Modified Version of Senior Project

8/19/2019 Modified Version of Senior Project

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Simulation of Photovoltaic System using

Matlab/Simulink

Senior Project II

Submitted to the Faculty of

Engineering and Information Technology at the

Arab American niversity ! "enin

In #artial fulfillment of

$achelor of Science degree

$y%

Naser Ayman Alshafei

Samah Tawfeeq

nder the su#ervision of%

Dr. Osama Omari

March &'()


2/33

Arab American niversity !"enin

Faculty of Engineering and Information

Technology

Simulation of Photovoltaic System using

Matlab/Simulink

$y%

Naser Ayman Alshafei

Samah Tawfeeq

nder the su#ervision of%

Dr. Osama Omari

March &'()

I


3/33

*eclarationI certify that this work contains no material which has been accepted

for the award of any other degree or diploma in my name, in any

ni!ersity or other tertiary instittion and, to the best of my knowledge and

belief, contains no material pre!iosly pblished or written by another

person, e"cept where de reference has been made.

Stdent#s signatres$

Naser Ayman Alshafei$ %%%%%.

Samah Tawfeeq$ %%%%%.

Sper!iser signatre

Dr. Osama Omari$ %%%%%.

II


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Table of +ontents,IST -F FI.ES00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000I1

,IST -F TA$,ES0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001

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+3APTE (% I2T-*+TI-2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000(

&.& 'A()*+OND.................................................................................................................&

&.- /OTO0O1TAI( 203 (411..............................................................................................&

&.5 0 (411 6OD41..............................................................................................................5

&.7 4884(TS O8 I++ADIAN(4 AND T464+AT+4 ON 0 (411S..........................................9

&.9 6A:I66 O;4+ OINT T+A()IN* 26T3.................................................................<

+3APTE &% P1 S4STEM E5IEME2TS000000000000000000000000000000000000000000000000000000000000000000000000('

-.& 0 S=ST46 D4SI*N +O(4D+4...................................................................................&>

-.- *+ID?(ONN4(T4D 0 S=ST46S....................................................................................&&

-.5 STAND?A1ON4 0 S=ST46S..........................................................................................&-

+3APTE 6% SIM,ATI-2 A2* ES,TS0000000000000 00000000000000 00000000000000 000000000000000 00000000000000 00000(6

5.& 0 (411 6OD41...........................................................................................................&5

5.- (ON(1SION.................................................................................................................-7

EFEE2+ES0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000&7

III


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,ist of Figures8igre &?&$ cross section of a silicon 0 cell......................................................................-

8igre &?-$ Single diode model of the 0 cell....................................................................5

8igre &?5$ 0? cr!es of a 0 cell at different Temperatre and Irradiances....................@

8igre &?7$ 0? cr!e of the 0 cell with 6...................................................................

8igre &?9$Impp?0mpp characteristics of the 0 cell...............................................................

8igre -?&$ maBor 0 systems components ......................................................................&>

8igre -?-$ grid?connected 2grid?forming3 0 system with battery backp ....................&&

8igre -?5$Stand?alone 0 system ...................................................................................&-

8igre 5?&$Simlink 0 cell modle ................................................................................ &-

8igre 5?-.&$I0 cr!e at 9>>)wCm- ................................................................................. &-

8igre 5?-.-$ I0 cr!e at &>>>)wCm- ............................................................................. &-

8igre 5?-.5$ I0 cr!e at ->>>)wCm- ............................................................................. &-

8igre 5?5.&$ I0 cr!e at -.&9 ) .................................................................................. &-

8igre 5?5.-$ I0 cr!e at 5-5.&9 ) .................................................................................. &-

8igre 5?5.5$ I0 cr!e at 57.&9 ) .................................................................................. &-

8igre 5?7.&$ 0 cr!e at 9>>)wCm- .............................................................................. ->8igre 5?7.-$ 0 cr!e at &>>>)wCm- ............................................................................ ->

8igre 5?7.5$ 0 cr!e at ->>>)wCm- ............................................................................ -&

8igre 5?9.&$ 0 cr!e at -.&9 ) .................................................................................. -&

8igre 5?9.-$ 0 cr!e at 5-5.&9 ) .................................................................................. --

8igre 5?9.5$ 0 cr!e at 57.&9 ) .................................................................................. --

I0


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,ist of TablesTable 5?&$ ST( constants !ales and their discriptions .....................&7

0


7/33

,ist of Abbreviations0$ hoto!oltaic

D($ Direct (rrent

A($ Alternating (rrent

6$ 6a"imm ower oint

6T$ 6a"imm ower oint Tracking

0$ ltra!iolet

I*'T$ Inslated *ate 'ipolar Enction Transistor

6OS84T$ 6etal?O"ide 8ield 4ffect Transistor

ST($ Standard Test (ondition

0I


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Abstract

;ith the rapid growth of power, the se of solar energy in electric

power applications is gradally increasing. One of those applications are the

photo!oltaic cells.

This stdy discsses the operation of photo!oltaic cells. And their

crrent F !oltage characteristic cr!es. The non?linearity of those cr!es

implies the tiliGation of efficient ma"imm power point tracker. ;hich

tracks the ma"imm possible power at any instant of time.

The direct?crrent natre of the photo!oltaics reqires the se of

in!erter to obtain an alternating?crrent which is more sitable for power

transmission.

8inally a simlation is presented sing 6AT1A'CSimlink software,

to !isaliGe and !erify the beha!ior of the main photo!oltaic system

components.

0II


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+ha#ter (% Introduction

(0( $ackground

+ecent Increase on the demand of power has raised a lot of qestion

abot the a!ailability of non?renewable power resorces and their impact on

the en!ironment. This led scientists and engineers to search for more

sstainable, cleaner, en!ironment?friendly and cost effecti!e power sorces

H&.

Among all renewable energy sorces, solar power systems attract

more attention becase they pro!ide e"cellent opportnity to generate

electricity while green hose emissions are redced and also it e"hibits

many merits sch as cleanness, little maintenance and no noise H-.

hoto!oltaic 203 technology is prominent way for har!esting solar

energy. 'ecase electrical power can be prodced withot any transitional

states sch as heat or mechanical. In addition to the compactness and

portability of this technology.

In the ne"t section the basic bilding block of 0 systems, namely the

0 cell will be discssed.

(0& Photovoltaic 8P19 cell

A solar cell is basically a p?n Bnction fabricated in a thin wafer of

semicondctor H-. The Bnction is made of materials that allow for the

photo!oltaic 203 effect to happen.

The 0 effect is the basis of the con!ersion of light to electricity in

photo!oltaic cellH5, when light hits the 0 cell it gi!es away some of its

energy to nearby electrons. A bilt?in?potential barrier in the cell acts on

&


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these electrons to prodce a !oltage, which can be sed to dri!e a direct

crrent 2D(3 throgh a circit.

8igre &?& shows the cross section of a 0 cell. ;hen light hits the N?

type material 2e.g. Selenim3H-, it e"cites the electrons ths pro!iding a

crrent that is collected by a metallic grid placed across the 0 cell as

shown in the right side of figre &?&.

Figure (:(% cross section of a silicon P1 cell

Silicon wafers sed for prodcing high qality 0 cells are made from

mono?crystalline silicon which is pre silicon with niform crystalline

lattice. Opposed to mlti?crystalline silicon which is less niform. The

efficiency of the former is higher by -?5J H7.

It is worth to mention that the most impressi!e of 0 impro!ements

and applications lies within nanotechnology, which allowed scientists to

create a plastic spray?on 0 cell that can tiliGe the sn#s infrared, in!isible

rays.

'ecase the infrared spectrm is tiliGed, solar cells can generate

electricity e!en on a clody day. Similar to paint, this composite can be

simply sprayed onto almost any material to ser!e as portable electricity H9.

-


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0 cells are often groped in modles 2in series3 to increase their

otpt crrent. Se!eral modles also can be connected in parallelCseries to

form an array or so called string. The more power is reqired by the 0

system, more 0 panels 2arrays3 are connected to that system H7.

(06 P1 cell model

In order to nderstand the beha!ior of the 0 cell, scientists and

engineers ha!e de!eloped !arios models to conclde the 0oltage?crrent

characteristics of the 0 cells in different en!ironments and conditions.

The most widely sed mathematical model for a single 0 cell, is the

single diode model H@. As shown in figre &?- the single diode model

consists of a crrent sorce connected to a shnt diode and resistor 2+ sh3 and

a series resistor 2+ s3.

Figure (:&% Single diode model of the P1 cell

The otpt crrent of the 0 cell can be written as H@$

&?&3

;here$

? I is the otpt crrent of the solar cell,

? I L is the photocrrent.

5


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? I D is the diode crrent.

? I sh is the crrent in the shnt resistance.

I D is gi!en by$

&?-3

;here$

? I os is the satration crrent,

? q is the electronic charge,

? V is the terminal !oltage of the solar cell,

? R s is the series resistance,

? A is the ideality factor,

? K is 'oltGmann#s gas constant, and

? T is the Bnction temperatre in )el!in.

Ish can also be sbstitted by$

&?53

'y sbstitting eqations 2&?-3 and 2&?53 in eqation 2&?&3$

&?73

8inally I os is gi!en by$

&?93

;here$

? I or $ the satration crrent at Tr .

? Tr: +eference Temperatre

? Ego: band?gap for Silicon.

7


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The main conclsion from the pre!ios eqations is that the main

factors go!erning the power generated by the 0 cell are$ the amont of

light that the cell is e"posed to, and the operating temperatre 2)3 of the cell.

4"posre to light is referred to as Irradiance which is defined by the

ratio of power 2;att3 per area nit 2m-3.

(0; Effects of Irradiance and Tem#erature on P1 cells

As noticed in the pre!ios section the main factors contribting to the

crrent generated by the 0 cell are the temperatre and irradiance. This is

clearly illstrated in figre &?5.

The photo?generated crrent is directly proportional to the irradiance

le!el, so an increment in the irradiation leads to a higher photo?generated

crrent. 6oreo!er, the short circit crrent is directly proportional to the

photo?generated crrentK therefore it is directly proportional to the irradiance

H@.

;hen the operating point is not the short circit, in which no power is

generated, the photo?generated crrent is also the main factor in the 0

crrent H@.

It shold be noted that !oltage flctations de to change in

irradiance. (an be neglected in practice H@.

9


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Figure (:6% 1:P curves of a P1 cell at different Tem#erature and Irradiances

Temperatre howe!er ad!ersely contribtes to the 0 cell crrent.

This is de to the natre of Silicon ?N Bnction. And ths can be annoying

fact, since solar light contains high energy particles and ltra!iolet 203

radiations that can directly heat the 0 cell.

The natre of meteorological conditions and shading 2incldingclods3. 6akes it challenging to draw the ma"imm generated power by the

cell throgh the load. Ths it is reqired that the cell at certain !oltage that

enables it to draw its ma"imm power H


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(07 Ma


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Figure (:;% 1:P curve of the P1 cell =ith MPP

The first assmption is based on the shnt crrent as e"plained in

eqation &?5, this crrent is !ery small and can be neglected H. This will

simplify the calclations needed to effecti!ely control the otpt crrent of

the 0 cell 2array3.

Figure (:7% Im##:1m## characteristics of the P1 cell >?@

The second assmption is based on the Boint effect of irradiance and

temperatre on the 0 cell. To e"plain this obser!e figre &?7 which shows


17/33

the relation between the 6 illstrated by the ble and green lines, and

both irradiance and temperatre represented by the arrows.

If the green lines are assmed to be absoltely !ertical, neglecting the

small de!iation in 06 de to irradiation change at a constant temperatre.

nder this assmption the ma"imm power point crrent I6 becomes

linearly proportional to the irradiation 4 according to the eqation H$

&?@3

;here k is a constant.

/ence, it can be generaliGed that the 6 is linearly related to the

irradiance at any gi!en temperatre.


18/33

+ha#ter &% P1 System euirements

&0( P1 system design #rocedureThe first task in designing a 0 system is to estimate the system#s

load. This is achie!ed by defining the power demand of all loads, the

nmber of hors sed per day, and the operating !oltage H.

8rom the load ampere?hors and the gi!en operating !oltage for each

load, the power demand is calclated. /ence, the natre of the load 2D( or

A(3 dictates the design of the in!erter. In the e"treme case where the load is

prely D(, no in!erter is needed.

Some designs may reqire batteries, in order to maintain a consistent

power spply. In general 0 systems can be categoriGed into two distinct

classes based on the natre of the load they spply, namely? grid connected

0 systems and stand?alone 0 systems.

+egardless of their type, al 0 systems share common component, as

shown in figre -?&

Figure &:)% major P1 systems com#onents >B@

&>


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&0& .rid:+onnected P1 systems

*rid?connected photo!oltaic systems are composed of 0 arrays

connected to the grid throgh a power conditioning nit and are designed to

operate in parallel with the electric tility grid H.

There are two general types of grid?connected 0 systems, based on

their role$ systems that assist the operation of the tility grid dring day

time. And ha!e no battery backp. These systems are often referred to as

grid?spporting systems.

The other type of systems is one with battery backp. And can keep

the load operating partially or entirely dring a tility otage. These systems

are sometimes called grid?forming 0 power systems H.

Figure &:C% grid:connected 8grid:forming9 P1 system =ith battery backu# >B@

The key to a sccessfl operation of 0 systems is the in!erter,

thogh it is the most comple" component. This relation has led the

researchers to de!elop and impro!e solid state power de!ices sch as

I*'T#s, 6OS84TS, microprocessors and ;6 controllers. In order to

frther increase the reliability and sstainability of 0 system H.

&&


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&06 Stand:alone P1 Systems

Stand?alone photo!oltaic systems are sally a tility power alternate.

They generally inclde solar charging modles, storage batteries, and

controls or reglators H as shown in 8igre 5?5.

Figure &:?%Stand:alone P1 system >B@

In many stand?alone 0 systems, batteries are sed for energy storage

as they may accont for p to 7>J of the o!erall stand?alone 0 system cost

o!er its lifetime H&&.

So the design of stand?alone 0 systems emphasiGes on sitable

battery technology 2Nickel?(admim$ Ni?(d C Deep?cycle lead?acid

batteries3 H&&.

The o!erall cost of a stand?alone 0 system can be redced with

proper battery?charging control techniqes, which achie!e high battery state

of charge and lifetime, nder continosly !arying atmospheric conditions

H&&.

&-


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+ha#ter 6% Simulation and esults

60( P1 +ell Model

The 0 system shown in figre 5?&, has been modeled sing6atlabCSimlink, which offers a rich en!ironment for modeling power

systems in real?time.

The model consists of inpt constants i.e. Irradiance and temperatre.

The 0 sbsystem contains the eqations necessary to obtain the !oltage?

crrent cr!es of the 0 system.

The 0 sbsystem takes an inpt !oltage which refers to the open

circit !oltage of the 0 cell and calclates the 0 cell crrent

corresponding to the temperatre?irradiance inpts

Figure 6:B% P1 cell Simulink model

The otpt of this model can be !isaliGed dring the simlation

throgh two scopes. And the data obtained can then be transferred to 6atlab

workspace for frther analysis and processing.

The eqations for obtaining the otpt crrent are shown in the abo!e

Simlink 0 cell model.

&5


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These eqations are based on Standard Test (ondition parameters

ST( H, which are related to real world !ales. The description of these

parameters can be seen in table 5?&.

arameter Description 0ale nitShort circit crrent at ST( 5.-9 A

Irradiance at the ST( &>>> ;Cm-

Open circit !oltage at ST( 7- 0

Temperatre at the ST( -9M-.>>>5 nit?less

0oltage coefficient with respect to temperatre change ?>.>>7 nit?less

0oltage of 6 at ST( 57 0

Table 6:(% ST+ constants values and their discri#tions >?@f& 23 is described by the following eqation$

25?3

8nction 89 23 calclates the new ma"imm power point crrent, as

e"pressed in the following eqation$

&7


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25?&&3

This is the primary otpt of the 0 sbsystem block, the other otpt

is the initial !oltage which can be sed to pertrb the 6, is gi!en by the

eqation 5?@$

25?&-3

The simlation was e"ected nmeros times for different !ales of

temperatre and irradiance, in order to obtain the 0 cell characteristic

cr!es as e"plained in chapter &. The figres below show the I0 and 0

cr!es of Irradiance and temperatres implemented in this simlation.

The otcome of the simlation sing the model described earlier can

be !isaliGed in the following figres.

8igres 5?-.&, 5?-.-, and 5?-.5 show the otpt I0 cr!es for the 0 cell

modle for a gi!en temperatre 2-.&9 )3 with Irradiances of 9>> )wCm-,

&>>>)wCm-, and ->>>)wCm- respecti!ely.

Figure 6:&0(% I1 +urve at 7''D=/m&

&9


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Figure 6:&0&% I1 +urve at ('''D=/m&

Figure 6:&06% I1 +urve at &''' D=/m&

&@


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8igres 5?5.&, 5?5.-, and 5?5.5 show the otpt I0 cr!es for the 0 cell

modle for a gi!en Irradiance 2&>>> )wCm-3 with temperatres of -.&9),

5-5.&9), and 57.&9) respecti!ely.

Figure 6:60(% I1 +urve at &B?0(7 D

Figure 6:60&% I1 +urve at 6&60(7 D

&


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Figure 6:606% I1 +urve at 6;?0(7 D

As mentioned in chapter &, the simlation reslts agrees with data

from the literatre, and confirms the theoretical relationships between

meteorological conditions and the 0 cell I?0 cr!es.

The abo!e simlation was done nder the following cases$

? The temperatre was fi"ed and the Irradiance was !aried.? The Irradiance was fi"ed and the temperatre was !aried.

In the first case, the figres show that as the Irradiance increases, the !ale

of the otpt crrent increases significantly, while the !ale of the otpt

!oltage increases slightly. The opposite reslts are obtained when the

Irradiance decreases 2slight decrease in 0oltage and significant decrease in

crrent3.

The second case is when the irradiance is fi"ed and the temperatre is

!aried, it can be seen that the otpt !oltage decreases and therefore the

power, as the temperatre increase, and !ice !ersa.

&


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As seen in the simlation model the otpt crrent is mltiplied with

the inpt open circit !oltage, to calclate e power of the cell and ths 0?

cr!es can also be obtained sing the model as shown in figres 5?7 and 5?9,

respecti!ely.

8igres 5?7.&, 5?7.-, 5?7.5 below show the reslting 0 cr!e of the

model at a gi!en temperatre2-.&9)3, with !arying Irradiances 29>>

)wCm-, &>>> )wCm-, and ->>> )wCm-3 respecti!ely.

Figure 6:;0(% P1 +urve at 7''D=/m&

&


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Figure 6:;0&% P1 +urve at (''' D=/m&

Figure 6:;06% P1 +urve at &''' D=/m&

8igres 5?9.&, 5?9.-, 5?9.5 below show the reslting 0 cr!e of the

model at a gi!en Irradiance2&>>> )wCm-3, with !arying Temperatre

2-.&9), 5-5.&9), and 57.&9)3 respecti!ely.

->


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Figure 6:70(% P1 +urve at &B?0(7 D

Figure 6:70&% P1 +urve at 6&60(7 D

-&


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Figure 6:70&% P1 +urve at 6&60(7 D

It can be seen from the abo!e 0 figres that at a certain temperatre, and

with the !ariation of Irradiance at the cell model inptK the ma"imm power

point increases significantly as the Irradiance increases and !ice !ersa, while

the open circit !oltage increase slightly as the Irradiance increases, and !ice

!ersa.

--


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8igres 5?9.&, 5?9.-, and 5?9.5 show the 0 figres for the modle at a

certain irradiance2&>>> )wCm-3 while the temperatre is !ariedK it can be

shown that an increase in temperatre cases both the 6 and the open

circit !oltage to decrease, while a decrease in temperatre increases the

!ales of the 6 and open circit !oltage.

-5


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+onclusion

The principle modeling of photo!oltaic modle based on 6AT1A'

en!ironment with different solar irradiations is presented. The simlation

reslts re!ealed that, the higher the solar irradiance the higher the otpt of

the 0?I and ?0 cr!es, and the lower the irradiance the lower the power

otpt.

(on!ersely, when temperatre increases the 0 cell otpt power will

degrade. And ths the operation of the 0 cell is e"tremely dependent on the

meteorological conditions at which it operates.

This dependency reqires special control mechanism to reglate and

ma"imiGe the otpt power of the 0 cellCarray. This is achie!ed by sing

proper 6T techniqes. As was pre!iosly discssed.

-7


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eferences&. $auer .ottfried 30 Lecture Notes in Physics: Photovoltaic Solar Energy

onversion. Oldenbrg $ Springer /eidelberg, ->&9. 0ol. >&. IS'N &&. p. &5>. IS'N$ ?&-?5->5@?9.

&>. Ismail $aharuddin $in0 Design An" Develo%#ent o$ 3ni%olar SP4!

S*itching Pulses $or Single Phase (ull,&ri"ge Inverter A%%lication. s.l. $

ni!ersiti Sains 6alaysia, ->>.

&&. Novel -attery charging regulation syste# $or %hotovoltaic a%%lications.

Doutroulis E0 and DalaitGakis D0 s.l. $ I444, ->>7. I44 roceedings.?

4lectric ower Applications. 0ols. &9&, No. -, pp. &&?&

Modified Version of Senior Project

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