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Ac harmonic filters

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Page 1: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Ac harmonic filters

Page 2: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

FILTER

FILTER

HVDC Main Components

T8396

Page 3: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

AC Harmonic Filters

Page 4: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Idealised harmonic currents

� Practical harmonic currents

� Characteristic harmonics

� Theoretically cancelled harmonics

� Non-characteristic harmonics

Types of Harmonic

T8395

Filter Design Objectives

�Limit voltage distortion

�Minimise reactive power imbalance

�Minimise losses

�Improve system performance

Page 5: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Idealised harmonic currents

� Practical harmonic currents

� Characteristic harmonics

� Theoretically cancelled harmonics

� Non-characteristic harmonics

Types of Harmonic

T8395

Page 6: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Idealised Current Waveforms….

T8397

Page 7: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Combined Waveform…..

T8399

Page 8: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

12 Pulse

Practical Harmonic Currents….

T8402

Page 9: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

λ λ

πω ω ω ω ω

λ

πω ω ω ω ω

/

(cos cos cos cos cos ...

/

(cos cos cos cos cos ...

I ID

t t t t t

I ID

t t t t t

= − + − +

= + − + −

2 3 1

55

1

77

1

1111

1

1313

2 3 1

55

1

77

1

1111

1

1313

Fourier Analysis

T8398

Page 10: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

I ID

t t t

t t

= − +

− +

4 3 1

1 11 1

1

1 31 3

1

2 32 3

1

2 52 5

πω ω ω

ω ω

( c o s c o s c o s

c o s c o s . . .

Fourier Analysis

T8400

Page 11: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

9

8

7

6

5

4

3

2

1

10 3020 40Overlap angle (degrees)

I11

I1

11th Harmonic as a Percentage of Fundamental

T8404

Page 12: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

0.2 0.4 0.6 0.8 1.0

1

2

3

4

5

Harm

onic

lin

e c

urr

ent %

of

rate

d fundam

enta

l

Transmitted power (PU)

11th

13th

Characteristic Harmonic Generation

T8405

Page 13: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

0.5

0.4

0.3

0.2

0.1

0.2 0.4 0.6 0.8 1.0

5th

7th

Transmitted Power(PU)

Harm

onic

lin

e c

urr

ent %

of

rate

d fundam

enta

l

Theoretically Cancelled Harmonic Generation

T8407

Page 14: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

100

10

1.0

0.1

0.01

0.00110 20 30 40 50

Harmonic Number

In

I1%

Typical Spectrum…

T8409

Page 15: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Orders n = 1, 2, 3, 4 etc.

� AC system unbalance (NPS)

� Transformer reactance phase unbalance

� Pre-existing distortion

� firing angle jitter

Non - Characteristic Harmonics

T8408

Page 16: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Filter

Zfn

System

ZSnIcn

Ifn

VSn

ISn

T8378

Page 17: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Rmin

X(O

hm

s)

R(Ohms)

400kV System Harmonic Impedance

T8381

Rmax

2

Page 18: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Sasaram Filters

T8379

400kV

Double Damped

Filter

400kV

Double Tuned Filter

Page 19: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

AC Filter Layouts…

� Components mounted on the ground

� Insulation and magnetic clearances

� Two types of harmonic filter

� Double damped filter

� Double tuned filter

� Key Interlocking System for safety - to permit access only when filter is de-energised and earthed.

Page 20: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

AC Filter Layouts Double Damped Filter

Page 21: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Admittance vs frequency for 400kV 112Mvar 3/13 double frequency filter

0.0000

0.0050

0.0100

0.0150

0.0200

0.0250

0.0300

0.0350

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54

Harm onic

Adm

itance

3/13th Double-Frequency Filter

Page 22: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Admittance vs frequency for 400kV 112Mvar 11/25 double frequency filter

0.0000

0.0050

0.0100

0.0150

0.0200

0.0250

0.0300

0.0350

0.0400

0.0450

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54

Harm onic

Adm

itance

11/25th Double-Frequency Filter

Page 23: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Single frequencytuned filter

2nd Order broadband

damped filter

3rd Order broadband

damped filter

‘C’ Type broadband

damped filter

Types of Filter

T8412

Page 24: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Advantages

� Maximum attenuation at single harmonic

� Low loss

� Disadvantages

� May be de-tuned

� Off-circuit adjustment

Single Tuned

T8413

Page 25: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

f1 f0 f2 Frequency

High Q

Low Q

Y

Effect of De-tuning

T8414

Page 26: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Advantages

� Attenuation over a spectrum of harmonics

� Less sensitive to de-tuning

� Disadvantages

� Needs higher Mvar to achieve same performance as single tuned

� Additional losses in resistor

2nd Order Damped

T8416

Page 27: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Tuned / Damped Filters

f1 f0 f2 Frequency

Damped filter

Tuned filter

Filter admittance

T8417

Page 28: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Single frequency

tuned filter

2nd Order

broadband

damped filter

3rd Order

broadband

damped filter

‘C’ Type

broadband

damped filter

Types of Filter

T8418

Page 29: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Advantages

� Lower losses in resistor

� Disadvantages

� Poorer performance than 2nd order

� Additional cost of capacitor

3rd Order Damped

T8419

Page 30: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Advantages

� lower losses in resistor

� Better performance than 3rd order

� Disadvantages

� Poorer performance than 2nd order

� Additional cost of capacitor

� May require off-circuit adjustment

C - Type

T8421

Page 31: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

� Advantages

� Only one HV capacitor bank

� Only one reactor subject to HV tests

� Reduced number of filter arms

� No minimum size

� Improved redundancy

� Low fundamental losses (double tuned)

Multiple Tuned Filters

T8422

Page 32: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Double Tuned Double Tuned

Double Tuned Filters

T8423

Page 33: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

0.03

0.02

0.01

0

-0.01

0 10 20 30 40 50

Harmonic

Adm

itta

nce (m

hos)

G

B

Admittance Characteristic(G= conductance, B= susceptance)

T1774

Page 34: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Main Capacitor

Corona Rings

Base Insulators

Horizontal Mounted

Cans

LV Terminal

HV Terminal

Page 35: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Auxiliary Capacitor

Base Insulators

Steel Frames

HV terminal

LV terminal

Page 36: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Reactors

Spiders

Terminal

Coil

Base

Insulators

Pedestals

Page 37: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

Resistors

Roof

Base

Insulators

Bushings

Page 38: Ac harmonic filters - USAID SARI/Energy Integration · AC Harmonic Filters. Idealised harmonic currents Practical harmonic currents Characteristic harmonics Theoretically cancelled

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