siemens low harmonics frequency converters

For internal use only / © Siemens AG 2010. All Rights Reserved.

Low Harmonics

Frequency Convertors

Patrick New, Siemens nv / SA

Product Manager Drive Technologies

© Siemens AG 2010. All Rights Reserved. 10/06/2010 Howest - Lemcko

Line harmonics

Definition

Electrical loads with non-linear characteristics connected to a line

power supply with sinusoidal voltage source (generator,

transformer) draws a non-sinusoidal current that distorts the

voltage at the line supply connection point - PCC (Point of

Common Coupling).

Harmonics cause a voltage drop at the transformer and

disturb other loads at the PCC


Line harmonics

Definition

According to Fourier, a non-sinusoidal

signal can be decomposed in a sum of

some of its multiple in frequency called

harmonics


Line harmonics

International standard

IEEE 519 – 1992

Sets limits for voltage and current harmonics both for the

individual consumer and for the connection point (PCC)

Used in:

Europe

USA & Canada

Many parts of Asia

Isc/ILoad Vk < 11 11< h < 17 17 < h < 23 23 < h < 35 35 < h THD

< 20 >5% 4.0 2.0 1.5 0.6 0.3 5 %

20 < 50 5%-2% 7.0 3.5 2.5 1.0 0.5 8 %

> 50 <2% 10.0 4.5 4.0 1.5 0.7 12 %

IEEE 519-1992 Maximum Harmonic Current Distortion in Percent of ILoad


Line harmonics

International standard

EN 61000-2-4

Compatibility Levels for Low-Frequency

Conducted Disturbances in Industrial Plants

EN 61000-2-4 does not define limits for harmonic currents.

Limits are specified only for harmonic voltages and the total

harmonic distortion of the voltage THD(V).


Line harmonics

6-pulse frequency converter

Line side Converter side


Line harmonics

6-pulse system

6-pulse rectifier circuits, only generate odd currents and harmonic

voltages that cannot be divided by 3:

h = n * 6 ± 1 where n = 1, 2, 3, ...

h = 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, ...


Line harmonics

Improvement of a 6-pulse system

Insertion of a line reactor to improve the waveform


Line harmonics

Relative short-circuit power on a 6-pulse system


Line harmonics

12-pulse system

The 30° phase shift in the transformer compensates

h = 5, 7, 17, 19, 29, 31, ... , so that only odd harmonic currents and

voltages that cannot be divided by 3 remain:

h = n * 12 ± 1 where n = 1, 2, 3, ...

h = 11, 13, 23, 25, 35, 37, 47, 49, ...


Line harmonics

Spectral harmonics representation of a12-pulse system

18-, 24-, 36-pulse systems reduce harmonics generation even

more


Line harmonics

Active Front End system (AFE)

Main features:

Actively-pulsed feeding / regenerative supply (4Q)

Full IGBT inverter, with a constant & controlled DC link voltage

The clean power filter ensures an almost sinusoidal power

consumption and very few system perturbations

Power factor compensation (cos φ ≈ 1)


Clean power frequency converter

Integration of an efficient Line Harmonic Filter (LHF)

LCM LHF

compact

Power

Module

+

SINAMICS G150

Clean PowerSINAMICS

G150LHF compact


Integrated line harmonics filter

Design

The converter-side harmonic absorber is tuned to the 5th

current harmonic and filters it almost entirely. The 7th, 11th and

13th harmonics are also noticeably reduced.

The line-side harmonic absorber is tuned to the non-existent 3rd

harmonic so that the line is only partially filtered.

Line ReactorSupply

Inductance

Supply

PCC

U = 2% k

LHF Converter

Number n of the Harmonic Current

1 3 5 7 11 13

Line-side Filter

Characteristics Converter-side

Filter

Characteristics

The filter is made up of a line-side and a converter-side

harmonic absorber:



Harmonics rejection

0

20

40

60

80

100

1 3 5 7 9 11 13 15 17 19 21 23 250

20

40

60

80

100

1 3 5 7 9 11 13 15 17 19 21 23 25

Converter-side

Current

Harmonics

(THD(I) = 25% - 50%)

Filter

Line-side

Current

Harmonics

(THD(I) = 5% - 7.5%)

Significant reduction of harmonics according to IEEE519


Customer benefits

Energy savings with Line Harmonics Filter

Power losses (kW) 380...480V

0

10

20

30

40

50

110 132 160 200 250 315 400 630 900 kW

G150 Clean

Pow er

Avg AFE

Energy cost - Savings (€/a)(0,08€/kWh, 8.000 h/a)

0

2.000

4.000

6.000

8.000

10.000

110 132 160 200 250 315 400 630 900 kW



Cost reduction

PCC

G130 / G150

with 6-pulse

rectifier

U = 2% k

Line

Harmonics

Filter

LHFLine

Reactor

Point of

Common

Coupling (PCC)

~~

External, Line-

side Fuse

Main

Contactor

Integration in the single cabinet = easy installation



Additional benefits

Passive components, MTBF ≈ > 75% higher than an AFE

Higher efficiency compared to active filter technologies

An additional line reactor is eliminated

Less motor stress (voltage peaks, insulation, bearing currents)


Line harmonics reduction systems

Performance overview

Complexity

Harm

onic

s

G150 Clean

Power

6-pulse

12-pulse

18-pulse



General conditions using passive filters

Used in weak supplies with uk ≥ 5%

Line harmonics are reduced, however, the level specified by IEEE519 is

not achieved

Used in extremely weak line supplies with uk ≥ 10% (e.g. ships or a UPS)

The resonance frequency of the filter can be significantly detuned, so that

the basic fundamental of the input voltage increases significantly – and

goes outside the permissible tolerance limits.

cos φ is shifted into the partial load range

Capacitive reactive power is drawn in the partial load range.

HOWEVER: Line supplies are generally pre-loaded as a result of

inductive reactive power, which LHF partially compensate

If general conditions prevent the use of an LHF, then an AFE is always a solution!



Best of breed solution selection scheme

Converter with low line harmonics

SINAMICS S150 w. AFESINAMICS G150 Clean Power

Energy recovery required Weak supply line, cos φNo

Yes

For internal use only / © Siemens AG 2010. All Rights Reserved.

Thank you for your attention!

Siemens nv / SA

Patrick New

Product Manager Drive Technologies

Square Marie Curie, 30

B-1070 Brussels

Tel: +32 2 536 69 34

Mail: [email protected]

siemens low harmonics frequency converters

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