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SUBJECT : INDUSTRIAL POWER SYSTEMBEF 44903Industrial Power Systems is a must-have course for anyone involved in power engineering, especially in the design and maintenance of power distribution systems. This course is arranged to furnish students’ understanding of the utilisation of electrical energy in industrial applications. The industrial power distribution system generally represents a relatively small portion of the entire plant cost (5% to 10%), yet the production and output of the other 90% to 95% ofplant investment is dependent on the service delivered by that investment in the power distribution system. Thus, it is vital for a power engineer to know the features and design procedures of industrial power systems, including basic plant planning, load estimation, instrument transformers, protective devices, power cables, power monitoring and control, as well as the energy management and control.
Citation preview
11/3/2014
1
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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3
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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4
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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11
BEF44903 IndustrialPowerSystems Topic4
4.2ApplicationofIndustrialPFC4.2ApplicationofIndustrialPFC Averagepowerfactorvaluesforthemostcommonlyused
equipmentandappliances
21
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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17
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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18
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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19
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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20
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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21
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
11/3/2014
22
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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24
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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26
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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27
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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28
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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32
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
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Whatisthetuningorderandthequalityfactorfora36kVseriestunedfilterwithXC =544.5Ohms,XL =4.5OhmsandR=0.825Ohms?
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Activefilter
66
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4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems 67
BEF44903 IndustrialPowerSystems Topic4
4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Multipulse transformer
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Multipulse transformer
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4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems
Harmonicsmitigationtransformer
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4.3HarmonicsTreatmentin4.3HarmonicsTreatmentinIndustrialPowerSystemsIndustrialPowerSystems 70
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BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysis 71
BEF44903 IndustrialPowerSystems Topic4
4.4VoltageSagAnalysis4.4VoltageSagAnalysisIEEEStd.11591995/MSIEC61000
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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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BEF44903 IndustrialPowerSystems Topic4
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
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