3IMULATION OF 'RID #ONNECTED 0HOTOVOLTAIC 3YSTEMS
!THULA 2AJAPAKSE $EPARTMENT OF %LECTRICAL AND #OMPUTER %NGINEERING
5NIVERSITY OF -ANITOBA 7INNIPEG #ANADA
2ISING ATTENTION TO DISTRIBUTED GENERATION $'
AND GREEN ENERGY ALTERNATIVES TO CONVENTIONAL
FOSSIL FUEL BASED ELECTRICITY HAS REVIVED THE INTER
EST IN GRID CONNECTED PHOTOVOLTAIC 06 SYSTEMS
!S THE COST OF 06 HAS COME DOWN APPLICATIONS
SUCH AS BUILDING INTEGRATED 06 SYSTEMS ARE
BECOMING INCREASINGLY POPULAR ;= 7HEN LARGER
06 INSTALLATIONS ARE DESIGNED STUDIES NEED TO BE
PERFORMED AT THE POWER SYSTEM LEVEL TO EXAMINE THE
IMPACTS OF INTEGRATION &OR SMALL SCALE DISTRIBUTED
GENERATION INTERCONNECTION STANDARDS SUCH AS )%%%
;= AND LOCAL UTILITY INTERCONNECTION
REGULATIONS DElNE THE GRID INTERFACE REQUIREMENTS
4HE PROTECTION IS BASED ON THE PHILOSOPHY THAT IN CASE
OF GRID DISTURBANCES EG VOLTAGE DROPS OR FREQUENCY
DEVIATION DISTRIBUTED GENERATORS WILL BE DISCONNECTED
FROM THE NETWORK IMMEDIATELY 4HE PROTECTION AT THE
GRID INTERFACE AND THE $' CONTROL MUST BE DESIGNED TO
MEET REQUIREMENTS 03#!$š%-4$#© CAN BE USED FOR
STUDIES INVOLVING CONTROLLER TUNING PROTECTION SETTING
POWER QUALITY INVESTIGATIONS AND SYSTEM VALIDATIONS
AMONG OTHERS ;=
06 !RRAY -ODEL ! SOLAR CELL CAN BE MODELLED USING
AN ELECTRICAL EQUIVALENT CIRCUIT THAT CONTAINS A CURRENT
SOURCE ANTI PARALLEL WITH A DIODE A SHUNT RESISTANCE
AND A SERIES RESISTANCE AS SHOWN IN &IGURE A 4HE $#
CURRENT )G GENERATED WHEN THE CELL IS EXPOSED TO LIGHT
VARIES LINEARLY WITH SOLAR IRRADIANCE
&IGURE B 06 CELL TYPICAL ) 6 CHARACTERISTICS
4HE BASIC EQUATION THAT CHARACTERIZES THE SOLAR CELL ) 6
RELATIONSHIP CAN BE DERIVED CONSIDERING THE EQUIVALENT
CIRCUIT SHOWN IN &IGURE 4HE +IRCHOFFS CURRENT LAW
PROVIDES
3UBSTITUTION OF RELEVANT EXPRESSIONS FOR THE DIODE
CURRENT )D AND THE SHUNT BRANCH CURRENT )SH YIELDS
)N )SC IS THE PHOTO CURRENT AND IT IS A FUNCTION OF THE
SOLAR RADIATION ON THE PLANE OF THE SOLAR CELL ' AND THE
CELL TEMPERATURE 4C
WHERE )SC2 IS THE SHORT CIRCUIT CURRENT AT THE REFERENCE
SOLAR RADIATION '2 AND THE REFERENCE CELL TEMPERATURE
4C2 4HE PARAMETER ?4 IS THE TEMPERATURE COEFlCIENT
OF PHOTO CURRENT 4HE CURRENT )O IN IS CALLED THE
DARK CURRENT A FUNCTION OF CELL TEMPERATURE ONLY
AND IS GIVEN BY
&IGURE A 06 CELL EQUIVALENT CIRCUIT
4HE CURRENT )D THROUGH THE ANTI PARALLEL DIODE IS
LARGELY RESPONSIBLE FOR PRODUCING THE NONLINEAR ) 6
CHARACTERISTICS OF THE 06 CELL &IGURE B 05,3% 4(% -!.)4/"! (6$# 2%3%!2#( #%.42% */52.!,
WHERE )O2 IS THE DARK CURRENT AT THE REFERENCE
TEMPERATURE 4HE OTHER PARAMETERS APPEARING
IN ARE THE ELECTRON CHARGE Q THE "OLTZMANN
CONSTANT K THE BAND GAP ENERGY OF THE SOLAR CELL
MATERIAL EG AND THE DIODE IDEALITY FACTOR N
3IMULATION OF A 'RID #ONNECTED 06 )NVERTER
! SIMPLE EXAMPLE OF USING THESE COMPONENTS FOR A
SYSTEM STUDY IS SHOWN IN &IGURE 4HE EXTERNAL GRID IS
REPRESENTED BY ITS 4HEVENINS EQUIVALENT "ASIC BLOCKS
OF THE -00 4RACKING CONTROL ARE SHOWN IN &IGURE !LL OF THE CONSTANTS IN THE ABOVE EQUATIONS CAN BE
DETERMINED BY EXAMINING THE MANUFACTURERS SPECIl
CATIONS OF THE 06 MODULES AND PUBLISHED OR MEASURED
) 6 CURVES ! 06 ARRAY IS COMPOSED OF SERIES AND PARAL
LEL CONNECTED MODULES AND THE SINGLE CELL CIRCUIT CAN BE
SCALED UP TO REPRESENT ANY SERIESPARALLEL COMBINATION
! 06 CELL MODEL BASED ON THE ABOVE EQUATIONS WAS
IMPLEMENTED AS A CUSTOM COMPONENT IN 03#!$š
-AXIMUM 0OWER 0OINT 4RACKING 4HE AMOUNT OF
POWER THAT CAN BE DRAWN BY A SOLAR CELL DEPENDS ON
THE OPERATING POINT ON THE ) 6 CURVE AND THE MAXI
MUM POWER OUTPUT OCCURS AROUND THE KNEE POINT OF
THE CURVE ! MAXIMUM POWER POINT TRACKER -004 IS
A POWER ELECTRONIC $# $# CONVERTER INSERTED BETWEEN
THE 06 ARRAY AND ITS LOAD TO ENSURE THAT THE 06 MODULE
ALWAYS OPERATES AT ITS MAXIMUM POWER POINT AS THE
TEMPERATURE INSOLATION AND LOAD VARY ! POPULAR
-004 ALGORITHM BASED ON THE )NCREMENTAL #ONDUCT
ANCE ;= METHOD WAS IMPLEMENTED IN 03#!$š
&IGURE 3IMPLE $# $# CONVERTER CONTROL WITH --0 TRACKING
ATHULA EEUMANITOBACA
2EFERENCES
;= 0AUL -AYCOCK AND 4RAVIS "RADFORD h06 4ECHNOLOGY 0ERFORMANCE
AND #OST 5PDATE 2EPORT v PRODUCED BY 0ROMETHEUS )NSTITUTE
FOR 3USTAINABLE $EVELOPMENT AND 06 %NERGY 3YSTEMS #AMBRIDGE
-! 53!
;= h)%%% 3TANDARD FOR )NTERCONNECTING $ISTRIBUTED 2ESOURCES WITH
%LECTRIC 0OWER 3YSTEMS v )%%% 3TANDARD n
;= ! $ 2AJAPAKSE $ -UTHUMUNI . 0ERERA AND + 3TRUNZ
h%LECTROMAGNETIC 4RANSIENTS 3IMULATION FOR 2ENEWABLE %NERGY
)NTEGRATION 3TUDIES v 0ROCEEDINGS OF )%%% 0%3 !NNUAL -EETING
4AMPA &, 53! n *UNE ;= (USSEIN +( -UTA ) (OSHINO 4 /SAKADA - h-AXIMUM
0HOTOVOLTAIC 0OWER 4RACKING !N !LGORITHM FOR 2APIDLY #HANGING
!TMOSPHERIC #ONDITIONS v 'ENERATION 4RANSMISSION AND $ISTRIBUTION
)%% 0ROCEEDINGS 6OLUME )SSUE *AN 0AGES n
&IGURE 06 SYSTEM SIMULATION COMPONENTS LIBRARY
&IGURE %XAMPLE OF SIMULATING A GRID CONNECTED 06 SYSTEM SIMULATION
/#4/"%2