Post on 04-Oct-2015
description
11/3/2014
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Topic4Topic4INDUSTRIALINDUSTRIALPOWERQUALITYPOWERQUALITYBEF44903BEF44903
By:Engr.Dr.Kok BoonChing (JEK2013)
1
BEF44903 IndustrialPowerSystems Topic4
OutlinesOutlines4.1MotorStartingStudies
2
4.2ApplicationofIndustrialPowerFactorCorrection
4.3HarmonicsTreatmentinIndustrialPowerSystems
4 4 V lt S A l i4.4VoltageSagAnalysis
4.5FlickerAnalysis
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BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesDirectonDirectonlinestartinglinestarting Whenitisswitchedon,the
motor behaves like a
3
motorbehaveslikeatransformerwithitssecondary,formedbytheverylowresistancerotorcage,inshortcircuit.
Thereisahighinducedcurrentintherotorwhichresultsinacurrentpeakinthemainssupplypp y
Currentonstarting=5to8ratedCurrent
Torqueonstarting(ST)=0.5to1.5ratedtorque(RT)
BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesStarStardeltastartingdeltastarting Theprincipleistostartthe
motor by connecting the star
4
motorbyconnectingthestarwindingsatmainsvoltage,whichdividesthemotorsratedstarvoltageby3.
Thestartingcurrentpeak(SC)isdividedby3,SC=1.5to2.6RC(RCratedCurrent).
As the starting torque (ST) isAsthestartingtorque(ST)isproportionaltothesquareofthesupplyvoltage,itisalsodividedby3:ST=0.2to0.5RT(RTRatedTorque)
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BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesResistancestatorstartingResistancestatorstarting Themotorstartsatreduced
voltage because resistors are
5
voltagebecauseresistorsareinsertedinserieswiththewindings.
Whenthespeedstabilises,theresistorsareeliminatedandthemotorisconnecteddirectlytothemains.Thisprocessisusuallycontrolledp ybyatimer.
Thestartingcurrentandtorquevaluesaregenerally:SC=4.5RCST=0.75RT
BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesAutotransformerstartingAutotransformerstarting Inthefirstplace,the
autotransformerisstar
6
connected,thenthemotorisconnectedtothemainsviapartoftheautotransformerwindings.
Thestarconnectionisopenedbeforegoingontofullvoltage.Thisoperationtakesplacewhenthespeedbalancesoutattheendofthefirststep.
The piece of autotransformerThepieceofautotransformerwindinginserieswiththemotorisshortcircuitedandtheautotransformerisswitchedoff.
Thevaluesobtainedare:SC=1.7to4RCST=0.5to0.85RT
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BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesSlipringmotorstartingSlipringmotorstarting Aslipringmotorcannotbe
started direct on line with its
7
starteddirectonlinewithitsrotorwindingsshortcircuited,otherwiseitwouldcauseunacceptablecurrentpeaks.
Resistorsmustthereforebeinsertedintherotorcircuitandthengraduallyshortcircuited.
The current absorbed is moreThecurrentabsorbedismoreorlessproportionaltothetorquesupplied.Forexample,forastartingtorqueequalto2RT,thecurrentpeakisabout2RC.
BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesSoftstarterstartingSoftstarterstarting Thisisaneffectivestarting
system for starting and
8
systemforstartingandstoppingamotorsmoothly.
Controlbycurrentlimitationsetsamaximumcurrent(3to4xRC)duringthestartingstageandlowerstorqueperformance.Thiscontrolisespeciallysuitable forturbomachines (centrifugalturbomachines (centrifugalpumps,fans).
Controlbytorqueadjustmentoptimises torqueperformanceinthestartingprocessandlowersmainsinrushcurrent.Thisissuitedtoconstanttorquemachines.
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BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesFrequencyconverterstartingFrequencyconverterstarting Thisisaneffectivestarting
9
systemtousewheneverspeedmustbecontrolledandadjusted.
Itspurposesinclude: startingwithhighinertialoads, startingwithhighloadsonsupplieswithlowshortcircuitcapacity,
optimisation ofelectricityconsumption adapted to the speedconsumptionadaptedtothespeedof"turbomachines".
Itisasolutionprimarilyusedtoadjustmotorspeed,startingbeingasecondarypurpose.
BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudies 10
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BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesVoltagedrop/dip
11
PQduringMotorStarting
InrushcurrentVoltageFlicker
Voltage/CurrentHarmonics
BEF44903 IndustrialPowerSystems Topic4
4.1MotorStartingStudies4.1MotorStartingStudiesEXAMPLE4.1:VoltagedropduringmotorstartingA i d t i l t l t
12
1MVA11kV/415V%Z=5%X/R=5
ZS =(1.55+j1.66)m
PCC
SupplySystemAn industrial customer plans toconnect a new induction motorto the power supply system asshown in the diagram.
Using the permissible level ofvoltage fluctuations as a
M
ZL =(25+j60)m75kW415VPFStart =0.3KSOC =7kVA/kW
PCCvoltage fluctuations as acriterion, decide whether themotor should be installed.For the planned number of 20starts per hour the voltagechange: Kmax = 3%
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC PowerFactorinSinusoidal Situations
R
13
M MotorLoad(Linear)Vsin (t)
R
)sin()()sin()(
101
101
tItitVtv
rmsrms
avgavgtrue IV
PSP
PF
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Forthepurelysinusoidal case,
P
14
22
)cos(22
11
1111
22
IV
IVQP
PPFPF avgdisptrue
wherePFdisp iscommonlyknownasthedisplacementpowerfactor,andwhere(11)isknownasthepower factor angle
)cos(22
11 powerfactorangle.
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC
7.00EffectofPFonPowerLosses
15
2.00
3.00
4.00
5.00
6.00
Power
Losses
(pu) Displacementpowerfactor
greatlyaffectslosses
0.00
1.00
2.00
1.00 0.90 0.80 0.70 0.60 0.50 0.40
P
PF
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC PowerFactorinNonsinusoidal Situations When steady state harmonics are presented the
16
Whensteadystateharmonicsarepresented,thevoltagesandcurrentscanberepresentedbyFourierseriesoftheform,
1
0 )sin()(k
kk tkVtv
1
2
1
2
2 kkrms
k
krms V
VV
1
0
1
)sin()(k
kk
k
tkIti
1
2
1
2
11
2 kkrms
k
krms
kk
III
...)cos( 3211
avgavgavgk
kkkrmskrmsavg PPPIVP
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Totalharmonicdistortion(ordistortionfactor),
17
%100%1001
2
2
1
2
2
V
V
V
VTHD k
k
rms
kkrms
V
%100%100 22
2
2
II
THD kk
kkrms
I %00%0011 II rms
I
21 )100/(1 Vrmsrms THDVV 21 )100/(1 Irmsrms THDII
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Truepowerfactor,
1avgP
18
2211 )100/(1)100/(1
1
IVrmsrms
avgtrue
THDTHDIVPF
EXAMPLE4.2Calculatethetruepowerfactorforthefollowingmeasurements:Frequency (Hz) Voltage (V) Current (A)Frequency(Hz) Voltage(V) Current(A)
50 4150 5030150 9.525 1570250 5.840 5010350 1.235 5020
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCEffectofPFtrueonPowerLosses
19
3.004.005.006.007.008.00
wer
Losses
(pu)
NonLinearLoad
Linear Load
0.001.002.00
1.00 0.90 0.80 0.70 0.60 0.50 0.40
Pow
PF
LinearLoad
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC 20
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Averagepowerfactorvaluesforthemostcommonlyused
equipmentandappliances
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC
Why to improve
22
Reductionof losses
Reductionofcablesize
Reductioninthecostofelectricity
Whytoimprovethepowerfactor?
Increaseinavailablepower
Reductionofvoltagedrop
oflosses(kW)incables
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCFixedcapacitors Automaticcapacitorbankscto
r?23
Attheterminalsofinductivedevices(motors
andtransformers)
Atbusbars supplyingnumeroussmallmotors
Atthebusbars ofageneralpowerdistribution
board
Attheterminalsofaheavilyloadedfeederve
thep
ower
fac
andinductive
Incaseswherethelevelofloadisreasonably
constant
ycable
How
toim
prov
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC(Design)(Design)
IndentifySystemRequirements
24
CapacitorSizingConsiderharmonicscondition(capacitorvoltage > system voltage) frequency?
CalculatecompensatedQaccordingtothesystem needs
Totalsystemloading(P&Q) Frequencyandvoltage(system&capacitors) OverallPFandtargetPF
AnalysisforPossiblePQResonanceeffect? Switchingtransient?
voltage>systemvoltage),frequency? systemneeds.
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC(Design)(Design)
1121 QQQC 25
2111 costancostan PFPFP PFDesired
PFOriginal0.85 0.86 0.87 0.88
0.50
0 51
KFactor
0.51
0.52
0.53
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC(Design)(Design) Differencesinvoltage/frequencylevelbetweenthesupplysystem andthecapacitor usedwillproducedifferent injected reactive power into the system
26
differentinjectedreactivepowerintothesystem. Thefactortobeconsideredisasfollows:
where
2
S
CAPSCAP VVQQ
S
CAPSCAP f
fQQ
where,QCAP =EffectivereactivepowerprovidedbycapacitorQS =EffectivereactivepowerinjectedintosupplysystemVCAP =CapacitorvoltagelevelVS =Supplysystemvoltagelevel
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCEXAMPLE4.3
Incoming
27
Incoming3phase,50Hz,400V
M1 M2C1 C2
L1
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC 28
Component DescriptionM1 8unitsof3phaseinductionmotor,eachoneratedat2kVA,
0.78laggingpowerfactorwith88%efficiency.M2 24unitsofsinglephaseconveyormotor,connectedinbalance
3phasecoordination,eachoneratedat300W,0.82laggingpowerfactorwith78%efficiency.
L1 Lumploads,ratedat10kVAr,0.9laggingpowerfactor.C1 6 steps power factor corrector with the switching arrangementC1 6stepspowerfactorcorrectorwiththeswitchingarrangement
of(1:1:2:2:4:4).Theunitcapacitorusedisratedat525V,2kVAr.
C2 3stepspowerfactorcorrectorwiththeswitchingarrangementof(1:2:3).Theunitcapacitorusedisratedat440V.
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Analysetheaveragepowerfactorofthisfactorywhenboth
powerfactorcorrectors,C1andC2aredisabled.
29
RecommendtheproperkVAr ratingfortheunitcapacitorusedinC2ifthepowerfactorforthegroupmotorcircuit,M1istobecorrectedatleastto0.95lagging.AssumeC2isswitchedtostep3.
AnalyseagaintheaveragepowerfactorforthisfactoryifC1d C2 it h d t t 4 d t 2 ti landC2areswitchedtostep4andstep2,respectively.
IftheC1andC2inFigureareaccidentallyswitchedtoitsmaximumstepsandL1isdisconnectedduetotheshortcircuitevent,predicttheoverallpowerfactorforthisinstallation.
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCSomeissuesinPFCapplication:
30
Avoidnuisancetripscausebycapacitorswitchingtransients
Currentlimitingfusesat150%to175%ofthecapacitorratedcurrent
Capacitorshouldbedischargetoaresidualvoltageof50V,1minuteafteritisdisconnected
Greaterswitchingtransientswillberesulted if not
Avoidresonanceasitincreasestheheatinganddielectricstresses
Seriesresonancemightcausezerovoltageatsomefrequenciescurrent
Donotsettootightortooloose
Protection
resultedifnotproperlydischarged
CapacitorDischarge
frequencies Parallelresonanceswillamplifyharmonicsatspecificfrequencies
Harmonics
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC
SeriesSeries
31
SeriesSeriesResonanceResonance
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC
ParallelParallel
32
ParallelParallelResonanceResonance
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCResonance
33
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCWhentohavefiltertoeliminatetheharmonics?
34
Powerfactorcorrection(kvar)isgreaterthan25%ofthe transformer kVA
Harmonicproducingload(e.g.driveload)isgreaterthan40%ofthe transformer kVA
RISK
thetransformerkVA thetransformerkVANoproblemisexpectedifbelow15%
Noproblemisexpectedifbelow25%
kVArZkVA
hrtransforme
rtransforme
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCCAPACITORSWITCHINGTRANSIENTS Capacitor switching transient is a normal system
35
Capacitorswitchingtransientisanormalsystemeventthatcanoccurwheneveracapacitorisenergised.
Typically,deenergising acapacitordoesnotcauseasystemtransient.
Thetransientoccursbecauseofthedifferencebetweenthesystemvoltageandthevoltageonthecapacitor.
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Themagnitudeofthetransientwillvarybasedon two variables at the time of the switching.
36
ontwovariablesatthetimeoftheswitching.
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Thesevariablesaretheinitialvoltageonthecapacitor(trappedcharge,usuallyclosetozeroifthe
37
capacitorhasbeenallowedtodischarge)andtheinstantaneoussystemvoltageatthetimeoftheswitching.
Thegreaterthedifferencebetweenthesetwovoltages,thegreaterthemagnitudeofthetransient.h ll h h Theworstcasetransientwilloccurwhenthesystemvoltageisatpeakvoltageandthereisatrappedchargeonthecapacitorofpeaksystemvoltageattheoppositepolarity.
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC 38
LCVVI CStransient
Where,VS :Instantaneoussystemvoltage(V)VC :Instantaneouscapacitorvoltage(V)C:CapacitorvalueinFL:InductancevalueinH
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCBACKTOBACKCAPACITORSWITCHING This situation occurs when a second capacitor is
39
Thissituationoccurswhenasecondcapacitorisswitchedoninclose(electrical)proximitytoapreviouslyenergised capacitor.
Inthiscaseahigherfrequencytransientinitiallyoccursasthepreviouslyenergised capacitorsharesitschargewiththenewlyenergizedcapacitor.
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Figurebelowshowstheenergisation ofa50kVAr, 480 V capacitor step with trapped charge
40
kVAr,480Vcapacitorstepwithtrappedchargeandwith150kvar ofothercapacitorstepsinservice.
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BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFCMINIMISINGCAPACITORTRANSIENTS There are two basic ways to minimize capacitor
41
Therearetwobasicwaystominimizecapacitorswitchingtransients. Switchthecapacitoratapointintimewhenthesystemvoltagematchesthevoltageonthecapacitor,evenifthereisatrappedcharge.I i d i i d i Insertsomeimpedance,resistanceorinductance,inthecircuittominimise thetransient(limitthecapacitorinrushcurrent,thusminimising theresultingvoltageoscillation).
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems 42
Fundamental(50Hz) Fifthharmonic(250Hz)Thirdharmonic(150Hz) Resultingwaveform
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems 43
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems Thisperiodicphenomenon(harmonics)canberepresented by a Fourier series as follows:
44
representedbyaFourierseriesasfollows: nn
nn tnYYty
sin2)(
10
where:
Y = the amplitude of the DC component which is generally
Accordingtostandards,harmonicordersabove40 areneglected.
Y0 =theamplitudeoftheDCcomponent,whichisgenerallyzeroinelectricalpowerdistribution(atsteadystate),Yn =theRMSvalueofthenth harmoniccomponent,n =phaseangleofthenthharmoniccomponentwhent=0.
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsHarmonicssourcesinindustrialapplications:
45
pp Staticconverters(n=kp 1ofcurrentharmonics)
Arcfurnaces Lighting(dischargelampsorfluorescentlampsproducing3rd harmonics)
Variablespeeddrives Weldingmachines
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems Oneofthemostcommonharmonicssourcesinindustrial applications is rectifier loads.
46
industrialapplicationsisrectifierloads. TheharmonicloadcurrentdemandsofrectifiersmaybecalculatedfromtherectifierformulastofindI1,thenfindtheoddharmonics(Singlephase)or5,7,11,13th harmonics(sixpulse)
/using1/hrule
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsExample4.4A 1000 kVA three phase six pulse rectifier serves
47
A1000kVA threephasesixpulserectifierservesa2000VDCloadusingthedelayangletoholdtheDCvoltageconstantoverallloadsintherange100kWto250kW.Thesupplytransformerisratedat1100kVA,13.8kV/6900V,x=20%,50Hz.Estimatethefifthandseventhharmoniccurrentsonthehighvoltagesideofthetransformerinthe100kWand250kWoperatingrange.
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsSolution:Find transformer reactance
48
Findtransformerreactance, 28.43
1100)6900( 22
kVAV
SVX LLbase
656.828.432.0SS XL3)(23 S ILVV
)2
cos(
22)cos()cos(
)cos(
disp
LL
dcS
dcS
LLdc
PF
VIL
IVV
SixpulseRectifierFormula
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems At250kW,
49
003.71
2000250656.83cos6900232000
kW
22cos)cos(
LL
dcS
VIL
216.0)2/cos(042.13
)6900(2)2000/250)(656.8(2)003.71cos()003.71cos(
dispPF
kW
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
kVAkWPFPS 1157
2160250
50
AII
AVSI
PF
PLL
disp
68.951
405.483
216.0
15
)(1
AII 92.671
17
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems At100kW,
51
990.74
2000100656.83cos6900232000
kW
22cos)cos(
LL
dcS
VIL
2149.0)2/cos(206.5
)6900(2)2000/100)(656.8(2)990.74cos()990.74cos(
dispPF
kW
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
kVAkWPFPS 33.465
21490100
52
AII
AVSI
PF
PLL
disp
89.351
468.193
2149.0
15
)(1
AII 78.2715
17
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Summary
53
4
6
8
10
12
Harm
onic
Value(
A)
0
2
I5(250kW) I7(250kW) I5(100kW) I7(100kW)
Curren
t
HarmonicOrderbyApplicationPower
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
INSTANTANEOUS LONGTERM
CONSEQUENCESOFHARMONICS54
INSTANTANEOUSEFFECTS
Disturbcontrollers
LONGTERMEFFECTS
Additionalheatingoninductiveloads/equipment
Additionalerrorsininductiondiskelectricity
meters
Disturbprotectivedevices
Vibrationsandnoise
Interferenceoncommunicationandcontrol
circuits
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsSomesymptomscausedbyharmonics:
Voltagenotching
55
Erraticelectronicequipmentoperation Computerand/orPLClockups Overheating(motors,cables,transformers,neutrals) Motorvibrations Audiblenoiseintransformersandrotatingmachines Nuisancecircuitbreakeroperation Timingordigitalclockerrors Electricalfires Voltage/generatorregulatormalfunctioning
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsCompatibilitylevelsforvoltagetolerance,voltageunbalanceandpowerfrequencyvariations
56
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsHarmonicStandardforIndustrialNetworks IEC6100024:2002Oddharmonicsnonmultipleofthree
57
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsHarmonicStandardforIndustrialNetworks IEC6100024:2002Oddharmonicsmultipleofthree
58
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30
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsHarmonicStandardforIndustrialNetworks IEC6100024:2002Evenharmonics
59
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsCompatibilitylevelsfortotalharmonicdistortion
60
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31
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsHarmonicmitigationmethods:Passive filter (or tuned filter)
61
Passivefilter(ortunedfilter)ActivefilterMultipulse transformerHarmonicsmitigationtransformer
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Passivefilter
62
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems TunedFilter
Xf 1
63
LCXX
ffh
L
Cnn
00
1
CC Q
kVX2
CLXXX /XR n CLXXX CLn /Q
R n
22 /)(
/)(
hXhXRhZ
hXhXjRhZ
CLF
CLF
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsEXAMPLE4.5A series filter is tuned to the 11th harmonic
64
Aseriesfilteristunedtothe11th harmonic.GivenXC =405Ohm.Calculatethefilterelements.Takethequalityfactor(Q)as50.
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystemsEXAMPLE4.6What is the tuning order and the quality factor
65
Whatisthetuningorderandthequalityfactorfora36kVseriestunedfilterwithXC =544.5Ohms,XL =4.5OhmsandR=0.825Ohms?
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Activefilter
66
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems 67
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Multipulse transformer
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Multipulse transformer
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Harmonicsmitigationtransformer
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BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems 70
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysis 71
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisIEEEStd.11591995/MSIEC61000
72
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysis Maincausesofvoltagesagsinindustrialpowersystems:
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systems: Faults inthesystem,includinglightningstrike Transformerenergising Heavyloadswitching,mainlylargemotor (>300HP)
Typesofvoltagesags: Sudden SinglePhaseSags PhasetoPhaseSags ThreephaseSags
QEXAMPLEStartinglargemotorsorbyelectricalfaultsinsidethefacility
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisSinglePhaseSags The most common voltage sags over 70% are single
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Themostcommonvoltagesags,over70%,aresinglephaseeventswhicharetypicallyduetoaphasetogroundfaultoccurringsomewhereonthesystem.Thisphasetogroundfaultappearsasasinglephasevoltagesagonotherfeedersfromthesamesubstation Typical causes are lightning strikes treesubstation.Typicalcausesarelightningstrikes,treebranches,animalcontactetc.Itiscommontoseesinglephasevoltagesagsto30%ofnominalvoltageorevenlowerinindustrialplants.
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisPhasetoPhaseSags 2 Phase phase to phase sags may be caused by
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2Phase,phasetophasesagsmaybecausedbytreebranches,adverseweather,animalsorvehiclecollisionwithutilitypoles.Thetwophasevoltagesagwilltypicallyappearonotherfeedersfromthesamesubstation.
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisThreephaseSags Symmetrical3phasesagsaccountforlessthan20%
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y p gofallsageventsandarecausedeitherbyswitchingortrippingofa3phasecircuitbreaker,switchorrecloser whichwillcreatea3phasevoltagesagonotherlinesfedfromthesamesubstation.3phasesagswillalsobecausedbystartinglargemotors butthis type of event typically causes voltage sags tothistypeofeventtypicallycausesvoltagesagstoapproximately80%ofnominalvoltageandareusuallyconfinedtoanindustrialplantoritsimmediateneighbours.
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysis
Metering systems? Motor quality? Speed
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Meteringsystems?Monitoringsystems?Accuracyproblems?
Motorquality?Speedvariation?Motordrives
effects?
EFFECTSOFVOLTAGESAGS
ControlSystem?PLC?Electronicprocesscontrols?Sensors?Computercontrols?
VSD?
Industrialprocesses?Manufacturingstoppage?
Restartproduction?
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysis Thedipmagnitudeduringafaultisdependenton two impedances, the source impedance, ZS
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ontwoimpedances,thesourceimpedance, ZSandtheimpedancetothefault,ZF
EZZ
ZVFS
FPCC
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4.4VoltageSagAnalysis4.4VoltageSagAnalysis Industrialcustomerswhohaveinvestedheavilyin production equipment which is susceptible to
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inproductionequipmentwhichissusceptibletovoltagesagsmusttakeresponsibilityfortheirownsolutionstovoltagesagsorlosesomebenefitfromtheirinvestment.
ReplacementofcomponentsorVoltagesagsareafactoflifetheycannotreadilybeeliminatedfromregularutilitysystems.
devices,whichareespeciallysensitive,withlessvoltagesensitivesubstitutesorinstallationofsomeformofprotectionagainstvoltagesags.
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisIdentifytheProblem
MeasuretheProblem
ChooseaSolution
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EquipmentIdentification
Whichequipmentissusceptibletounplannedstoppages?
IdentifytheVoltageSags
Determine the
InstallMetering Installationofanelectronicmeterwithwaveformcapturecapability
RecordUnplannedProductionStoppages
Calculatethetypeofvoltagesagcorrectionofexpectedfuturevoltagesagevents
CorrecttheproblembychangingsomeDeterminethe
frequency,depthanddurationofthevoltagesags
pp g MeterCostvs.CostofUnplannedProductionStoppage
sensitivecomponents
IdentifythesizeoftheloadtobeprotectedinkVAanditssupplyvoltage
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4.4VoltageSagAnalysis4.4VoltageSagAnalysis Somepossiblevoltagesagscorrectionmethods:
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FerroresonantTransformer
UninterruptiblePowerSupply
(UPS)
FlywheelandMotor
Generator(MG)
DynamicVoltage
Restorer(DVR)StaticVar
Compensator(SVC)
SagProofingTransformers
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisFerroresonant Transformer Also known as a constant voltage transformer (CVT), is a
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Alsoknownasaconstantvoltagetransformer(CVT),isatransformerthatoperatesinthesaturationregionofthetransformerBHcurve.
Voltagesagsdownto30%retainedvoltagecanbemitigatedusingthistechnique.
Ferroresonant transformersareavailableinsizesuptoaround25kVAkVA.
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisUninterruptiblePowerSupply(UPS) UPS mitigate voltage sags by supplying the load using stored
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UPSmitigatevoltagesagsbysupplyingtheloadusingstoredenergy.
Upondetectionofavoltagesag,theloadistransferredfromthemainssupplytotheUPS.
BlockDiagramofanofflineUPS BlockDiagramofanonlineUPS
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisFlywheelandMotorGenerator(MG) Flywheel systems use the energy stored in the inertia of a rotating
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Flywheelsystemsusetheenergystoredintheinertiaofarotatingflywheeltomitigatevoltagesags.
Theflywheelisacceleratedtoaveryhighspeedandwhenavoltagesagoccurs,therotationalenergyofthedeceleratingflywheelisutilised tosupplytheload.
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4.4VoltageSagAnalysis4.4VoltageSagAnalysisDynamicVoltageRestorer(DVR) DVRinjectsvoltageintothesystemin
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ordertobringthevoltagebackuptothelevelrequiredbytheloadduringvoltagesag.
Injectionofvoltageisachievedbyaswitchingsystemcoupledwithatransformerwhichisconnectedinserieswith the loadwiththeload.
ThedifferencebetweenaDVRwithstorageandaUPSisthattheDVRonlysuppliesthepartofthewaveformthathasbeenreducedduetothevoltagesag,notthewholewaveform.
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisStaticVar Compensator(SVC) A SVC is a shunt connected power electronics based device
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ASVCisashuntconnectedpowerelectronicsbaseddevicewhichworksbyinjectingreactivecurrentintotheload,therebysupportingthevoltageandmitigatingthevoltagesag.
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisSagProofingTransformers Also known as voltage sag
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Alsoknownasvoltagesagcompensators,arebasicallyamultiwindingtransformerconnectedinserieswiththeload.
Effectiveforvoltagesagstoapproximately40%retainedvoltage.g
Onlyavailableforrelativelysmallloadsofuptoapproximately5kVA.
BEF44903 IndustrialPowerSystems Topic4
4.5FlickerAnalysis4.5FlickerAnalysis Flickerisdefinedasthevariationintheluminosityproducedinalightsourcebecauseoffluctuationsin
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p gthesupplyvoltage.
Themainsourcesofflickerarelargeandfastloadvariationsindustrialloads,suchaselectricarcfurnaces,motors,rollingmills,mashwelders electric welders and electric boilerswelders,electricwelders,andelectricboilers.
Thevoltageflickerischaracterised byvariationofvoltagemagnitudeintherangeof10%ofnominalvoltageandwithfrequencies between0.2to30Hz.
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BEF44903 IndustrialPowerSystems Topic4
4.5FlickerAnalysis4.5FlickerAnalysis Rectangularfluctuationatafrequencyof8.8Hzandanamplitude
V=0.4V(i.e.,V/V=40%),whichmodulatesamainssignalof50 H d li d V 1 V
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50HzandamplitudeV=1V.
BEF44903 IndustrialPowerSystems Topic4
4.5FlickerAnalysis4.5FlickerAnalysis 90