Simplified Convertor for Traction (2)

7/24/2019 Simplified Convertor for Traction (2)

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Electrified railway system as a special power user,

has the following features- Load current is non linear,- non-sinusoidal- no symmetry,

- use of uncontrolled rectification to feed thetraction load contributes to the total unbalanceseen from the three phase supply

- produce reactive power,

- High level harmonics and- negative sequence current.

Introduction


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Out of the above, presence of highdegree of harmonic current ontraction load is more important.

A simple and cost e ective andpractical method is suggested here forreducing current harmonics

two no of passive lters-ie single

tuned and high pass lter- issuggested here

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Electric Traction !stem"escriptionElectric traction suppl! for #$%&, $'()

single-phase A* suppl! is fed from thestate utilities.

The traction sub-stations generall!spaced +'- ' % apart and the! ta%e

power from an! two phases of the powerutilit! transmission lines. The! have an input voltage of##' /00 /+# //' %&, which is step downto single phase #$%& using tractiontransformers


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T!p ca ee ng arrangementof #$%& electri ed railwa!

s!stem

!


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IN C O M I N G E H V S U P P L Y( 2 2 0 / 1 3 2 / 1 1 0 / 1 6 6 k v

D PI S O L A T O R

C I R C U IT B R E A K E RL I G H T N I N GA R R E S T E R

T R A C T I O NT R A N S F O R M E R

2 k v L IG H T N I N GA R R E S T E R

2 ! k v C T

2 ! k v C IR C U I T B R E A K E R

2 ! k v S P IS O L A T O R1 0 0 k v " # 2 ! k v /2 0 V L T S U P P L Y

T R A N S F O R M E R2 ! k v S P IS O L A T O R

2 ! k v C T

2 ! k v F E E D E R C I R C U IT B R E A K E R

2 ! k v S P IS O L A T O R

2 ! k v B U S C O U P L E RI N T E R R U P T O R( N O R M A L O P E N $

C T

T O B U R I E D R A I L %N E A R E S T R U N N I N GT R A C K2 ! K V S P IS O L A T O R

N O R M A L L Y C L O S E D

2 ! k vC T

2 ! K V / 1 1 0 V P T( P R O T E C T I O N $

2 ! k v I N T E R R U P T O R2 ! k v S P IS O L A T O R

2 ! k v P T

2 K V L A S T A T IO N T Y P E &H E A V Y D U T Y

S U B ' S E C T O RS E C T I O N IN G A N D P A R A L L E L I N G P O S T ( ) $ S P

S U B ' S E C T O RS U B ' S E C T O RB R I D G I N G

I N T E R R U P T O R

S U B S E C T I O N I N G %P A R A L L E L I N G S T A T IO N ( S S P $

T Y P IC A L S C H E M A T I C O F T R A C T I O N P O * E R S U P P L Y F E E D I N G A R R A N G

S E C T O R


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1loc% "iagram of Electric

locomotive

"


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25 kv Conventional OHE system

$%%

2! &'(HE

)* Loco


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2ssues due to (armonics in

Electric traction

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(armonic Anal!sis

Load current measured at the feeder for one day


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'oltage measured at the feeder for one day


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*urrent harmonics at the feeder


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$he pea& current is + ) and pea& $H is ++.+/. $he pea& value of 3rd harmonic is / and average value

comes to 3 /. 3rd and "th harmonic frequencies is present along with the

fundamental. )lso a lesser amount of "th and !th harmonic frequencies

are present

presence of these harmonics creates problems in thelocomotive and the traction substation equipment


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"esign of harmonic lter3assive lter comprising capacitor and inductor issuggested to provide at traction substation4 it is simple, cheap and economical its maintenance and operation is eas!

# passive lters are introduced on #$ side of tractionsubstation one is ingle tuned 5ilter and other is (ighpass lter. 2t is connected in parallel with nonlinearload to provide low-impedance paths for speci charmonic fre6uencies thus resulting in absorbing thedominant harmonic currents 7owing out of the load


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single tuned passive 8* lter is

designed for eliminating +rd

harmonicfre6uenc! and a high pass lter isdesigned for cancelling /9 th and otherhigher order harmonics

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8* lter is designed using the followinge6uations: lter ;?here : lter is the net reactance of the lter: lter ; : cap @: 8 ------------------- =#>: cap ; h # : lter ---------------- =+>?here h; tuned harmonic fre6uenc!.

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L* filter connected to traction substation


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simulation current harmonics after introduction of filter


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*O *8B 2O*urrent (armonic issues due to tractionload due to the use of power semiconductorswitches in ac locomotives is reduced b!introducing a single tuned harmonic lter

designed to eliminate the +rd harmonicfre6uenc! and a high pass lter designed toeliminate /9 th harmonic fre6uenc! contents.

The anal!sis of passive ltering was made

in AT8A1- 2 B82 < environment

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REFERENCES 1 iang4heng u, 5aichao *hen, 6%tudy on %ynthesis *ontrol of 7ower 8uality forElectrified 9ailway,: ;or&shop on 7ower Electronics and . 7ilo, S. B. $enna&oon,: 'oltage regulation on 2!&' ac railway systems byusing thyristor switched capacitor, 7roceedings of


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1! 9.5arnes, .$. ;ong, 6 nbalance and harmonic studies for the *hannel $unnelrailway system,:


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Thank you for your attentionThank you for your attention

Simplified Convertor for Traction (2)

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