HARMONIC TREATMENT IN INDUSTRIAL POWER .ppt

HARMONIC TREATMENT IN INDUSTRIAL POWER SYSTEMS

Presented by Stefanos Manias

CONTACT CONTA CT IN INORMAT ORMATION ION

Stefanos N! Manias Nationa" Te#$ni#a" Uni%ersity of At$ens P$one& '()1)*++,(-)( A.& '()1)*++,(-/( E*0ai"& 0anias#entra"!nt2a!3r  Mai"in3 Address Nationa" Te#$ni#a" Uni%ersity of At$ens De4art0ent of E"e#tri#a" and Co042ter En3ineerin3 /5 Iroon Po"yte#$nio2 Str5 1-++( 6o3rafo2 At$ens5 7ree#e

PLAN O PRESE PRESENTA NTAT TION

1!

DEINITIONS

,!

CATE7ORIES O POWER 8UALITY 9A 9ARIATIONS RIATIONS

(!

HARMONIC DISTORTION SOURCES IN INDUSTRIAL POWER SYSTEMS

:!

EECTS O HARMONICS ON ELECTRICAL E8UIPMENT

-!

HARMONIC MEASUREMENTS IN INDUSTRIAL POWER SYSTEMS

;!

HARMONIC STA STANDARDS NDARDS

+!

HARMONIC MITI7ATIN7 TECHNI8UES

or f2se fai"2res in t$e #a4a#itor or ot$er e"e#tri#a" e2i40ent!



a"se tri44in3 of #ir#2it brea@ers ad 4rote#ti%e re"ays!

HARMONIC SOURCES a C2rrent So2r#e non"inear "oad

T$yristor re#tifier for d# dri%es5 $eater dri%es5 et#!

Per*4$ase e2i%a"ent #ir#2it of t$yristor re#tifier 

b 9o"ta3e so2r#e non"inear "oad

Diode re#tifier for a# dri%es5 e"e#troni# e2i40ent5 et#

Per*4$ase e2i%a"ent #ir#2it of diode re#tifier 

INPUT CURRENT O DIERENT NOLINEAR LOADS

TYPE O NONLINEAR LOAD

TYPICAL WAREORM

THD

1.0

1*F Un#ontro""ed Re#tifier 

armonic Emissions standards were first pu+lished as IEC ,,-2 %/2 and applied onl4 to household appliances It was re*ised and reissued in %/$ and %//, with the applica+ilit4 e7panded to include all euipment with input current ≤ %'5 per phase >owe*er# until Januar4 %st# 200% a transition period is in effect for all euipment not co*ered +4 the standard prior to %/$ - The o+?ecti*e of EN '%000-.-2 !harmonics) is to test the euipment under the conditions that will produce the ma7imum harmonic amplitudes under normal operatin conditions for each harmonic component To esta+lish limits for similar t4pes of harmonics current distortion# euipment under test must +e cateori1ed in one of the followin four classes

CLASS*A& =alanced three-phase euipment and all other euipment e7cept that stated in one of the remainin three classes CLASS*G& Porta+le electrical tools# which are hand held durin normal operation and used for a short time onl4 !few minutes)   CLASS*C& @ihtin euipment includin dimmin de*ices CLASS*D& Euipment ha*in an input current with special wa*e shape ! eeuipment with off-line capacitor-rectifier 5C input circuitr4 and switch Aode power Supplies) and an acti*e input power '00B

*  5dditional harmonic current testin# measurement techniues and instrumentation uidelines for these standards are co*ered in IEC %000-"-$



IEEE -1/*1//, United States Standards on $ar0oni# "i0its

-

IEEE limits ser*ice entrance harmonics

-

Bith this approach the costumerDs current distortion is limited +ased on relati*e si1e of the load and the power supplierDs *oltae distortion +ased on the *oltae le*el

The IEEE standard ,%/-%//2 limits the le*el of harmonics at the customer ser*ice entrance or Point of Common Couplin !PCC)

IEEE ,%/ and IEC %000-.-2 appl4 different philosophies# which effecti*el4 limit harmonics at different locations IEEE ,%/ limits harmonics primaril4 at the ser*ice entrance while IEC %000-.-2 is applied at the terminals of end-user euipment Therefore# Therefore# IEC limits will tend to reduce harmonic-related losses in an industrial plant wirin# while IEEE harmonic limits are desined to pre*ent interactions +etween neih+ors and the power s4stem

POWER 8UALITY STANDARDS   IEEE -1/*1//, STANDARDS TAGLE I CURRENT DISTORTION LIMITS OR 7ENERAL DISTRIGUTION SYSTEMS B1,)*;/))) 9

Is# >IL

11

11$1+

1+$,( ,($(-

(-$

TDD

,)

:!)

,!)

1!-

) !;

) !(

-!)

,)-)

+!)

(!-

,!-

1 !)

) !-

t!t ) ⋅ ( − D  #C) ? t!t

#! > t!t

=

+ D#>t!t − D

1 #! C



' !

=

1

B:(

#C

1

B::

2#!

T$e e2ation for in#an be 2sed to deter0ine t$e e2i%a"ent syste0 i04edan#e for different fre2en#ies! T$e $ar0oni# 4rod2#in3 "oads #an resonate B4ara""e" resonan#e5 t$e abo%e e2i%a"ent #ir#2it! Desi3natin3 t$e 4ara""e" resonant fre2en#y by #Brad>se# or BH6 ' ! and e2atin3 t$e ! ind2#ti%e and #a4a#iti%e rea#tan#es!

-

>armonic current components that are close to the parallel resonant freuenc4 are amplified >iher order harmonic currents at the PCC are reduced +ecause the capacitors are low impedance at these freuencies The fiure +elow shows the effect of addin capacitors on the "0 Holts +us for power factor correction

This fiure shows that +4 addin some t4pical si1es of power factor correction capacitors will result in the manification of the ,th  and $th  harmonic components# which in turns ma3es it e*en more difficult to meet the IEEE ,%/-%//2 harmonic current standards  - Power factor correction capacitors should not +e used without turnin reactors in case the ad?usta+le speed dri*es are K%0L of the plant load

E.AMPLE @et us e7amine an industrial plant with the followin data6 -

Aedium *oltae 9 20H @@

-

@ow *oltae 9 0" H@@

-

Utilit4 three phase short circuit power 9 2,0 AH5

-

For as4mmetrical current# the

@

? 

ratio of s4stem impedance

= 2.4

The Transformer is rated6 1))) J9A5 ,) J9*:)) Y>,() 9 R42 K 15

.42 K +

- The s4stem freuenc4 is6 f s4s 9 ,0 >M - For power factor correction capacitors the followin cases are e7amined6 a!

,)) J9AR

b!

:)) J9AR

#!

;)) J9AR

d!

t!t

=

0.011791 2 ⋅  ⋅ 50

= 37.55 ⋅10−6 +

Case a&

@$

=

C ' !

=

=

1000 ⋅ ( 0.4)

2

= 0.8 J

200 1

2 ⋅ 50 ⋅ 0.8

= 3.98 ⋅10−3  1

2 ⋅

37.50 ⋅10

−6 ⋅ 3.98 ⋅10−3

= 412.18+

or ,)) J9AR5 t$e $ar0oni# order at ?$i#$ 4ara""e" resonan#e o##2rs is&



= 412.18 50 = 8.24

Case b&

@$

=

1000 ⋅ ( 0.4) 400

C = 7.96 ⋅10 ' !

2

= 0.4 J

−3 

= 291.45+

 = 5.83 Case #&

@$

=

1000 ⋅ ( 0.4) 600

C = 11.94 ⋅10

−3 

= 237.97+  = 4.76

' !

2

= 0.267 J

Case d&

@$

=

1000 ⋅ ( 0.4)

2

800

= 0.2 J

− C = 15.92 ⋅10 3  ' !

= 206.08+

 = 4.12 It is #"ear for t$e abo%e syste0 t$at in t$e ;)) J9AR #ase5 t$ere eists a 4ara""e" resonant fre2en#y ' !#"ose to t$e - t$ $ar0oni#!

POWER ACTOR CORRECTION AND HARMONIC TREATMENT USIN7 TUNED ILTERS -

=asic confiuration of a tuned .- capacitor +an3 for power factor correction and harmonic treatment

 Simple and cheap filter 



 Pre*ents of current harmonic manification



-

  IN OE TO 5HOI >5AONIC A5QNIFIC5TION BE C>OOSE 5 TUNE FE8UENCR  FIT> >5AONIC !ie "$)

-

The freuenc4 characteristic of the tuned filter at "$ is shown +elow

 5s it can +e seen from the a+o*e fiure sinificant reduction of the ,th harmonic is achie*ed Aoreo*er# there is some reduction for all the other harmonic components

The sinle phase eui*alent circuit of the power distri+ution s4stem with the tuned filter is shown +elow

Usin the a+o*e circuit the followin euations hold6

' !%

=

1 1

2  ( >'  ⋅ C ) 2 1

> '  =

C ⋅ ( 2 ' !% ) 2

K Resonant fre2en#y of t$e series fi"ter  B:-

=

2 '  ⋅ @ $

( 2 ' !% ) 2

=

'  ⋅1000 ( /$;: ) 2 2  ⋅ ( ' !% ) 2 ⋅ /? $;:

B:;

T$e ne? 4ara""e" #o0bination is $a%in3 resonant fre2en#y ?$en

# ! > t!t ' !

=

+ # ! > '  −

1 #!C

=0

B4ara""e" resonan#e

1 2 [ ( > t!t

+ >'  ) ⋅ C]

1

2

K resonan#e fre2en#y of t$e B:+ e2i%a"ent distrib2tion #ir#2it

A"so

+ D#> t!t I '  = I  ⋅ ? t!t + D[ #> t!t + #> '  − 1 #C] ? t!t

 B: '  − 1  #C )

? t!t

+ D [ #> t!t + #>'  − 1 #C]

= I% ⋅ ( ? t!t + D#> t!t )

=

B-)

( ? t!t + D#> t!t ) ⋅    D#>'  − D

  ? t!t + D#> t!t + D#>'  − D

( ? t!t + D#> t!t ) ⋅    D#>'  − D

B:/

    #C   = 1

1

#C

    # C     = 1     ? t!t + D  #> t!t + #> '  −   # C     1

B-1

As it ?as dis#2ssed before Se"e#tin3 ' ! Wit$

> '  =

J9#a4K )!: 5

50 ⋅1000 ⋅ ( 0.4 )

2

2 ⋅  ⋅ ( 235) 2 ⋅ 600

= 235+

or :!+ t$ $ar0oni#

J9AR#a4K ;))

= 68.45 ⋅10−6 + = 38.45K+

 T$e ne? 4ara""e" #o0bination is $a%in3 resonant fre2en#y&

' ! ?it$

' ! = 

=

1 2⋅⋅

[ ( > t!t + >'  ) ⋅ C]

= 37.55 ⋅10−6 + > '  = 38.45 ⋅10 −6 + C = 11.94 ⋅10−3  > t!t

1 2 ⋅  ⋅ 76 ⋅10 −6 ⋅11.94 ⋅10 −3

= 167.16  50 = 3.43

?e $a%e

= 167.16+

B?it$o2t Lf  ?as :!+;

T$e fo""o?in3 tab"e s$o?s t$e %ariation of Para""e" resonant fre2en#y Wit$ and ?it$o2t resonant ind2#tor 

Para""e" Resonant f ) J9AR

CB0

Wit$o2t Lf 

,))

(!/<

SIMULINJ

SIMULINJ RESULTS

SIMULINJ RESULTS

ACTI9E ILTERIN7

Para""e" ty4e

Series ty4e

RESULTS O ACTI9E ILTERIN7 2,00

.0

%,00

I 5U

2,

,00

       %    I

20 %,

   L    T

-,00

%0

-%,00

,

-2,00

0

0

,

%0

%,

20

2,

.0

.,

2

"0

,

-

%%

%"

%$

20

2.

>armonics

Time msU

In42t #2rrent of a ;*42"se Re#tifier dri%in3 a DC 0a#$ine ?it$o2t any in42t fi"terin3 ,000

.,L .0L

   T 2,00    p    m    o    c 0    a    n   4        I -2,00

2,L

    20L    %    I    L    T %,L %0L ,L

-,000

0L

0

%0

20

.0

Time msU

In42t #2rrent ?it$ A#ti%e i"terin3

"0

2

,

-

%%

%"

>armonics

%$

20

2.

%000

%" %2

,00        H    T    U

%0

       %    U '    L    T

0

"

-,00

2

-%000

0

0

,

%0

%,

20

2,

.0

.,

"0

2

,

-

%%

Time msU

%"

%$

20

2.

>armonics

Ty4i#a" ;*42"se dri%e %o"ta3e ?a%efor0 %000

%" %2

,00    H    T    U

%0         U    L    T '

0

"

-,00

2 -%000

0 0

,

%0

%, 20 2, Time msU

.0

.,

"0

2

,

9o"ta3e so2r#e i04ro%e0ent ?it$ a#ti%e fi"terin3



%%

%" %$ >armonics

20

2.

SHUNT ACTI9E ILTERS =4 insertin a parallel acti*e filter in a non-linear load location we can in?ect a harmonic current component with the same amplitude as that of the load in to the 5C s4stem

 LF 

C

Eui*alent circuit

AD9ANTA7ES O THE SHUNT OR PARALLEL ACTI9E ILTER



 @ow implementation cost



 o not create displacement power factor pro+lems and utilit4 loadin



  Suppl4 inductance @ S# does not affect the harmonic compensation of parallel acti*e filter s4stem



 Simple control circuit



  Can damp harmonic propaation in a distri+ution feeder or +etween two distri+ution feeders



 Eas4 to connect in parallel a num+er of acti*e filter modules in order to achie*e hiher power reuirements



 Eas4 protection and ine7pensi*e isolation switchear



 Eas4 to +e installed



 Pro*ides immunit4 from am+ient harmonic loads

WA9EORMS O THE PARALLEL ACTI9E ILTER

So2r#e %o"ta3e

Load #2rrent

So2r#e #2rrent

A! ! o2t42t #2rrent

PARALLEL ACTI9E ILTER E8UATIONS

IC

IS

L1

=0

=

> >

S

+

= LI > L

1− L

=1



⋅ I >+ +

B-,

S >

S

+

1

⋅

B-(

1− L

> I>

1− L >

=

S +

1− L

1− L

>

If 

⋅ I>+ +

1− L 

>>

S

S

S >

+

B-:

1− L

B--



Then the a+o*e euations +ecome

IC IS

≈

=

B-;

I >

(1 − L ) I >+

+

(1 − L )

-S >

≈

0

B-+

I >

=

I >+

+

-S

B-

E2ation B-- is t$e re2ired #ondition for t$e 4ara""e" A!! to #an#e" t$e "oad $ar0oni# #2rrent! On"y 7 #an be 4redesi3n by t$e A!! ?$i"e 6s and 6L are deter0ined by t$e syste0!

or 42re #2rrent so2r#e ty4e of $ar0oni# so2r#e  >

>>

S

and #onse2ent"y e2ations B-( and B-- be#o0e

IS

=

(1 − L )

1− L

+



B-/

1

S

K So2r#e i04edan#e

I >+

K Is t$e e2i%a"ent $ar0oni# #2rrent so2r#e

B;)

 > K E2i%a"ent "oad i04edan#e L K e2i%a"ent transfer f2n#tion of t$e a#ti%e fi"ter  E2ation B-/ s$o?s t$at t$e #o04ensation #$ara#teristi#s of t$e A!! are not inf"2en#ed by t$e so2r#e i04edan#e5 6 s! T$is is a 0aor ad%anta3e of t$e A!! ?it$ res4e#t to t$e 4assi%e ones!

&C C

 The C +us nominal *oltae# -&C# must +e reater than or eual to line *oltae pea3 in order to acti*el4 control i C .  The selection of the interface inductance of the acti*e filter is +ased on the compromise of 3eepin the output current ripple of the in*erter low and the same time to +e a+le to trac3 the desired source current  The reuired capacitor *alue is dictated +4 the ma7imum accepta+le *oltae ripple 5 ood initial uess of C is6 

m;M C≥

2

t

∫ 0 iC&t

 5lso

>

NCm;M

n 9 pea3 line-neutral *oltae &C 9 C *oltae of the C +us of the in*erter  i> 9 @ine phase current NCm;M

9 ma7imum accepta+le *oltae ripple#

iC 9 Phase current of the in*erter 

≥

3

&C − n

m;M

&i> &t

P*8 THEORY For identif4in the harmonic currents in eneral the method of computin instantaneous acti*e and reacti*e power is used Transformation of the three-phase *oltaes  u    and   and the threephase load currents i >  i >u and i > into V-W orthoonal coordinate

 H    =  O

i >H  i  =  >O 

2 3

2 3

1 − 1  2 0 32 

u   − 1 2        − 3  2   

1 − 1 2 0 32 

 i >u  − 1 2      i >  − 3  2 i > 

Then accordin to  : -  theor4# the instantaneous real power : > and the instantaneous imainar4 !reacti*e) power  > are calculated

 :>   H   = −   >  O

O  i >H 





H  i >O 

where

 : >

= :> + : > +  :> =

DC ' "o? fre2en#y #o04! ' $i3$ fre! #o04!

>

= > +  > +  > =

DC ' "o? fre2en#y #o04! ' $i3$ fre! #o04!



The con*entional acti*e power is correspondin to :># the con*entional reacti*e  power to > and the neati*e seuence to the 2 f components of  : > and  > The commands of the three-phase compensatin currents in?ected +4 the ∗ and ∗ are i*en +46 shunt acti*e conditioner# i∗ # i i C Cu C

 i∗Cu  ∗   iC  = i∗C   

2 3

 1 − 1  2  − 1  2 −

  H  32   - O 3  2  0

 :∗ 9 Instantaneous real power command ∗

 9 Instantaneous reacti*e power command

−1

 :∗     H  ∗  O 

S2bstit2tin3 ∗

 : 

∗

  = : > ⇒  = >  

C2rrent Har0oni#s #o04ensation is a#$ie%ed

∗

  = : ⇒ >   ∗   =  > + >  

 :

C2rrent Har0oni#s and "o? fre2en#y %ariation Co04onents of rea#ti%e 4o?er #o04ensation

  = : > + : > C2rrent Har0oni#s and "o? fre2en#y %ariation ⇒   Co04onents of a#ti%e and rea#ti%e 4o?er #o04ensation ∗  = > +  >   ∗

 :

HARMONIC DETECTION METHODS

i

Load #2rrent dete#tion i AK iL$ It is s2itab"e for s$2nt a#ti%e fi"ters ?$i#$ are insta""ed near one or 0ore non*"inear "oads!

ii

S244"y #2rrent dete#tion i AK JS iS$ Is t$e 0ost basi# $ar0oni# dete#tion 0et$od for series a#ti%e fi"ters a#tin3 as a %o"ta3e so2r#e % A!

iii 9o"ta3e dete#tion It is s2itab"e for s$2nt a#ti%e fi"ters ?$i#$ are 2sed as Unified Po?er 82a"ity Conditioners! T$is ty4e of A#ti%e i"ter is insta""ed in 4ri0ary 4o?er distrib2tion syste0s! T$e Unified Po?er 82a"ity Conditioner #onsists of a series and a s$2nt a#ti%e fi"ter!

SHUNT ACTI9E ILTER CONTROL

a S$2nt a#ti%e fi"ter #ontro" based on %o"ta3e dete#tion

Usin3 t$is te#$ni2e t$e t$ree*4$ase %o"ta3es5 ?$i#$ are dete#ted at t$e 4oint of insta""ation5 are transfor0ed to & and  on t$e d #oordinates! T$en t?o first   order $i3$*4ass fi"ters of -H6 in order to etra#t t$e a# #o04onents & and   ! Net t$e a# #o04onents are a44"ied to t$e in%erse d fro0 & and transfor0ation #ir#2it5 so t$at t$e #ontro" #ir#2it to 4ro%ide t$e t$ree*4$ase $ar0oni# %o"ta3es at t$e 4oint of insta""ation! ina""y5 a04"ifyin3 ea#$ $ar0oni# %o"ta3e by a 3ain J% 4rod2#es ea#$ 4$ase #2rrent referen#e!

∗

i (

= Q  ⋅ 

T$e a#ti%e fi"ter be$a%es "i@e a resistor 1>J9  o$0s to t$e eterna" #ir#2it for $ar0oni# fre2en#ies ?it$o2t a"terin3 t$e f2nda0enta" #o04onents! ∗ T$e #2rrent #ontro" #ir#2it #o04ares t$e referen#e #2rrent i (?it$ t$e a#t2a" #2rrent of t$e a#ti%e fi"ter i ( and a04"ifies t$e error by a 3ain JI ! Ea#$ 4$ase %o"ta3e dete#ted at t$e 4oint of insta""ation5 % is added to ea#$ 0a3nified error si3na"5 t$2s #onstit2tin3 a feed for?ard #o04ensation in order to i04ro%e #2rrent #ontro""abi"ity! As a res2"t5 t$e #2rrent #ontro""er yie"ds t$ree*4$ase %o"ta3e ∗ referen#es! T$en5 ea#$ referen#e %o"ta3e i is #o04ared ?it$ a $i3$ fre2en#y trian32"ar ?a%efor0 to 3enerate t$e 3ate si3na"s for t$e 4o?er se0i#ond2#tor de%i#es!

b Referen#e #2rrent #a"#2"ation s#$e0e 2sin3 so2r#e #2rrents Bi s5 "oad #2rrents Bi L and %o"ta3es at t$e 4oint of insta""ation B% S!

(*F HYGRID ACTI9E*PASSI9E ILTER Co04ensation of #2rrent $ar0oni#s and dis4"a#e0ent 4o?er fa#tor #an be a#$ie%ed si02"taneo2s"y!

In t$e #2rrent $ar0oni# #o04ensation 0ode5 t$e a#ti%e fi"ter i04ro%es t$e fi"terin3 #$ara#teristi# of t$e 4assi%e fi"ter by i04osin3 a %o"ta3e $ar0oni# ?a%efor0 at its ter0ina"s ?it$ an a04"it2de

C

= QIS

If t$e AC 0ains %o"ta3e is 42re sin2soida"5 t$en

IS I>

=

 Q + 

+ S

T+,i

=

      ∑ I> Q +  + S      =2 IS1

 THDi de#reases if J in#reases!  T$e "ar3er t$e %o"ta3e $ar0oni#s 3enerated by t$e a#ti%e fi"ter a better fi"ter #o04ensation is obtained!  A $i3$ %a"2e of t$e 2a"ity fa#tor defines a "ar3e band ?idt$ of t$e 4assi%e fi"ter5 i04ro%in3 t$e #o04ensation #$ara#teristi#s of t$e $ybrid to4o"o3y!  A "o? %a"2e of t$e 2a"ity fa#tor and>or a "ar3e %a"2e in t$e t2ned fa#tor in#reases t$e re2ired %o"ta3e 3enerated by t$e a#ti%e fi"ter ne#essary to @ee4 t$e sa0e #o04ensation effe#ti%eness5 ?$i#$ in#reases t$e a#ti%e fi"ter rated 4o?er!

Dis4"a#e0ent 4o?er fa#tor #orre#tion is a#$ie%ed by #ontro""in3 t$e %o"ta3e dro4 a#ross t$e 4assi%e fi"ter #a4a#itor!

C

= OT

Dis4"a#e0ent 4o?er fa#tor #ontro" #an be a#$ie%ed sin#e at f2nda0enta" fre2en#y t$e 4assi%e fi"ter e2i%a"ent i04edan#e is #a4a#iti%e!

HYGRID ACTI9E*PASSI9E ILTER

Sin3"e*4$ase e2i%a"ent #ir#2it

Sin3"e*4$ase e2i%a"ent #ir#2it for -t$ Har0oni#

T$is a#ti%e fi"ter dete#ts t$e - t$ $ar0oni# #2rrent #o04onent t$at f"o?s into t$e 4assi%e fi"ter and a04"ifies it by a 3ain J in order to deter0ine its %o"ta3e referen#e ?$i#$ is 3i%en by

∗

= Q ⋅ i 5

As a res2"t5 t$e a#ti%e fi"ter a#ts as a 42re resistor of J o$0s for t$e - t$ $ar0oni# %o"ta3e and #2rrent! T$e i04edan#e of t$e $ybrid fi"ter at t$e - t$ $ar0oni# fre2en#y5 6- is 3i%en by

5

Q  < 0

=  D5#>  +

1  D5#C 

+ r '  + Q 

T$e a#ti%e fi"ter 4resents a ne3ati%e resistan#e to t$e eterna" Cir#2it5 t$2s i04ro%in3 t$e 8 of t$e fi"ter!

Q  = −r 

US5

= 0

IS5

=

1  D5#> T

S5

CONTROL CIRCUIT T$e #ontro" #ir#2it #onsists of t?o 4arts a #ir#2it for etra#tin3 t$e -t$ #2rrent $ar0oni# #o04onent fro0 t$e 4assi%e fi"ter i  and a #ir#2it t$at ad2sts a2to0ati#a""y t$e 3ain J! T$e referen#e %o"ta3e for t$e a#ti%e fi"ter ∗

 

= Q ⋅ i 5

HARMONIC*E.TRACTIN7 CIRCUIT T$e etra#tin3 #ir#2it dete#ts t$e t$ree*4$ase #2rrents t$at f"o? into t$e 4assi%e fi"ter 2sin3 t$e AC #2rrent transfor0ers and t$en t$e * #oordinates are transfor0ed to t$ose on t$e d*3 #oordinates by 2sin3 a 2nit %e#tor B#os-t5 sin-t ?it$ a rotatin3 fre2en#y of fi%e ti0es as $i3$ as t$e "ine fre2en#y!

SERIES ACTI9E ILTERS =4 insertin a series 5cti*e Filter +etween the 5C source and the load where the harmonic source is e7istin we can force the source current to +ecome sinusoidal The techniue is +ased on a principle of harmonic isolation +4 controllin the output *oltae of the series acti*e filter

Eui*alent Circuit

- The series acti*e filter e7hi+its hih impedance to harmonic current and conseuentl4 +loc3s harmonic current flow from the load to the source

C

IS

= Rut:ut !