Series compensation FACTS Unit-4 by Y H M Reddy

FACTS UNIT-4 Series Compensators
Variable Impedance Type Series Compensators- GTO thyristor-controlled Series Capacitor (GSC) – Thyristor Switched Series Capacitor (TSSC) and Thyristor Controlled Series Capacitor (TCSC) - Switching Converter type Series Compensation

1. 1
FLEXIBLEALTERNATING
CURRENTTRANSMISSION
SYSTEMS
.
Presented By :
HARI MADHAVA REDDY. Y (Ph.D)., M.Tech., MISTE., SSI., IAENG
Assistant professor
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

2. 2
Learning Objectives
To learn the basics of power flow control in transmission
lines using FACTS controllers
To explain operation and control of voltage source converter.
To understand compensation methods to improve stability
and reduce power oscillations of a power system.
To learn the method of shunt compensation using static VAR
compensators.
To learn the methods of compensation using series compensators
To explain operation of Unified Power Flow Controller (UPFC).

3. 3
Learning Outcomes
UnderstandpowerflowcontrolintransmissionlinesusingFACTS
controllers.
Explainoperationandcontrolofvoltagesourceconverter.
Analyzecompensationmethodstoimprovestabilityandreduce
poweroscillationsinthetransmissionlines.
ExplainthemethodofshuntcompensationusingstaticVAR
compensators.
Understandthemethodsofcompensationsusingseries
compensators.
ExplainoperationofUnifiedPowerFlowController(UPFC).

4. About
Tolearnthebasicsofpowerflow
controlintransmissionlinesusing
FACTScontrollers
Toexplainoperationandcontrolofvoltage
sourceconverter.
Tounderstandcompensationmethods
toimprovestabilityandreducepower
oscillationsofapowersystem.
Tolearnthemethodofshuntcompensation
usingstaticVARcompensators.
Tolearnthemethodsofcompensation
usingseriescompensators
ToexplainoperationofUnifiedPower
FlowController(UPFC).
COURSE
OBJECTIVES
introduction
lesson1
Lesson
2
Lesson
3
Lesson
4
Lesson
5

5. Lesson
1
Introduction to
FACTS
Lesson
2
Voltage
source and
Current
source
converters
Lesson
3
FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEMS
As per JNTUK
Shunt
Compensators
–I
Lesson
4
Shunt
Compensators
–II
Lesson
5
Series
Compensators
Lesson
6
Combined
Controllers

6. Lesson
1
Introduction to
FACTS
Lesson
2
Objectives of
shunt and
Series
Compensation
Lesson
3
FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEMS
Shunt
Compensators
Lesson
4 Lesson
5
Series
Compensators
Combined
Controllers

7. 1 2
4
Introduction to
FACTS
3
Shunt
Compensator
Series
Compensators
Objectives of
shunt and
Series
Compensation

8. 8
Text Books:
1. “Understanding FACTS” N.G.Hingoraniand L.Guygi, IEEE
Press.IndianEdition is available:––Standard Publications, 2001.
Reference Books:
1.“Flexible ac transmission system (FACTS)” Edited by Yong Hue
Song and Allan T Johns, Institution of Electrical Engineers,
London.
2. Thyristor-based FACTS Controllers for Electrical Transmission
Systems, by R.MohanMathurand Rajiv k.Varma, Wiley

9. 9

10. About
History
introduction
lesson
1
Lesson
2
Lesson
4
IV. Series Compensators
4.1 Variable Impedance Type Series Compensators
4.2. GTO thyristor-controlled Series Capacitor
(GSC)
4.3 Thyristor Switched Series Capacitor (TSSC)
4.4 Thyristor Controlled Series Capacitor (TCSC)
4.5 Switching Converter type Series Compensation
(SSSC).

11. 11
4.0. Methods of Controllable VarGeneration
Seriescapacitivecompensationwasintroduceddecades
agotocancelaportionofthereactivelineimpedanceand
therebyincreasethetransmittablepower.
Subsequently,withintheFACTSinitiative,ithasbeen
demonstratedthatvariableseriescompensationishighly
effectiveinbothcontrollingpowerflowinthelineandin
improvingstability.
Controllableserieslinecompensationisacornerstoneof
FACTStechnology.Itcanbeapplied
toachievefullutilizationoftransmissionassetsby
controllingthepowerflowinthelines
preventingloopflows
withtheuseoffastcontrols,minimizingtheeffectofsystem
disturbances,therebyreducingtraditionalstabilitymargin
requirements.

12. 12
Concept ofSeries Capacitive CompensationConcept of series capacitive compensation
Thebasicideabehindseriescapacitivecompensationisto
decreasetheoveralleffectiveseriestransmissionimpedancefromthe
sendingendtothereceivingend,i.e.,XintheP=(??????
2
/X)sinδ
relationshipcharacterizingthepowertransmissionoverasingleline.
Considerthesimpletwo-machinemodel,withaseriescapacitor
compensatedline,which,forconvenience,isassumedtobecomposedof
twoidenticalsegments.Notethatforthesameendvoltagesthe
magnitudeofthetotalvoltageacrosstheserieslineinductance,
Vx=2Vx/2isincreasedbythemagnitudeoftheoppositevoltage,Vc
developedacrosstheseriescapacitorandthisresultsfromanincreasein
thelinecurrent.

13. 13
Effective transmission impedance with the series capacitive compensation is

14. 14
4.0. Comparison of Shunt and Series Compensation
Therearetwobasicapproaches
Power electronics-based shunt
compensators; TSC, TCR to realize
a variable reactive admittance
Switchingpowerconverter to
realizeacontrollable
synchronous voltage source.
The series compensator isareciprocal ofthe shunt compensator.
Becauseofthisdualitybetweentheshuntandseriescompensators,
manyoftheconcepts,andcircuitandcontrolapproachesofshunt
compensatorsareapplicable,withacomplementaryviewinseries
compensators.

15. 15
S.
No
.
PARAMETER ShuntCompensation SeriesCompensation
1functionally a
controlled
reactive current
source
voltagesource
2connectedin parallelwiththe
transmissionline
series withthe
transmissionline
3tocontrol
Its(Tr.Line)voltageIts(Tr.Line)current.
4reciprocity
admittance
avariablereactive
impedance
5basic reference
parameter(or)the
operation ofthe
compensatorisviewed
fromtheperspective
of
transmissionvoltagelinecurrent

16. About
History
introduction
lesson
1
Lesson 2 Lesson
4
IV. Series Compensators
4.1 Variable Impedance Type Series Compensators
4.2. GTO thyristor-controlled Series Capacitor
(GSC)
4.3 Thyristor Switched Series Capacitor (TSSC)
4.4 Thyristor Controlled Series Capacitor (TCSC)
4.5 Switching Converter type Series Compensation
(SSSC).

17. 17
variableimpedancetypeseriescompensatorsarecomposedof
Thyristor-switched/controlled-capacitors(GCSC)TSSCor
Thyristor-controlledreactorswithfixedcapacitors(TCSC).
4.1. VARIABLE IMPEDANCE TYPE SERIES
COMPENSATORS
4.2. GTOThyristor-Controlled SeriesCapacitor(GCSC)
Construction:AnelementaryGTOThyristor-ControlledSeries
Capacitor,proposedbyKaradywithothersin1992,isshown.It
consistsofafixedcapacitorinparallelwithaGTOthyristor(or
equivalent)valve(orswitch)thathasthecapabilitytoturnonand
offuponcommand.
TheobjectiveoftheGCSCschemeshownistocontroltheac
voltageVcacrossthecapacitoratagivenlinecurrenti.

18. 18

19. 19
Operation: whentheGTOvalve,SW,isclosed,thevoltage acrossthe
capacitoriszero, when the valve is open, it is maximum.
Forcontrollingthecapacitorvoltage,theclosingandopeningof
thevalveiscarriedoutineachhalf-cycleinsynchronismwith
theacsystemfrequency.
TheGTOvalveisstipulatedtocloseautomatically(through
appropriatecontrolaction)wheneverthecapacitorvoltagecrosses
zero.(RecallthatthethyristorvalveoftheTCRopensautomatically
wheneverthecurrentcrosseszero).
However,theturn-offinstantofthevalveineachhalf-cycleis
controlledbya(turn-off)delayangleγ(0≤γ≤π/2),withrespectto
thepeakofthelinecurrent.
wherethelinecurrenti,andthecapacitorvoltageVC(γ)are
shownatγ=0(valveopen)andatanarbitraryturn-off
delayangleγforapositiveandanegativehalf-cycle.

20. 20

21. 21
Whenthevalveswisopenedatthecrestofthe(constant)line
current(γ=0),theresultantcapacitorvoltageVcwillbethe
sameasthatobtainedinsteadystatewithapermanently
openswitch.Whentheopeningofthevalveisdelayedbythe
angleγwithrespecttothecrestofthelinecurrent,the
capacitorvoltagecanbeexpressedwithadefinedline
current,asfollows
Sincethevalveopensatγand stipulatedtocloseatthefirstvoltage
zero,isvalid for theintervalγ≤ ωt≤ π–γ.
Forsubsequentpositivehalf-cycleintervalsthesameexpression
remainsvalid.Forsubsequentnegativehalf-cycleintervals,thesignof
thetermsbecomesopposite.

22. 22
Itisevidentthatthemagnitudeofthecapacitorvoltagecanbe
variedcontinuouslybythismethodofturn-offdelayangle
controlfrommaximum(γ=0)tozero(γ=π/2),wherethe
capacitorvoltageVc(γ),togetherwithitsfundamentalcomponent
VCF(y),areshownat,varioustum-offdelayangles.However,that
theadjustmentofthecapacitorvoltage,similartothe
adjustmentoftheTCRcurrent,isdiscreteandcantakeplace
onlyonceineachhalf-cycle.
whereIistheamplitudeofthelinecurrent,Cisthe
capacitanceoftheGTOthyristorcontrolledcapacitor,andωis
theangularfrequencyoftheacsystem.

23. 23
OnthebasisoftheGCSC,
varyingthefundamental
capacitorvoltageatafixed
linecurrent,couldbe
consideredasavariable
capacitive impedance.
Indeed, an effective
capacitiveimpedancecanbe
foundforagivenvalueof
angleγOr,inotherwords,
an effectivecapacitive
impedance,Xc,asafunctionof
γ,fortheGCSCcanbedefined.

24. 24
Attainable V-1 (compensating voltage vs.linecurrent) characteristics of the GCSC when operated in voltage control (a1) and
reactance control (b1) modes, and the associated loss vs. line current characteristics (a2 and b2, respectively).
InapracticalapplicationtheGCSCcanbeoperatedeithertocontrol
thecompensatingvoltage,VCF(γ),orthecompensatingreactance,
Xc(γ).
Inthevoltagecompensationmode,theGCSCistomaintaintherated
compensatingvoltageinfaceofdecreasinglinecurrentovera
definedintervalImin≤I≤Imax(Fig.a1).

25. 25
Inthiscompensation modethe
capacitivereactanceXcisselectedso
astoproducetheratedcompensating
voltagewithI=Imin,i.e.,Vcmax=Xc
Imin.Ascurrentlminisincreased
towardImax,theturn-offdelayangle
γisincreasedtoreducetheduration
ofthecapacitorinjectionandthereby
maintainthecompensatingvoltage
withincreasinglinecurrent.
Theloss,aspercentoftherated
varoutput,versuslinecurrent
characteristicoftheGCSCoperated
inthevoltagecompensationmodeis
shown,forzerovoltageinjection[the
capacitorisbypassedbytheGTO
valvetoyieldVcF(γ)=O]andfor
maximumratedvoltageinjection
[VCF(γ)=Vcmax].

26. 26
Intheimpedancecompensation
mode,theGCSCistomaintain
themaximumratedcompensating
reactanceatanylinecurrentup
totheratedmaximumshownin
fig.Inthiscompensationmode
thecapacitiveimpedanceis
chosensoastoprovidethe
maximumseriescompensation
atratedcurrent,
that the GCSC can varyinthe range by controlling
the effective capacitor voltage
Thelossversuslinecurrent
characteristicoftheGCSCfor
thisoperatingmodeisshown
forzerotonmaxcompensation
impedance

27. 27
Theimpedanceandvoltagecompensatingmodesare,ofcourse,
interchangeablebycontrolactionwithintheratinglimitationof
theseriescapacitorcontrolled.
Theturn-offdelayanglecontroloftheGCSC,justliketheturn-on
delayanglecontroloftheTCR,generatesharmonics.Foridentical
positiveandnegativevoltagehalf-cycles,onlyoddharmonicsare
generated.Theamplitudesoftheseareafunctionofangleγand

28. 28
Basic operating control scheme for GCSC:
Thefunctionoftheoperatingor"internal"controlofthe
variableimpedancetypecompensatorsistoprovide
appropriategatedriveforthethyristorvalvetoproducethe
compensatingvoltageorimpedancedefinedbyareference.
Theinternalcontroloperatesthepowercircuitoftheseries
compensator,enablingittofunctioninaself-sufficientmannerasa
variablereactiveimpedance.Thus,thepowercircuitoftheseries
compensatortogetherwiththeinternalcontrolcanbeviewedasa
"blackbox"impedanceamplifier,theoutputofwhichcanbevaried
fromtheinputwithalowpowerreferencesignal.

29. 29
Thereferencetotheinternalcontrolisprovidedbythe"external"or
systemcontrol,whosefunctionitistooperatethecontrollablereactive
impedancesoastoaccomplishspecifiedcompensationobjectivesof
thetransmissionline.Thustheexternalcontrolreceivesaline
impedance,current,power,oranglereferenceand,withinmeasured
systemvariables,derivestheoperatingreferencefortheinternal
control.
Structurallytheinternalcontrolsforthethreevariableimpedance
typecompensators(GCSC,TCSC,TSSC)couldbesimilar.Succinctly,
theirfunctionissimplytodefinetheconductionand/orthe
blockingintervalsofthevalveinrelationtothefundamental
(powerfrequency)componentofthelinecurrent.
Thisrequirestheexecutionofthreebasicfunctions:
synchronization to the linecurrent,
turn-on orturn-offdelayangle computation,and
gate (firing)signal generation.

30. 30
Functional internal control scheme for the GCSC

31. 31
Waveforms illustrating the basic operating principles of GCSC

32. 32
Thethirdfunctionisthedeterminationoftheinstantofvalve
turn-onwhenthecapacitorvoltagebecomeszero.(This
functionmayalsoincludethemaintenanceofaminimumon
timeatvoltagezerocrossingstoensureimmunityto
subsynchronousresonance.)
Thefourthfunctionisthegenerationofsuitableturn-offandturn-
onpulsesfortheGTOvalve.
Thefirstfunctionissynchronoustiming,providedbyaphase-
lockedloopcircuitthatrunsinsynchronismwiththelinecurrent.
Thesecondfunctionisthereactivevoltageorimpedancetotum-
offdelayangle conversion accordingto the relationshiprespectively.

33. About
History
introduction
lesson
1
Lesson
2
Lesson
4
IV. Series Compensators
4.1 Variable Impedance Type Series Compensators
4.2. GTO thyristor-controlled Series Capacitor
(GSC)
4.3 Thyristor Switched Series Capacitor (TSSC)
4.4 Thyristor Controlled Series Capacitor (TCSC)
4.5 Switching Converter type Series Compensation
(SSSC).

34. 34
4.3. Thyristor-Switched Series Capacitor (TSSC)
Basic Thyristor-Switched Series Capacitor scheme.
Construction:Thebasiccircuitarrangementofthethyristor-switched
seriescapacitorisshown.Itconsistsofanumberofcapacitors,each
shuntedbyanappropriatelyratedbypassvalvecomposedofastringof
reverseparallelconnectedthyristors,inseries.
Itsoperationisdifferentduetotheimposedswitchingrestrictions
oftheconventionalthyristorvalve.Theoperatingprincipleofthe
TSSCisstraightforward:thedegreeofseriescompensationis
controlledinastep-likemannerbyincreasingordecreasingthe
numberofseriescapacitorsinserted.

35. 35
Acapacitor isinserted byturning off,and itis bypassed byturning
on the corresponding thyristor valve.
Athyristorvalvecommutates"naturallywhenthecurrentcrosses
zero.
Capacitorcanbeinsertedintothelinebythethyristorvalveonlyat
thezerocrossingsofthelinecurrent(I=0).Atthatinstant,fullhalf-
cycleofthelinecurrentwillchargethecapacitorfromzeroto
maximum&oppositepolarityhalf-cycleofthelinecurrentwill
dischargeitfromthismaximumtozero.

36. 36
Thecapacitorinsertionatlinecurrentzero,necessitatedby
theswitchinglimitationofthethyristorvalve,resultsinadcoffset
voltagewhichisequaltotheamplitudeoftheaccapacitor
voltage(Vc).
Inordertominimizetheinitialsurgecurrentinthevalve,and
thecorrespondingcircuittransient,thethyristorvalveshouldbe
turnedonforbypassonlywhenthecapacitorvoltageiszero.(Vc=0).
Toprevailingdcoffset,thisrequirementcancauseadelayof
uptoonefullcycle,whichwouldsetthetheoreticallimitforthe
attainableresponsetimeoftheTSSC.
TSSCcancontrolthedegreeofseriescompensationby
eitherinsertingorbypassingseriescapacitorsbutitcannotchange
thenaturalcharacteristicofseriescompensationline.

37. 37
HighdegreeofTSSCcompensationcouldcausesub-synchronous
resonanceasanordinarycapacitor.
TheTSSCswitchingcouldbemodulatedtocounteract
subsynchronousoscillationsbylongswitchingdelaysencountered.
Drawbacks:
ThepureTSSCschemenotbeusedincriticalapplications
whereahighdegreeofcompensationisrequiredandthedangerof
subsynchronousresonanceispresent.
Application:
TheTSSCcouldbeappliedforpowerflowcontrolandfor
dampingpoweroscillationwheretherequiredspeedofresponseis
moderate.

38. 38
TSSCCharacteristics: Voltage Compensation Mode
Impedance Compensation Mode
i.Voltage Compensation Mode:
a. V-I Characteristics:
Four Series Capacitors are connected
reactanceofthecapacitorbanks(Xc)ischosensoastoproduce,
ontheaverage,theratedcompensatingvoltage
Line current will vary b/w
ThecurrentIminisincreased
towardImax thecapacitor
banks areprogressively
bypassedbytherelatedthyristor
valvestoreducetheoverall
capacitivereactanceinastep-
likemanner andthereby
maintainthecompensating
voltagewithincreasingline
current.

39. 39
b. %loss vsLine current Characteristics:
Forzerovoltageinjection(all
capacitorsarebypassed)
and
formaintainingmaximum
rated voltageinjection
(capacitorsareprogressively
bypassed).

40. 40
In the impedance compensation mode, the TSSC is applied
to maintain the maximum rated compensating reactance atanyline
current uptotherated maximum.
*Capacitiveimpedance(Xc)is
chosensoastoprovidethe
maximumseriescompensationat
ratedcurrent4Xc=
??????
????????????????????????
????????????????????????
.TSSC
canvaryinastep-likemannerby
bypassingoneormorecapacitor
banks.
a. V-I Characteristics:
b. %loss vsLine current Characteristics:
forzero compensatingimpedance (all
capacitor banks are bypassed by the
thyristor valves) and for maximum
compensating impedance (all thyristor
valves are offand allcapacitors are
inserted).

41. 41
Limitations:
TheTSSCmayalsohavetransientratings,usuallydefinedasa
functionoftime.
Solution:DefinedratingstheTSSCwouldbeprotectedagainst
excessivecurrentandvoltagesurgeseitherbyexternalprotection
acrossthecapacitorandtheparallelvalveor,withsufficient
rating,bythevalveitselfinbypassoperation.
Advantages:
•Rapid,continuouscontrolofthetransmission-lineseries-
compensationlevel,allowingfordynamiccontrolofpowerflowin
selectedtransmissionlines.
•Noharmonicsgeneration,unlikeThyristorControlledReactors
(TCR).
•Improvedcontrolandflexibility
•Enhancedsteady-stateanddynamicoperationofpowersystems
•Abilitytocontrolthedegreeofseriescompensation

42. About
History
introduction
lesson
1
Lesson
2
Lesson
4
IV. Series Compensators
4.1 Variable Impedance Type Series Compensators
4.2. GTO thyristor-controlled Series Capacitor
(GSC)
4.3 Thyristor Switched Series Capacitor (TSSC)
4.4 Thyristor Controlled Series Capacitor (TCSC)
4.5 Switching Converter type Series Compensation
(SSSC).

43. 43
The Thyristor Switched Series Compensator (TCSC) has several applications in
power systems, including:
•Power flow control: TCSC can improve power system performance by
controlling power flow.
•System performance enhancements: TCSC can be used for various power
system performance enhancements, such as improving system stability and
transfer capability.
•Dynamic power flow control: TCSC is a controllable FACTS device used for
dynamic power flow control through variation of the reactance of a
transmission tie line.
•Reactive power compensation: TCSC can be used for dynamic reactive
power compensation applications.
•Increasing load carrying capacity: Thyristor switched and controlled series
capacitor systems were developed to enable increased load carrying capacity of
existing high-voltage transmission lines.
•Radial distribution circuits: TCSCs can be suitably rated for radial
distribution circuits.
•Rapid, continuous control of transmission-line impedance: Use of thyristor
control in series capacitors offers rapid, continuous control of the transmission-
line impedance.

44. 44
4.4. Thyristor-Controlled Series Capacitor (TCSC)
Construction:Proposedin19δ6byVithayathilwithothersasa
methodof"rapidadjustmentofnetworkimpedance,"Itconsistsof
theseriescompensatingcapacitorshuntedbyaThyristor-Controlled
Reactor.
The Z of reactor( ??????
??????)<
????????????&#3627408477;??????????????????&#3627408481;&#3627408476;&#3627408479;(??????
??????).
Operates as ON/OFF
like TSSC.
Operation:
Thebasicideabehind theTCSC scheme istoprovide acontinuously
variable capacitor bymeans ofpartially canceling the effective
compensating capacitance by the TCR.
The TCR at the fundamental system frequency is a continuously
variable reactive impedance, controllable by delay angle α

45. 45
Thesteady-stateimpedanceoftheTCSCisthatofaparallelLC
circuit,consistingofafixedcapacitiveimpedance,Xc,anda
variableinductiveimpedance,??????
??????(α),
where, from TCR
(series)
(shunt)
XL=ωL,andαisthedelayanglemeasuredfromthecrestof
thecapacitorvoltage(or,equivalently,thezerocrossingofthe
linecurrent).
https://scijournals.onlinelibrary.wiley.com/doi/full/10.1002/ese3.1628
Kis the compensation coefficient.

46. 46https://pandapower.readthedocs.io/en/latest/elements/tcsc.html
https://www.slideshare.net/slideshow/tcsc-124136067/124136067
The TCSC thus presents atunable parallel LC
circuit tothe linecurrent that is substantially a
constant alternating current source.
The degree of series capacitive compensation:
Theimpedanceofthecontrolledreactor,??????
??????(α),isvariedfromits
maximum(infinity)towarditsminimum(ωL),theTCSCincreases
itsminimumcapacitiveimpedance??????
&#3627408455;??????&#3627408454;??????,&#3627408474;??????&#3627408475;=??????
??????=1/ωC.until
parallelresonanceat??????
??????=??????
??????(α),??????
&#3627408455;??????&#3627408454;??????,&#3627408474;????????????theoreticallybecomes
infinite.
Thedegreeofseriesinductivecompensation:
Decreasing??????
??????(α)further,theimpedanceoftheTCSC,??????
&#3627408455;??????&#3627408454;??????(α)
becomesinductive,reachingitsminimumvalueof??????
????????????
??????/??????
??????−??????
??????at
α=0.(wherethecapacitorisineffectbypassedbytheTCR).
TCSCarrangementinwhich,
theZofreactor(??????
??????)<(&#3627408480;&#3627408474;??????&#3627408473;&#3627408473;??????&#3627408479;&#3627408481;ℎ??????&#3627408475;)????????????&#3627408477;??????????????????&#3627408481;&#3627408476;&#3627408479;(??????
??????).

47. 47
The TCSC has two operating ranges around itsinternal circuit
resonance:
i.α
??????&#3627408473;??????&#3627408474;≤ α≤ᴨ/2 range, ??????
&#3627408455;??????&#3627408454;??????(α) is capacitive
ii.0 ≤ α≤α
??????&#3627408473;??????&#3627408474;range, ??????
&#3627408455;??????&#3627408454;??????(α) is inductive.
The impedance vs. delay angle αcharacteristic of the TCSC.

48. 48

49. 49
MODES OF TCSCOPERATION:
BYPASSED-THYRISTOR MODE
BLOCKED-THYRISTOR MODE
PARTIALLYCONDUCTINGTHYRISTOR,OR VERNIER, MODE

50. 50
Thecompensating voltage versuslinecurrent (V-I)characteristic of
abasicTCSC : voltage compensation mode
Inthecapacitive region the
minimum delay angle,α
??????&#3627408473;??????&#3627408474;,
setsthelimitforthemaximum
compensatingvoltageuptoa
valueoflinecurrent(??????
&#3627408474;??????&#3627408475;)at
whichthemaximum rated
voltage,??????
??????&#3627408474;????????????
,constrainsthe
operationuntiltherated
maximum current,Imaxis
reached.
Intheinductiveregion,themaximumdelayangle,α
??????&#3627408473;??????&#3627408474;limitsthe
voltageatlowlinecurrentsandthemaximumratedthyristor
currentathighlinecurrents.
(i) V-I Characteristics

51. 51
(ii) The loss,asapercent ofthe rated varoutput, versus linecurrent
forvoltage compensation mode
Inthe capacitive operating
region isshowninFigure (a2) for
maximum andminimum
compensating voltage, aswell as
forbypass operation (thyristor
valveisfullyon).
The lossesare almost entirely due totheTCR, which include the
conduction andswitching losses ofthe thyristor valve andthe??????
2
??????
lossesofthe reactor.

52. 52
In the impedance compensation mode
TheTCSCisappliedto
maintainthemaximumrated
compensatingreactanceatany
linecurrentuptotherated
maximum.
Forthisoperatingmodethe
TCSCcapacitorandthyristor-
controlledreactorarechosen
sothatatα
??????&#3627408473;??????&#3627408474;themaximum
capacitivereactancecanbe
maintainedatandbelowthe
maximumratedlinecurrent
(i) V-I Characteristics
(ii) apercent ofthe rated var
output, versus linecurrent
Thelossversuslinecurrent
characteristicforthisoperating
modeisshowninFigure(b2)
formaximum andminimum
capacitive compensating
reactances.

53. 53
Basic operating control scheme for TCSC:
The internal control operating the powercircuitoftheTCSCisto
ensure immunity tosubsynchronousresonance
(i)AfunctionalinternalcontrolschemefortheTCSC
basedonthesynchronizationtothefundamental
componentofthelinecurrent.

54. 54
Twobasiccontrol philosophies
(i)Oneistooperatethe
basicphaselocked-loop
(PLL)fromthefundamental
component oftheline
current.
Toprovide substantial
filteringtoremovethe
subsynchronouscomponents
fromthelinecurrentand,at
thesametime,maintain
correctphaserelationshipfor
propersynchronization.
Thesecondapproachalso
employs a PLL,
synchronizedtotheline
current,forthegeneration
ofthebasictimingreference.
Theactualzerocrossingofthe
Vcisestimatedfromthe
prevailingcapacitorvoltageand
linecurrentbyanangle
correctioncircuit.Thedelay
angleisthendeterminedfrom
thedesiredangleandthe
estimatedcorrectionangleso
astomaketheTCRconduction
symmetricalwithrespecttothe
expectedzerocrossing

55. 55
AfunctionalinternalcontrolschemefortheTCSCbasedonthe
predictionofthecapacitorvoltagezerocrossings.
https://www.scribd.com/document/409911767/FACTS-NOTES

56. 56
4.5 Switching Converter type Series Compensation (SSSC).
https://www.sanfoundry.com/facts-questions-answers-switching-converter-type-series-
compensators/#google_vignette
Avoltage-sourcedconverterwithits
internalcontrolcanbeconsidereda
synchronousvoltagesource(SVS)
analogoustoanidealelectromagnetic
generator:itcanproduceasetof
(three)alternating,substantially
sinusoidalvoltagesatthedesired
fundamentalfrequencywith
controllableamplitudeandphase
angle;generate,orabsorb,reactive
power;andexchangereal(active)
powerwiththeacsystemwhenitsdc
terminalsareconnectedtoasuitable
electricdcenergysourceorstorage.A
functionalrepresentationoftheSVSis
showninFigure

57. 57
ReferencesQreforPref(orotherrelatedparameterssuchasthe
desiredcompensatingreactiveimpedanceXrefandresistanceRref)
definetheamplitudeVandphaseangleΦofthegeneratedoutput
voltagenecessarytoexchangethedesiredreactiveandactivepower
attheacoutput.
IftheSVSisoperatedstrictlyforreactivepowerexchange,Pref(or
Rref)issettozero.
Thefunctionoftheseriescapacitorissimplytoproducean
appropriatevoltageatthefundamentalacsystemfrequencyin
quadraturewiththetransmissionlinecurrentinordertoincreasethe
voltageacrosstheinductivelineimpedance,andtherebyincreasethe
linecurrentandthetransmittedpower.

58. 58
TheStaticSynchronousSeriesCompensator(SSSC)
Basictwo-machinesystemwithaseriescapacitorcompensatedlineand
associatedphasordiagram.
ThebasicoperatingprinciplesoftheSSSCcanbeexplainedwith
referencetotheconventionalseriescapacitivecompensation.
Thephasordiagramclearlyshowsthatatagivenlinecurrentthe
voltageacrosstheseriescapacitorforcestheoppositepolarityvoltage
acrosstheserieslinereactancetoincreasebythemagnitudeofthe
capacitorvoltage.
Thus,theseriescapacitivecompensationworksbyincreasingthe
voltageacrosstheimpedanceofthegivenphysicalline,whichinturn
increasesthecorrespondinglinecurrentandthetransmittedpower.

59. 59
Whileitmaybeconvenienttoconsiderseriescapacitive
compensationasameansofreducingthelineimpedance,itisreallya
meansofincreasingthevoltageacrossthegivenimpedanceofthe
physicalline.
Itfollowsthereforethatthesamesteady-statepowertransmission
canbeestablishediftheseriescompensationisprovidedbya
synchronousacvoltagesource,whoseoutputpreciselymatchesthe
voltageoftheseriescapacitor,i.e.,
Vcis the injected compensating voltage phasor, I is the line current, Xcis
the reactance of the series capacitor, X is the linereactance,
is the degree ofseriescompensation,
Incontrasttotherealseriescapacitor,theSVSisabletomaintaina
constantcompensatingvoltageinthepresenceofvariableline
current,orcontroltheamplitudeoftheinjectedcompensating
voltageindependentoftheamplitudeofthelinecurrent.

60. 60
Fornormalcapacitivecompensation,theoutputvoltagelagsthe
linecurrentby90degrees.ForSVS,theoutputvoltagecanbereversed
bysimplecontrolactiontomakeitleadorlagthelinecurrentby90
degrees
Inthiscase,theinjectedvoltagedecreasesthevoltageacrossthe
inductivelineimpedanceandthustheseriescompensationhasthesame
effectasifthereactivelineimpedancewasincreased.Withtheabove
observations,ageneralizedexpressionfortheinjectedvoltage,Vqcan
simplybewritten:
where
= magnitude of the
injected compensating
voltage
=chosen control parameter

61. 61
Transmitted PowerVersusTransmission Angle
Characteristic

62. 62
ControlRangeandVARating

63. 63
Reference links
https://www.scribd.com/document/409911767/FACTS-NOTES
https://www.sanfoundry.com/facts-questions-answers-switching-converter-type-series-
compensators/#google_vignette
https://pandapower.readthedocs.io/en/latest/elements/tcsc.html
https://www.slideshare.net/slideshow/tcsc-124136067/124136067
https://scijournals.onlinelibrary.wiley.com/doi/full/10.1002/ese3.1628

64. 64
Q.No
Question M CO BTPI’S
1
a.WithcircuitdiagramexplainV-I&percentagelossvslinecurrent
characteristicsforvoltagecompensationmodeandimpedance
compensationmodeofTSSC(ThyristorSwitchedSeriesCapacitor).
8C413.4L2
1.4.1
3.1.6
b.Withcircuitdiagramandwaveforms,explaintheoperationof
GCSC.DrawtheirV-I&percentagelossvslinecurrent
characteristics.
8C413.4L3
1.4.1
3.1.6
2
a.ExplainthefunctionalcontrolschemefortheGCSC. 8C413.4L1
1.4.1
3.1.6
b.Withcircuitdiagramandwaveforms,explaintheoperationof
TCSC.
8C413.4L2
1.4.1
3.1.6
3
Withcircuitdiagramandwaveforms,explaintheoperationof
switchingconvertertypeseriescompensator(SSSC).
16C413.4L3
1.4.1
3.1.6
4
a.Withcircuitdiagramandwaveforms,explaintheoperationof
variableImpedancetypeseriescompensator.
8C413.4L2
1.4.1
3.1.6
b.ExplainthefunctionalcontrolschemefortheTCSC 8C413.4L2
1.4.1
3.1.6
Question Bank

65. 65
7%
60%
33%
Bloom's Level wise Marks Distribution
L1
L2
L3

66. 66
COURSE OUTCOMES
S.NO DESCRIPTION Taxonomy Level
CO413.1
Explainthebasicsofpowerflowcontrolin
transmissionlinesusingFACTScontrollers
Understanding (TL-2)
& Analyzing (TL-4)
CO413.2
DistinguishfunctionalRequirementsofshuntand
seriescompensators.
Understanding (TL-2)
& Analyzing (TL-4)
CO413.3
Describesthemethodofshuntcompensationusing
staticVARcompensators.
Remembering (TL-1)
& Applying (TL-3)
CO413.4
Explainthemethodsofcompensationusingseries
compensators.
Understanding (TL-2)
& Analyzing (TL-4)
CO413.5
Explainthemethodsofcompensationusing
combinedcompensators
Understanding (TL-2)
& Analyzing (TL-4)

67. 67
CO-PO MAPPING
S.NoPO1PO2PO3PO4PO5PO6PO7PO8PO9PO10PO11PO12
CO413.1 3 2 1 1 ---------- -- -- --
CO413.2 3 1 2 1 ---------- -- -- --
CO413.3 3 1 2 2 1 -------- -- 1 1
CO413.4 3 1 2 2 1 -------- -- 1 1
CO413.5 2 1 3 1 1 -------- -- 1 1
CO-PSO Mapping
PSO1 PSO2 PSO3
CO413.1 1 3 -
CO413.2 - 3 -
CO413.3 2 3 1
CO413.4 2 3 1
CO413.5 2 3 1

68. 68
Three Learning Domain and Action Verbs
Cognitive Domain
(PO1-PO8, PO11), Head
(Writen)
Psychomotor
Domain(PO4-PO5),
Hand (practical)
Affective Domain
(PO6-PO12), Heart (Feelings)
C1Remembering
Define, What, List, Sketch,
Write
P1Imitate
Copy, Follow,
Repeat
A1 Receive
Accept, Attend, Recognize
C2Understanding
Explain, Illustrate, Discuss
P2Manipulation
execute, implement,
perform
A2Respond
Obey, Respond, Comply
C3Applying
Apply, Solve, Show,
Determine, Compute
P3Precision
show, Demonstrate
A3Value
Accept, Defend, Devote,
Pursue, Seek
C4Analyzing
Analyze, Illustrate, Test,
Inspect
P4Articulation
Develop, Construct,
Solve, Adapt,
A4Organize
Display, Order, Organize
C5Evaluating
Justify, Compare,
Differentiate, Summarize
P5Naturalization
Design, Invent,
Specify
A5Internalize
Internalize, Verify
C6Creating/ Designing
Design, Create, Modify,
Build, Solve

69. 25-08-2024 HARI MADHAVA REDDY .Y
(Ph.D)
69

70. 25-08-2024 HARI MADHAVA REDDY .Y
(Ph.D)
70

71. 71
చాలామందిశ్రమపడుతూనేఅంటారు.. కానీఇతరులకువచ్చినట్లు గావాళ్ళకి
ఫలితాలులభంచవు.వాళ్ళళతెలుసుకోవలసినదిఏమిటంటే..
శ్రమ+ సరైనపనిముట్లు= మంచ్చఫలితాలు
శ్రమ+ తప్పుడుపనిముట్లు= ఫలితంశూనయం.
సరైనసాధనాలకోసంఎపుటికప్పుడుజ్ఞా నసముపార్జనచేసుత ండాలి. విజ్ఞా లదగ్గర్
తర్ఫీదుపందాలి.

72. 25-08-2024 HARI MADHAVA REDDY .Y
(Ph.D)
72

73. 73
https://telugu.hindustantimes.com/lifestyle/check-5-easy-ways-to-
improve-your-memory-naturally-121674631683333.html

74. 74
https://learningcenter.unc.edu/tips-and-tools/enhancing-your-memory/
https://www.usa.edu/blog/science-backed-memory-tips/
https://www.clearias.com/memory-techniques/
https://opentextbc.ca/studentsuccess/chapter/memory-techniques/