Harmonics & Solutions (Brunei 2010) - · PDF file2 © ABB Group April 12, 2010 | Sli de 3...

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© ABB Group April 12, 2010 | Slide 1

Harmonic distortions & solutionsABB S‘pore, DM, Motor & Drives, PC Wong ([email protected])


Harmonic Distortions

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180

360

540

720

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What are harmonics? Definition� Harmonics are the integer multiples of the fundamental frequency of any

periodical waveform are called e.g.

� Acoustic waves

� Electrical ‘waves’

� For power networks, 50 Hz (60 Hz) is the fundamental frequency and 150 Hz (180 Hz), 250 Hz (300 Hz) etc. are higher order harmonics viz. 3rd & 5th

� => Odd Harmonics (5th, 7th…..)

� => Even Harmonics (2nd , 4th ….)

� => Triplen Harmonics (3rd, 9th , 15th ..)

� Non-integer multiples of the fundamental frequency of any periodicalwaveform are called Inter-harmonics e.g. 2.5th => 125 Hz at 50 Hz base


Harmonics representations

0%

5%

10%

15%

20%

25%

5 7 11 13 17 19 23 25

Time domain

Frequency domain

Distorted waveform

(Fourier Analysis)

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Total Harmonic Distortion = THD

1

2

2

I

ITHD h

h�∞

==

%29100

44,43,59,57,71,93,14 220 2222222

====

++++++++++++++++++++++++++++====

THD

THD

Example: The THD for the 25 lowest harmonic components of a rectangular current is:

The basic formula of THD, Current :

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Definitions

� Point of common coupling (PCC) - is the point where the harmonic distortion is specified, e.g.- between the plant and the utility network (see PCC1) - between the non-linear load and other loads within an industrial

plant (see PCC 2).

� In-plant point of coupling (IPC)- The point inside the customer

system or installation to be studied.

Other Loads Other Loads

Converter

PCC 1

PCC 2

SubstationTransformer

Converter InputTransformer

Utility Network

MV Bus IPC

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Where do the harmonics come from?

Non-linear loads such as:

� Variable speed drives

�Uninterruptible power supplies (UPS)

� Industrial rectifiers

�Welding machines

� Fluorescent lighting systems (electronic ballast)

�Computers

� Printers

� Servers

� Electronic appliances

�……..


The Effects of Harmonic Distortions

Harmonic Currents mainly effect the power distribution system up to the rectifier:

� Additional losses in wires and cables� Extra heating of transformers� Circuit breaker malfunctioning� Triplen harmonics increase the neutral current & voltage

Harmonic Voltage can affect other equipments connected to the electrical system:

� Erratic operation of telecommunication systems, computers, videomonitors, electronic test equipments..etc.

� Resonance with power factor correction capacitors� Motor derations

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Motor Derating with supply harmonics

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12

Harmonic Voltage Distortion (%)

Der

atin

gFa

ctor




� Excessive harmonic currentmay lead to overheating (or even burning) of network components

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� Capacitor problems

Due to its lower impedance, capacitors are even more susceptible to higher order harmonics. If not protected from harmonic stress, a capacitor may fail pretty soon


Standards and Regulations for harmonics

� Purpose: To ensure that the network distortion does not exceed permissible levels for proper operation of connectedequipments

� Typical levels and tendencies :

=> THDV ≤≤≤≤ 5% and limit on each harmonic component

=> Derive current limits to obtain voltage limits

=> Take into account high order harmonics(e.g. G5/4: up to H50)

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International Standards & Regulations

� IEC 61000-2-4, Rev. 2002 (worldwide)EN 61000-2-4 (Europe)VDE 0839 Teil 2-4 (Germany)

� IEEE 519-1992 (US)

� National standardsG5/3 & G5/4 (United Kingdom)GB/T 14549-93 (China) etc.

� Utility standardse.g. Electricité de France

� Chinese standard GB/T 14549-93

� Transmission Code (S’pore)

� Project-specific requirements


How to minimize Harmonic Distortion?

�Use PWM AC Drive

�Choose a drive with effective choke filtering

�Know your total system and calculate the Harmonics

�Use 12-pulse Rectifier if feasible

�Install the Cabling and Earthingproperly

�Install Shunt Filters or Harmonic Traps if required

�Install external Active Filters

Inverter

Motor

SIZE

RECTIFIER TYPE

INDUCTOR SIZE

SIZE

FAULT LEVEL

AND IMPEDANCE

AND LOAD

INVERTER TYPE

AC DRIVE

TRANSFORMER

SUPPLY

LOAD

MVA

MVA%

DIOD

mH

PWM

kW%

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� Structural modification

� Improved internal filtering (chokes)

� 12 or more pulse drive

� Controlled active rectifier

� Strengthen supply etc

� External Passive Filter

� Capacitor + series reactor

� External Active Filter

� Active harmonic filter Technology

Reducing Harmonics


DC Link Inductor in the Filtering Section reduces Harmonic Distortion

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��

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Line Current with DC Link Inductor

Am

plitu

de (V

olts

), (A

mps

)

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-0.80

-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

Voltage Current w/o inductor Current withinductor

Line Current with DC Link Inductor is much more Sinusoidal than without Inductor


THD current vs AC or DC reactance

Line current THD vs normalized smoothingreactance

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10Normalized smoothing reactance x %

dcac

The range used in ABB drives

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Harmonics in Line Current24-pulse Rectifier

Current Waveforms

6-pulse Diode Rectifier

3 ~3

12-pulse Rectifier

3 ~ 3~

Reducing HarmonicsRectifier Selection

Z

Z


12-pulse Rectifier 30 degrees phase shift between the Supply Transformer Outputs

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Typical 12 pulse drive & transformer

Scope of supply:Scope of supply:--

Phase shifting transformer KTMP12HC800Phase shifting transformer KTMP12HC800Converter ACS 800Converter ACS 800--0707--04900490--33

Typical Rating 400 kW at 400 VTypical Rating 400 kW at 400 V


IGBT “Active” Rectifier

� Line converter and motor inverter with IGBT-power modules

� LCL-filter in line side removes high order components

� Power factor is unity (-1 in generator side) or can be controlled to be capacitive

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Low harmonics content in line current

I F U t( )

t

9 9.9 4 99 .95 9 9.9 6 99 .97 9 9.9 8 99 .99

2

1

1

2

I A C S 6 11 t( )

t

9 9.9 4 99 .95 9 9 .96 99 .97 9 9.9 8 99 .99

2

2

(

(

Line currentConventional 6 pulse Rectifier

vs.Active Rectifier

Current

IGBT “Active” Rectifier

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11

Harmonic overtones

Iνννν /I1 (%)

Line Current harmonics

6 Pulse Conventional Rectifier

ISU “Active” Rectifier

Time


Active Rectifier Drives� Wall-mounted low harmonic drive ACS800-31

5.5 - 110 kW

�Cabinet-built low harmonic drive ACS800-3745 - 2800 kW

� Harmonics mitigation built in the drive

�Drive equipped with an active supply unit

�In-built LCL line filter

�Low line harmonic content - Total current distortion less than 5.0%

�Power factor 1.0 at any load conditions

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THD Current content of AC Drives

100

60

40

15

8

5

0 20 40 60 80 100 120

PWM, No Inductor

PWM, SmallInductor

PWM, LargeInductor

12-Pulse

24-Pulse

Active Rectifier

PER CENT


Strengthen the Supply, Load 16A, Transformers 16-100kVA

Harmonic Distortion with 16A Load and 16 kVA Transformer

0

0.05

0.1

0.15

0.2

0.25

0.3

6-Pulse NoInductor

6-PulseSmall

Inductor

6-PulseLarge

Inductor

12-PulseLarge

Inductor

THD-LV

Highest-LV

THD-HV

Highest-HV

Limit 5%


00.020.040.060.080.1

0.120.140.160.18

6-Pulse NoInductor

6-PulseSmall

Inductor

6-PulseLarge

Inductor

12-PulseLarge

Inductor

THD-LV

Highest-LV

THD-HV

Highest-HV

Limit 5%


00.010.020.030.040.050.060.070.080.09

6-Pulse NoInductor

6-PulseSmall

Inductor

6-PulseLarge

Inductor

12-PulseLarge

Inductor

THD-LV

Highest-LV

THD-HV

Highest-HV

Limit 5%


0

0.01

0.02

0.03

0.04

0.05

0.06

6-Pulse NoInductor

6-PulseSmall

Inductor

6-PulseLarge

Inductor

12-PulseLarge

Inductor

THD-LV

Highest-LV

THD-HV

Highest-HV

Limit 5%

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Proper Cabling and Earthing

according to the Manufacturers Instructions reduces Harmonics

AC converter

Customer distribution board

Earthed protectiveelectrode

Concentricprotectiveconductorof the supplycable

Concentricprotectiveconductorof the supplycable

Motor3-phase


� Detuned - Single tuning frequency

� Above Tuned Frequency harmonics absorbed

� Below Tuned Frequency harmonics may be amplified

� Harmonic reduction limited by KVAr and network

Is

IhIfIh

IfIs

Tuned single arm “Passive” Filter

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� Capacitive below tuned frequency/Inductive above

� Better harmonic absorption

� Design with consideration to amplification of harmonics

� Limited by KVAr and network

Is

IhIf1Ih

If(1-3)Is

If2If3

Tuned multiple arm “Passive” Filter


Active harmonic filter

PQF

Supply LoadFundamental only

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1.3

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1.3

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idistortion

icompensation

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How does an active filter work (1) ?

PWMINVERTER

(IGBT-based)

DC ENERGYSTORAGE

PWM REACTORS

OUTPUT FILTER

LINE REACTOR

+-


Active Harmonic FilterFunctions

� Smart harmonic control & monitoring –target individual harmonics, auto-filtering / programmable, multiple filtering, high filtering efficiency, safety, communication,

� Non over-loadable

� Very fast response to load change

� Self adjustment to network change

� Standard off the shelf – no need detailed harmonic study, selectable from catalogue, easy & flexible installation, easy & quick commissioning

� Smaller, lighter, lower losses and less noise

� Free options – load balancing, flicker reduction, PF improvement

Cautions

� Advisable to operate in air-con room

� High investment in MV system –transformer coupling

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Transformer current

Filter stopped

-1000

-750

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-250

0

250

500

750

1000

0.06 0.08 0.1 0.12 0.14 0.16 0.18

[A]

Time [s]

AHF Current Site Measurement, for a Fan load


� Many options exist to attenuate harmonics

� They have advantages and disadvantages, and all show cost implications

� The best solution will depend on the total loading, the supply to site, and the standing distortions.

� The possibilities are:-

Summary

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1. Improve filtering on the drive

� Limited attenuation

� Add AC or DC chokes

� Most AC Drives has chokes as standard

2. Use passive filtering

� Tuned LC filter

� Requires reactive power to compensate

� Diode rectifier provides very limited reactive power

� Limits harmonic absorption

� Must not be allowed to run to leading power factor

� Filter can be overloaded

Summary


3. Use multi-pulse rectifier

� Passive solution

� Requires transformer,

� More economical when used with step down to avoid oversizing of LV system and losses of 2 transformers.

� Minimum size limitations

4. Use electronic solution

� Integrated in inverter with active rectifier

� Integrated into LV system

� AHF can be retrofitted to existing LV systems

Summary

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6 PulseNo chokes100 % load

With chokes100 % load

Fund 5th 7th 11th 13th 17th 19th


100 % 63 % 54 % 10 % 6.1 % 6.7 % 4.8 %

100 % 30 % 12 % 8.9 % 5.6 % 4.4 % 4.1 %

Manufacturing cost 100%


Summary


12 PulsePolygon Transformer100 % load

Double wound Transformer100 % load



100 % 11 % 5.8 % 6.2 % 4.7 % 1.7 % 1.4 %

100 % 3.6 % 2.6 % 7.5 % 5.2 % 1.2 % 1.3 %



Summary

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24 Pulse


100 % 4.0 % 2.7 % 1.0 % 0.7 % 1.4 % 1.4 %


Active Rectifier


100 % 2.6 % 3.4 % 3.0 % 0.1 % 2.1 % 2.2 %


Summary


Filter Solutions

Single arm tunedNot normally used for new installations

Multi arm tunedMost suited to DC drives

ActiveMost suited to multiple small drives

CostsIncrease

Summary

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Comparison of solutions

Example 1

6 x 30 kW Drives - 5 Duty 1 Standby

6 x 6 Pulse drives plus 1 x AHF 100 %6 x Active Rectifier AC Drive 125 %

Example 2


4 x 6 Pulse drives plus 1 x AHF 100 %4 x 12 Pulse drives 75 %4 x Active Rectifier AC Drive 82 %


Comparison of solutions

Example 3


3 x 6 Pulse drives plus 1 x AHF 100 %3 x 12 Pulse drives 95 %3 x Active Rectifier AC Drive 96 %

Example 2


3 x 6 Pulse drives plus 1 x AHF 100 %3 x 12 Pulse drives plus 1 x AHF 95 %3 x Active Rectifier AC Drive 97 %

Harmonics & Solutions (Brunei 2010) - · PDF file2 © ABB Group April 12, 2010 | Sli de 3...

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Transcript of Harmonics & Solutions (Brunei 2010) - · PDF file2 © ABB Group April 12, 2010 | Sli de 3...