harmocs ABB+Harmonics+&+Solutions.pdf

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

Harmonic distortions & solutions

© ABB Group April 12, 2010 | Slide 1

Harmonic Distortions

1.50 1.00 0.50 0.00 0 720

540

360

180

-0.50 -1.00 -1.50

© ABB Group April 12, 2010 | Slide 2

1

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 periodical waveform are called Inter-harmonics e.g. 2.5th => 125 Hz at 50 Hz base

© ABB Group April 12, 2010 | Slide 3

Harmonics representations Distorted waveform (Fourier Analysis) Time domain

25% 20% 15%

Frequency domain

10% 5% 0% © ABB Group April 12, 2010 | Slide 4

5

7

11

13

17

19

23

25

2

Total Harmonic Distortion = THD The basic formula of THD, Current : ∞

THD =

h =2

Ih

2

I1

Example: The THD for the 25 lowest harmonic components of a rectangular current is: 2 2 2 2 2 2 + 14,32 + 9,1 + 7,7 + 5,9 + 5,3 + 4,4 + 42 20 THD = 100 THD = 29% © ABB Group April 12, 2010 | Slide 5

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.

Utility Network

PCC 1 Substation Transformer

MV Bus

IPC PCC 2 Converter Input Transformer

Other Loads

Other Loads Converter

© ABB Group April 12, 2010 | Slide 6

3

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 …….. © ABB Group April 12, 2010 | Slide 7

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, video monitors, electronic test equipments..etc. Resonance with power factor correction capacitors Motor derations

© ABB Group April 12, 2010 | Slide 8

4

The Effects of Harmonic Distortions Motor Derating with supply harmonics

Derating Factor

120 100 80 60 40 20 0 1

2

3

4

5

6

7

8

9

10

11

12

Harmonic Voltage Distortion (%)

© ABB Group April 12, 2010 | Slide 9

The Effects of Harmonic Distortions Excessive harmonic current may lead to overheating (or even burning) of network components

© ABB Group April 12, 2010 | Slide 10

5

The Effects of Harmonic Distortions 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

© ABB Group April 12, 2010 | Slide 11

Standards and Regulations for harmonics Purpose: To ensure that the network distortion does not

exceed permissible levels for proper operation of connected equipments

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)

© ABB Group April 12, 2010 | Slide 12

6

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 standards G5/3 & G5/4 (United Kingdom) GB/T 14549-93 (China) etc. Utility standards e.g. Electricité de France Chinese standard GB/T 14549-93 Transmission Code (S’pore) Project-specific requirements

© ABB Group April 12, 2010 | Slide 13

How to minimize Harmonic Distortion? Use PWM AC Drive SUPPLY

TRANSFORMER

FAULT LEVEL

MVA

SIZE

MVA

AND IMPEDANCE

AC DRIVE Inverter

Motor

%

RECTIFIER TYPE

DIOD

INDUCTOR SIZE

mH

INVERTER TYPE

PWM

SIZE

kW

AND LOAD

%

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 Earthing properly Install Shunt Filters or Harmonic Traps if required

LOAD

Install external Active Filters © ABB Group April 12, 2010 | Slide 14

7

Reducing Harmonics 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

© ABB Group April 12, 2010 | Slide 15

DC Link Inductor in the Filtering Section reduces Harmonic Distortion

© ABB Group April 12, 2010 | Slide 16

8

Line Current with DC Link Inductor Line Current with DC Link Inductor is much more Sinusoidal than without Inductor 1.00

Amplitude (Volts), (Amps)

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 with inductor

© ABB Group April 12, 2010 | Slide 17

THD current vs AC or DC reactance Line current THD vs normalized smoothing reactance 80 70 60 The range used in ABB drives

50 40

dc

30 20

ac 0

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

9

10

© ABB Group April 12, 2010 | Slide 18

9

Reducing Harmonics Rectifier Selection Harmonics in Line Current 6-pulse Diode Rectifier

3~

12-pulse Rectifier

3~

3

3~

24-pulse Rectifier

Z

Z

Current Waveforms

© ABB Group April 12, 2010 | Slide 19

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

© ABB Group April 12, 2010 | Slide 20

10

Typical 12 pulse drive & transformer

Scope of supply:supply:Phase shifting transformer KTMP12HC800 Converter ACS 800800-0707-04900490-3 Typical Rating 400 kW at 400 V

© ABB Group April 12, 2010 | Slide 21

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

© ABB Group April 12, 2010 | Slide 22

11

IGBT “Active” Rectifier Low harmonics content in line current Line current

Line Current harmonics

Conventional 6 pulse Rectifier vs. Active Rectifier 2

40

(

I FU ( t )

9 9. 9 4

99 . 95

9 9. 9 6

99 . 97

9 9. 9 8

99 . 99

t

15

2

10

(

9 9. 9 4

ISU “Active” Rectifier

30 20

2

I A C S 6 11 ( t )

6 Pulse Conventional Rectifier

25

1

Current

Iν /I1 (%)

35

1

99 . 95

9 9 . 96

99 . 97

9 9. 9 8

99 . 99

5 0

1

2

3

4

5

6

7

8

9

10

11

2

Time t

Harmonic overtones

© ABB Group April 12, 2010 | Slide 23

Active Rectifier Drives Wall-mounted low harmonic drive ACS800-31 5.5 - 110 kW Cabinet-built low harmonic drive ACS800-37 45 - 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

© ABB Group April 12, 2010 | Slide 24

12

THD Current content of AC Drives 5

Active Rectifier

8

24-Pulse

PER CENT

15

12-Pulse

PWM, Large Inductor

40

PWM, Small Inductor

60 100

PWM, No Inductor

0

20

40

60

80

100

120

© ABB Group April 12, 2010 | Slide 25

Strengthen the Supply, Load 16A, Transformers 16-100kVA Harmonic Distortion with 16A Load and 16 kVA Transformer 0.3 0.25

THD-LV

0.2

Highest-LV

0.15

THD-HV Highest-HV

0.1

Limit 5%

0.05 0 6-Pulse No Inductor

6-Pulse Small Inductor

6-Pulse Large Inductor

Harmonic Distortion with 16A Load and 30 kVA Transformer 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0

12-Pulse Large Inductor

Highest-LV THD-HV Highest-HV Limit 5% 6-Pulse No Inductor

Harmonic Distortion with 16A Load and 50 kVA Transformer 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0

THD-LV

6-Pulse Small Inductor

6-Pulse Large Inductor

12-Pulse Large Inductor

Harmonic Distortion with 16A Load and 100 kVA Transformer 0.06 0.05

THD-LV

Highest-LV

0.04

Highest-LV

THD-HV

0.03

THD-HV

Highest-HV

0.02

Highest-HV

Limit 5%

0.01

THD-LV

Limit 5%

0 6-Pulse No Inductor

6-Pulse Small Inductor

6-Pulse Large Inductor

12-Pulse Large Inductor

6-Pulse No Inductor

6-Pulse Small Inductor

6-Pulse Large Inductor

12-Pulse Large Inductor

© ABB Group April 12, 2010 | Slide 26

13

Proper Cabling and Earthing according to the Manufacturers Instructions reduces Harmonics

AC converter

Customer distribution board

Earthed protective electrode

Concentric protective conductor of the supply cable

Motor

Concentric protective conductor of the supply cable

3-phase

© ABB Group April 12, 2010 | Slide 27

Tuned single arm “Passive” Filter

Is If

Is

If

Ih

Ih

Detuned - Single tuning frequency Above Tuned Frequency harmonics absorbed Below Tuned Frequency harmonics may be amplified Harmonic reduction limited by KVAr and network

© ABB Group April 12, 2010 | Slide 28

14

Tuned multiple arm “Passive” Filter

If3

If2

If1

I s

I s

Ih

If(1-3) Ih

Capacitive below tuned frequency/Inductive above Better harmonic absorption Design with consideration to amplification of harmonics Limited by KVAr and network

© ABB Group April 12, 2010 | Slide 29

Active harmonic filter idistortion

Fundamental only

Supply

Load icompensation PQF

1.3

1.3

1.3

-1.3

-1.3

-1.3

© ABB Group April 12, 2010 | Slide 30

15

How does an active filter work (1) ?

LINE REACTOR OUTPUT FILTER PWM REACTORS DC ENERGY STORAGE

+ -

PWM INVERTER (IGBT-based)

© ABB Group April 12, 2010 | Slide 31

Active Harmonic Filter Functions

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 © ABB Group April 12, 2010 | Slide 32

High investment in MV system – transformer coupling

16

AHF Current Site Measurement, for a Fan load Transformer current

[A] 1000 750 500 250 0 -250 -500 -750 -1000 0.06

0.08

0.1

0.12

0.14

0.16

0.18

Time [s]

Filter stopped © ABB Group April 12, 2010 | Slide 33

Summary 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:-

© ABB Group April 12, 2010 | Slide 34

17

Summary 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 © ABB Group April 12, 2010 | Slide 35

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

© ABB Group April 12, 2010 | Slide 36

18

Summary 6 Pulse No chokes 100 % load Fund 100 %

Manufacturing cost 100% 5th

7th

11th

13th

17th

19th

63 %

54 %

10 %

6.1 %

6.7 %

4.8 %

With chokes 100 % load Fund 100 %

Manufacturing cost 120% 5th 30 %

7th

11th

12 %

8.9 %

13th 5.6 %

17th 4.4 %

19th 4.1 %

© ABB Group April 12, 2010 | Slide 37

Summary 12 Pulse Polygon Transformer 100 % load Fund 100 %

5th 11 %

Manufacturing cost 200% 7th 5.8 %

11th 6.2 %

Double wound Transformer 100 % load Fund 100 %

13th 4.7 %

17th 1.7 %

19th 1.4 %

Manufacturing cost 210%

5th

7th

11th

13th

17th

19th

3.6 %

2.6 %

7.5 %

5.2 %

1.2 %

1.3 %

© ABB Group April 12, 2010 | Slide 38

19

Summary 24 Pulse Manufacturing cost 250% Fund 100 %

5th 4.0 %

7th

11th

13th

17th

19th

2.7 %

1.0 %

0.7 %

1.4 %

1.4 %

Active Rectifier Manufacturing cost 250% Fund 100 %

5th 2.6 %

7th 3.4 %

11th 3.0 %

13th

17th

0.1 %

2.1 %

19th 2.2 %

© ABB Group April 12, 2010 | Slide 39

Summary

Filter Solutions Single arm tuned

Not normally used for new installations

Multi arm tuned

Costs Increase

Most suited to DC drives

Active

Most suited to multiple small drives

© ABB Group April 12, 2010 | Slide 40

20

Comparison of solutions Example 1 6 x 30 kW Drives - 5 Duty 1 Standby 6 x 6 Pulse drives plus 1 x AHF 6 x Active Rectifier AC Drive

100 % 125 %

Example 2 4 x 132 kW Drives - 3 Duty 1 Standby 4 x 6 Pulse drives plus 1 x AHF 4 x 12 Pulse drives 4 x Active Rectifier AC Drive

100 % 75 % 82 %

© ABB Group April 12, 2010 | Slide 41

Comparison of solutions Example 3 3 x 250 kW Drives - 2 Duty 1 Standby 3 x 6 Pulse drives plus 1 x AHF 3 x 12 Pulse drives 3 x Active Rectifier AC Drive

100 % 95 % 96 %

Example 2 3 x 500 kW Drives - 2 Duty 1 Standby 3 x 6 Pulse drives plus 1 x AHF 3 x 12 Pulse drives plus 1 x AHF 3 x Active Rectifier AC Drive

100 % 95 % 97 %

© ABB Group April 12, 2010 | Slide 42

21

22