The Basics of Harmonic Resonance

kVAr

kVAScc N res )(

Vn

Harmonic

current

source (In)

Magnified In

kW

Loading

System

Impedance

PFC

Capacitors



Effects of Harmonic Resonance

Linear load = 0 kW

Linear load = 300 kW




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



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




Typical Solutions Applied to Resonant

Power Systems

Detuning reactors

Partial harmonic filtration

Full harmonic filtration




Power Systems –

Detuning Reactors

Tuning frequency

189Hz

Vn

Harmonic

current

source (In)

kW

Loading

System

Impedance

Detuned

PFC

Capacitors




Power Systems –

Partial Filtration

Vn

Harmonic

current

source (In)

kW

Loading

System

Impedance

Detuned

PFC

Capacitors

Tuning frequency

210Hz




Power Systems –

Full Filtration

Vn

Harmonic

current

source (In)

kW

Loading

System

Impedance

PFC

Capacitors

as Filters

Tuning frequency

240 HzTuning frequency

335 Hz



Comparison of Harmonic Resonance

Solutions



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



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



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



Case Study – Initial System

Configuration (Transformer T2)

Nearly all linear loading

Significant load damping

500 kW Linear Loading


11 kV / 415 V,

1500kVA 5.22%

PFC on this supply unknown

"Clean" supply



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






-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



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



Case Study – Proposed Solution to

Problem of Harmonic Magnification

250 kW Linear

Loading


11 kV / 415 V,

1500kVA 5.22%

6 x 100

kVAr 300 kW Battery

Chargers



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

( % )







-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



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?

power factor correction harmonic filters

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