1.AC Harmonic Filters
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Transcript of 1.AC Harmonic Filters
7/30/2019 1.AC Harmonic Filters
http://slidepdf.com/reader/full/1ac-harmonic-filters 1/38
Ac harmonic filters
7/30/2019 1.AC Harmonic Filters
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FILTER
FILTER
HVDC Main Components
T8396
7/30/2019 1.AC Harmonic Filters
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AC Harmonic Filters
7/30/2019 1.AC Harmonic Filters
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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
7/30/2019 1.AC Harmonic Filters
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Idealised harmonic currents
Practical harmonic currentsCharacteristic harmonics
Theoretically cancelled harmonics
Non-characteristic harmonics
Types of Harmonic
T8395
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Idealised Current Waveforms….
T8397
7/30/2019 1.AC Harmonic Filters
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Combined Waveform…..
T8399
7/30/2019 1.AC Harmonic Filters
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12 Pulse
Practical Harmonic Currents….
T8402
7/30/2019 1.AC Harmonic Filters
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λ λ
π ω ω ω ω ω
λ
π ω ω ω ω ω
/
(cos cos cos cos cos ...
/
(cos cos cos cos cos ...
I I D
t t t t t
I I D
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
7/30/2019 1.AC Harmonic Filters
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I I D t t t
t t
= − +
− +
4 3 1
1 1 1 1
1
1 3 1 3
1
2 32 3
1
2 52 5
π ω ω ω
ω ω
( c o s c o s c o s
c o s c o s . . .
Fourier Analysis
T8400
7/30/2019 1.AC Harmonic Filters
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9
8
7
6
5
4
3
2
1
10 3020 40
Overlap angle (degrees)
I11
I1
11th Harmonic as a Percentage of Fundamental
T8404
7/30/2019 1.AC Harmonic Filters
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0.2 0.4 0.6 0.8 1.0
1
2
3
4
5
H
a r m o n i c l i n e c u r r e n t % o
f
r a t e d f u n d a m
e n t a l
Transmitted power (PU)
11th
13th
Characteristic Harmonic Generation
T8405
7/30/2019 1.AC Harmonic Filters
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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)
H a r m o n i c l i n e c u r r e n t % o
f
r a t e d f u n d a m e n t a l
Theoretically Cancelled Harmonic Generation
T8407
7/30/2019 1.AC Harmonic Filters
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100
10
1.0
0.1
0.01
0.00110 20 30 40 50
Harmonic Number
In
I1%
Typical Spectrum…
T8409
7/30/2019 1.AC Harmonic Filters
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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
7/30/2019 1.AC Harmonic Filters
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Filter
Zfn
System
ZSnIcn
Ifn
VSn
ISn
T8378
7/30/2019 1.AC Harmonic Filters
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Rmin
X ( O h m s )
R(Ohms)
400kV System Harmonic Impedance
T8381
Rmax
2
7/30/2019 1.AC Harmonic Filters
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Sasaram Filters
T8379
400kV
Double Damped
Filter
400kV
Double Tuned Filter
7/30/2019 1.AC Harmonic Filters
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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 onlywhen filter is de-energised and earthed.
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AC Filter Layouts Double Damped Filter
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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 1 2 14 1 6 18 2 0 22 24 26 28 3 0 32 34 3 6 38 40 42 4 4 46 48 50 5 2 54
Harm onic
A d m i t a n c e
3/13th Double-Frequency Filter
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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
A d m i t a n c e
11/25th Double-Frequency Filter
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Single frequencytuned filter
2nd Orderbroadband
damped filter
3rd Orderbroadband
damped filter
‘C’ Typebroadband
damped filter
Types of Filter
T8412
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Advantages
Maximum attenuation at single harmonic
Low loss
Disadvantages
May be de-tuned
Off-circuit adjustment
Single Tuned
T8413
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f1 f0 f2 Frequency
High Q
Low Q
Y
Effect of De-tuning
T8414
7/30/2019 1.AC Harmonic Filters
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Advantages
Attenuation over a spectrum of harmonics
Less sensitive to de-tuning Disadvantages
Needs higher Mvar to achieve same performance as singletuned
Additional losses in resistor
2nd Order Damped
T8416
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Tuned / Damped Filters
f1 f0 f2 Frequency
Damped filter
Tuned filter
Filter admittance
T8417
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Single frequency
tuned filter
2nd Order
broadband
damped filter
3rd Order
broadband
damped filter
‘C’ Type
broadband
damped filter
Types of Filter
T8418
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Advantages
Lower losses in resistor
Disadvantages Poorer performance than 2nd order
Additional cost of capacitor
3rd Order Damped
T8419
7/30/2019 1.AC Harmonic Filters
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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
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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
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Double Tuned Double Tuned
Double Tuned Filters
T8423
7/30/2019 1.AC Harmonic Filters
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0.03
0.02
0.01
0
-0.01
0 10 20 30 40 50
Harmonic
A d m i t t a n c e ( m h o s )
G
B
Admittance Characteristic
(G= conductance, B= susceptance)
T1774
7/30/2019 1.AC Harmonic Filters
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Main Capacitor
Corona Rings
Base Insulators
Horizontal MountedCans
LV Terminal
HV Terminal
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Auxiliary Capacitor
Base Insulators
Steel Frames
HV terminal
LV terminal
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Reactors
Spiders
Terminal
Coil
Base
Insulators
Pedestals
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Resistors
Roof
Base
Insulators
Bushings
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Thank You