2014 IEEE Interational Conference on Advanced Communication
Control and Computing Technologies(lCACCCT) Performance
AnalysisofaTwo-DiodemodelofPV cellforPVbasedgenerationinMA TLAB
A.V.Pavan Kumari,Alivelu M.Parimi2,K.Vma Rao3 iResearchScholar, 2
Assistant Professor, 3Professor i,2Dept. of EE,BITS-Pilani,
Hyderabad Campus,Hyderabad,AP, India 3R V College of Engineering,
Mysore Road, Bangalore, Karataka, India.
[email protected],[email protected],[email protected]
Abstract-Theincreaseinconcernforcarbonemissionand
reductioninnaturalresourcesforconventionalpower
generation,therenewableenergybasedgenerationsuchas Wind,
Photovoltaic(PV),andFuelcellhasgainedimportance.Outof
whichthePVbasedgenerationhasgainedsignifcancedueto
availabilityofabundantsunlight.AstheSolarpowerconversion
isalowefcientconversionprocess,accurateandreliable,
modelingofsolarcellisimportant.Duetothenon-linearnature
ofdiodebasedPVmodel,theaccuratedesignofPVcellisa
difculttask.Abuilt-inmodelof PVcellisavailableinSimscape,
Simelectronicslibrary,Matlab.Theequivalentcircuit
parametershavetobecomputedfromdatasheetand
incorporatedintothemodel.Howeveritactsasastiffsource
whenimplementedwithaMPPTcontroller.Henceforth,to
overcomethisdrawback,inthispaperatwo-diodemodelofPV
cellisimplementedinMatlabSimulinkwithreducedfour
requiredparametersalongwithsimilarconfgurationofthe
built-inmodel.ThismodelallowsincorporationofMPPT
controller.TheI-VandP-Vcharacteristicsofthesetwomodels
areinvestigatedunderdifferentinsolationlevels.APVbased generation
systemfeedingaDCloadisdesignedandinvestigated
usingthesetwomodelsandfurtherimplementedwithMPPT
basedonP&Otechnique.
Keywords:Two-diodemodel,1modeling,1powergeneration,
MATBISimulink,Solar insolation. I.INTRODUCTION
Theincreaseintheuseofconventionalenergysources
causesthepossibilityoftheirenervationandincreasein
carbonemission.Theglobalenergyconsumptionisamassed exponentially.
Theneedofcleanenergygenerationwithless
environmentalimpactisrequired.Therenewableenergy
sourcessuchassolarenergy,Windenergy,Fuelcell,Geothermal energy,
Tidalenergyaregainingimportance.Among
theserenewableenergysources,despiteofhighinstallation
cost,theenergyproducedfomthephotovoltaiciscurrently
regardedastheprerequ isitesustainableresourcesforboth
standaloneandgridconnectedsystem,sinceitoferszero
inputfelcost,richandcleanenergy.Nonetheless,thiskind
ofalteratingpowergenerationcausesproblemsinthe
conventionalelectricalsystemwhereitwillbeconnectedto,
becauseofthedearthofcontrolontheactiveandreactive
powergeneration.Inordertoovercometheshortcomings,the
potentialofPVpowergenerationshouldbeinvestigatedby selecting
appropriate PV module. Numerous studies havebeen absorbedover
thedemonstrationof PVmodulecharacteristics ISBN No.
978-1-4799-3914-5/14/$3l.002014 IEEE andsimulatedforbetter
understandingoftheirperformances. Ontheotherhand, choosing theright
controlling techniqueis
neededinordertoachieveaneffcientrenewableenergy system[1-3].
TheoutputpowerofaPVmoduleisrelatedtoambient
temperatureandsolarirradiation,whicharethemajor
componentsofthemathematicalmodelof PVcellthataffect
theaccuracyinthesimulation.Amongthevarious
mathematicalmodelsofPVcellproposedintheliterature,
simplemodelisasinglediodemodelof PVcellconsistingof
shortcircuitcurrent(lse) ,opencircuitvoltage(Voe)andthe
diodeidealityfactor(N).Variousresearchershaveproposed
differentmodifedmathematical modelsof PVcellin order to
produceaccurateCurent-Voltage(I-V), Power-Voltage(P-V)
characteristics similar to the manufacturer PVpanel[4-7].Out
ofwhichatwo-diodemodelof PVcellisconsideredinthis
paper.ThebehaviorofthePVcellisinvestigatedunder
differentsolarinsolationlevels,bycalculatingthevaluesof
Seriesresistance(Rs),Shuntresistance(Rp)byiteration
methodtostudytheperformanceofthe PVcell.ASolarcell
blockhavingatwo-diodemodelconfgurationisalsoinbuilt
inSimscape,Simelectronics libraryin Matlab.
ThetwoPVcellmodelsbasedondiodesandits
confguration(inSimscape)areconsideredandbyselecting
optimumvalues,anaccurateoutputsimilartotheindustrial manufacturer
PVdatasheetisproducedandcompared.Later
thePVbasedgenerationissimulatedusingboththe
confgurationsofPVmodelstoformonemodelwithfour parameters. This PV
generationsystem withMaximum Power
PointTracking(MPPT)controllerbasedonPerturband
Observe(P&O)algoritlun feedingaDCloadis analyzed.In
thiscontextamathematicalmodeloftwodiode PVcellis discussed in
section II. Section III discussed the PV cell model inSimscape. The
characteristics of these models are compared
withmanufacturedatasheetinsectionIV.SectionV
integratesthesetwomodelsfor PVbasedgenerationsystem
andimplementedwithMPPTcontroller.SectionVIgives shows the
efectiveness of this system connected to a DC load.
II.MATHEMATICALMODELINGOFTWO-DIODE PV CELL
Inordertosimulatetherealbehaviorofatwo-diode PV
cellinMATLAB/Simulinkmathematicalmodelneedtobe
developed.Anelectricalequivalentcircuitisessentialto
analyzetheperformanceof PVcell. Theequivalentcircu itof two-diode
PVcellisasshowninFig.1consistingof Photo-68 2014 IEEE Interational
Conference on Advanced Communication Control and Computing
Technologies(lCACCCT)
generatedcurrent(lph),twodiodeswithdiodecurrents(ld\, I__).
SeriesResistance(Rs),ShuntResistance(Rp),output voltage (V) and PV
curent (I or Ipv). Fig.. EquivalentCircuitof Two-diode model of PV
cell ThegraphicalinterfaceoftheMATLAB,Simulinkhelps
ustodevelopandinvestigatethemathematicalmodelofthe two-diode PV
cell whichcannot be interpreted by looking into
manufacturerdatasheet.Thiselectricalequivalentcircuitof
PVcellisknowntocompriseimprovedaccuracyatlow
irradiationlevelswhichhelpsusformoreaccurateprediction
ofPVsystemperformanceunderdifferentenvironmental conditions when
compared to manufacturer datasheet[8, 9]. In Fig. 1, which showsthe
equivalent circuit oftwo diode model of PVcell the relation between
output current and voltage can
beobtainedbyapplyingKirchhoffscurrentlaw(KCL)and govered by (1)
!'!j!|!!S (1) Where, I,I_are the currents of the diodes D"D_.
+!11_!_(2) Equation(2)istheelementary PVcellmodelwhichdoes
notrepresentthepracticalI-Vcharacteristicsofthe PVcell. Practical
PV module comprisesof different elements that need tobe added into
theelementary(2)suchasRs, Rp. Theoutput current of PV cell (2) is
rewritten as(3) [ ( 1! `1J][ ( 1! `1J] !+!!j 1!_1`j`
`_`!`!_!_where, k Boltzmann constant l.38` _ J/K, Q charge on
electron 1.602 ` 10C, (3) 1
Photocurrent,fnctionofirradiationleveland junction temperature, A,
!!_ Reverse Saturation current of diodes D\, D2, A, 1 Reference
cell operating temperature, 20C ! Cell output voltage, V, . number
of PV cells connected in series, N], N_ Ideality factors of diodes
D],D_. The output curent of the PV cell represented by(3) is that
ofsingle PVcell.Inordertoachievedesiredlevelofoutput
voltageandcurrentthePVcellareconnectedinseriesand parallel.Ifthe
PVmodulesconsistofNpparallelconnected cells, the output current of
the PV module is expressed as: !','/,!' ^ .'(4)
InordertosimulatethePVcellbehaviorsimilartothe practical PV cell
the unknown parameters in(3)i.e., R., Rp are calculated by
iteration[10]. The computed valuesof Rs and Rp
areusedtomakethemaximumpointoftheP-Vcurve simulated to coincide
with themaximumpoint of the practical P-V curve of the PV module
takenfom datasheet. This can be
achievedbyiterativelyincreasingthevaluesofRsand
simultaneouslycalculatingthe value of Rp. Computation of the
iterativevalueswillterminatewhenthecalculatedpower P ____ using
these values equals the reference maximum power P ___ taken fom the
datasheet. III.PV CELL MODEL INSIMSCAPE,SIMELECTRONICS The solar
cellblock intheSimelectronicslibraryshown in Fig. 2ismodeledonthe
basis oftwodiodeequivalentcircuit of
PVcellasshowninFig.1.Theoutputcurrentofthe PV cell is given by (3).
COHI LGFig.2.Solarcell block in Simscape/Simelectronics library
Thesolarcellblockhasthreedifferentconfgurations
inbuilt(a)BySICCurrentandOIC Voltage, 5paameter,(b)
Byequivalentcircuitparameters,5parameter,(c)By
equivalentcircuitparameters,8parameter.Outofthethree
confgurations'byequivalentcircuitparameters,8parameter' is selected
whichis similarto that of equation based two-diode model of PV cell
discussed in section II. IV.I-V & P-V CHARACTERISTICS OF PV
CELL MODELS COMPAREDWITH MANUFACTURER DATA SHEET
SharpNU-E245(J5)solarpanelisselectedforthe
MATLABsimulation.Themodelconsistsof50cellsof Silicon
nitridemulti-crystalline silicon cells.Fig. 3 shows the I-V and P-V
characteristics taken fom the data sheet [11].The electrical
parameters of theSX 3200are shown in Table. I. cLrS. jce1 ^ \
