B

B.E. PROJECT
ON
Title of thesis (Times New Roman, Bold, 22 font size)
Submitted by
ASHISH DIDHRA (438IC14)
AYUSH KUMAR (439IC14)
DEEPAK PRAKASH (448IC14)
GAURAV KUMAR(460IC14)
(In partial fulfillment of B.E. (Instrumentation and Control Engineering) degree
of University of Delhi
Under the Guidance of
Dr. BHAVNESH KUMAR and Dr. SK JHA

DIVISION OF INSTRUMENTATION AND CONTROL ENGINEERINGNETAJI SUBHAS INSTITUTE OF TECHNOL0GY
UNIVERSITY OF DELHI, DELHI

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Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
00Signature Signature Signature
Student Name1 Student Name 2Student Name 3
Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078

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Student Name1 Student Name 2Student Name 3
Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
00Signature Signature Signature
Student Name1 Student Name 2Student Name 3
Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078

DECLARATION
This is to certify that the project entitled, “project title here” by student name and student name is a record of bonafide work carried out by us, in the Division of Instrumentation and Control Engineering, Netaji Subhas Institute of Technology, University of Delhi, New Delhi, in partial fulfillment of requirements for the award of the degree of Bachelor of Engineering in Instrumentation and Control Engineering, University of Delhi in the academic year 20XX-20XX.

The results presented in this thesis are original and have not been submitted to any other university in any form for the award of any other degree.

-34925629285Signature Signature Signature
Student Name1 Student Name 2Student Name 3
Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
00Signature Signature Signature
Student Name1 Student Name 2Student Name 3
Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX Roll No. XXXX/IC/XX
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
CERTIFICATEThis is to certify that the project entitled, “project title” by student1 and student1 is a record of bonafide work carried out by them, in the Division of Instrumentation and Control Engineering, Netaji Subhas Institute of Technology, University of Delhi, New Delhi, under our supervision and guidance in partial fulfillment of requirements for the award of the degree of Bachelor of Engineering in Instrumentation and Control Engineering, University of Delhi in the academic year 20vv-20vv.

The results presented in this thesis are original and have not been submitted to any other university in any form for the award of any other degree.

-2025651019810Details of the supervisor1 Details of the supervisor 2
Designation Designation
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
00Details of the supervisor1 Details of the supervisor 2
Designation Designation
Instrumentation and Control Engineering Division
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
CERTIFICATEThis is to certify that the project entitled, “project title” by student1 and sstudent2 is a record of bonafide work carried out by them, in the division of Instrumentation and Control Engineering, Netaji Subhas Institute of Technology, University of Delhi, New Delhi, in partial fulfillment of requirements for the award of the degree of Bachelor of Technology in Instrumentation and Control Engineering, University of Delhi in the academic year 20XX-20XX.

Prof. XXXXXXXXXXXX
Head of the Division
Division of Instrumentation and Control Engineering
Netaji Subhas Institute of Technology (NSIT)
Azad Hind Fauj Marg
Sector-3, Dwarka, New Delhi
PIN – 110078
PLAGIARISM REPORT

ABSTRACTThis page is required for all graduate theses. An abstract is a short paragraph explaining the major points and conclusions of your thesis

LIST OF TABLES TOC h z “Table” c Table 1.1: Effect of Random PAGEREF _Toc359607030 h 1Table 2.1: Effect of Random PAGEREF _Toc359607031 h 1Table 3.1: Effect of Random PAGEREF _Toc359607032 h 1Table 4.1: Effect of Random PAGEREF _Toc359607033 h 1Table 5.1: Effect of Random PAGEREF _Toc359607034 h 1Table 6.1: Effect of Random PAGEREF _Toc359607035 h 1Table 7.1: Effect of Random PAGEREF _Toc359607036 h 1Table 8.1: Effect of Random PAGEREF _Toc359607037 h 1Table 9.1: Effect of Random PAGEREF _Toc359607038 h 1LIST OF FIGURES
TOC “Caption” c Figure 1.1: Label. PAGEREF _Toc359607167 h 1
Figure 1.2: Density of liquids peak. PAGEREF _Toc359607168 h 1
Figure 2.1: Label. PAGEREF _Toc359607169 h 1
Figure 2.2: Density of liquids peak. PAGEREF _Toc359607170 h 1
Figure 3.1: Label. PAGEREF _Toc359607171 h 1
Figure 3.2: Density of liquids peak. PAGEREF _Toc359607172 h 1
Figure 4.1: Label. PAGEREF _Toc359607173 h 1
Figure 4.2: Density of liquids peak. PAGEREF _Toc359607174 h 1
Figure 5.1: Label. PAGEREF _Toc359607175 h 1
Figure 5.2: Density of liquids peak. PAGEREF _Toc359607176 h 1
Figure 6.1: Label. PAGEREF _Toc359607177 h 1
Figure 6.2: Density of liquids peak. PAGEREF _Toc359607178 h 1
Figure 7.1: Label. PAGEREF _Toc359607179 h 1
Figure 7.2: Density of liquids peak. PAGEREF _Toc359607180 h 1
Figure 8.1: Label. PAGEREF _Toc359607181 h 1
Figure 8.2: Density of liquids peak. PAGEREF _Toc359607182 h 1
Figure 9.1: Label. PAGEREF _Toc359607183 h 1
Figure 9.2: Density of liquids peak. PAGEREF _Toc359607184 h 1

LIST OF ABBREVIATIONS AND SYMBOLSIf you do not have any symbols, abbreviations, or specific nomenclature in your thesis, you do not need to fill out this table.
Symbol Definition
? Frequency

INDEX OF EQUATIONSEquation Caption Page
Equation 1.1 PID control law 29
Equation 1.2 COG defuzzification method 63
Equation 1.3 PI control law 63

TABLE OF CONTENTS TOC h z “Heading 1,2,Heading 2,3,Heading 3,4,Heading 4,5,front matter heading style,1,Appendix Heading 1,2,Appendix Heading 3,4,Appendix Heading 2,3,Reference List Heading Style,2” DEDICATION PAGEREF _Toc356575605 h iACKNOWLEDGEMENTS PAGEREF _Toc356575606 h iDECLARATION PAGEREF _Toc356575607 h iCERTIFICATE PAGEREF _Toc356575608 h iCERTIFICATE PAGEREF _Toc356575609 h iABSTRACT PAGEREF _Toc356575610 h iLIST OF TABLES PAGEREF _Toc356575611 h iLIST OF FIGURES PAGEREF _Toc356575612 h iLIST OF ABBREVIATIONS AND SYMBOLS PAGEREF _Toc356575613 h iINDEX OF EQUATIONS PAGEREF _Toc356575614 h iTABLE OF CONTENTS PAGEREF _Toc356575615 h iREFERENCES PAGEREF _Toc356575616 h 1
(Right click on the Table of Contents and choose “Update Field”. All text formatted with the styles “Heading 1”, “Heading 2”, “Heading 3”, “Heading 4”, will be included. These 2 liremoved after final formatting.)

Solar Cell
Introduction
With the fossil fuels exhausting at a tremendous rate and the air pollution level rising at alarming rate, it is high time to switch to a cleaner and more easily available source of energy. Sun is the ultimate source of energy on the earth, harvesting energy from sun is an alternative option to fossil fuels. It is clean, easily available and is never ending. A PV cell is a device which can covert the energy from the sun to electricity. These PV cells are discussed in this chapter.

A PV cell or photovoltaic cell is a specialized semiconductor diode electronic device which
converts light energy into electrical energy by using various chemical and physical phenomena.
These type of cells are technically very similar to the photoelectric cells as both change their
electrical characteristics, such as current, voltage or resistance when exposed to light.

A photovoltaic cell is also known as a solar cell.

Photovoltaic cells does not essentially require sunlight to convert light into electrical energy; in
fact, an artificial source of light can also be converted into electrical energy. Some photovoltaic
cells also convert infrared radiation or ultraviolet radiation into DC electricity. The steps
involved in producing electrical energy include absorption of light by the electrons of the
material (usually silicon), which creates an electron-hole pair. This will lead to separate the
positively and negatively charged particles. The separated charges produces potential in an
external circuit and current is produced hence electrical energy is produced. Photovoltaic cells
are used in infrared detectors, light intensity calculators, solar fans, solar heater and solar panels
for producing solar power for homes, offices or industries. A PV module consists of hundreds or
thousands of photovoltaic cells that are mounted together in the form of a large cell module.

The first PV cells was made by combining or doping silicon with other elements to alter the
behavior of electrons or holes (electron absences within atoms). Materials as copper indium
diselenide (CIS), cadmium telluride (CdTe), and gallium arsenide (GaAs), are developed so that
they can be used in PV cells. There are two basic types of semiconductor material, positive (or P
type) and negative (or N type). In a PV cell, flat pieces of these materials are put together, and
the physical boundary between them is termed as P-N junction. The device is constructed in such
a way that the junction can be exposed to visible light, IR or UV. When such radiation strikes
the P-N junction, it produces a voltage difference between the P type and N type materials.

Electrodes connected to the semiconductor layers allow the current to be drawn from the device.

Large sets of PV cells are connected together to form solar modules, arrays, or panels.

Working
The solar cells that we see on calculators and satellites are also called photovoltaic or PV cells,
which as the name suggests (photo meaning “light” and voltaic meaning “electricity”), It converts sunlight directly into electricity. A module is a group of cells connected electrically and put into a frame (more commonly known as a solar panel), which can then be grouped into larger solar arrays.

Photovoltaic cells are made of semiconductors out of which silicon is the most commonly used
material. Silicon has some special chemical properties especially in its crystalline form.

An atom of silicon has 14 electrons that are arranged in three different shells. The first two shells
holds two and eight electrons respectively and are completely full. The outer shell is having just
four electrons. A silicon atom will always tries to fill up its last shell and in doing so it will end
up with sharing electrons with four nearby atoms. It’s like each atom holds hands with its
neighbors except that in this case each atom has four hands joined to four neighbors. This
arrangement forms the crystalline structure, and that structure turns out to be important to this
type of PV cell. Basically when light strikes a cell a certain portion of cell will get absorbed
within the semiconductor material. The energy of the absorbed light is transferred to the
semiconductor. The energy knocks electrons loose, allowing electrons to flow freely.

Fig. 1.1 working of a PV cell
PV cells have one or more electric field that force electrons that are freed up by light absorption
to flow in a certain direction. The flow of electrons constitutes a current and metal contacts are
arranged on the top and bottom of the PV cell in such a way that we can draw the current for
external use. Now this can be used as any other source of electricity. This current together with
the cell’s voltage defines the power or wattage that the PV cell will produce. Figure 1.1 demonstrates the working of a photo voltaic cell.

Fig. 1.2 PV and VI curves of a photo voltaic cell.

1.3 Electrical characteristics of a PV cell.

The figure above shows the PV and IV curve of a typical silicon PV cell. The power obtained by a PV cell is the product of current and the voltage. The curve obtained by multiplying I and V from short circuit conditions to open circuit conditions results in the PV (power-voltage) curve.

When the positive and negative terminals of the cell are connected together, the voltage across the cell reaches its minimum, i.e., zero but the current reaches its maximum value called the short circuit current (Isc). When the cell is not connected to any load the current cannot flow and becomes zero but the voltage reaches its maximum value called the open circuit voltage (Voc). The IV curve ranges from Isc to Voc , but the power obtained at both these points is zero, but there has to be point at which the power reaches its maximum value, this point is called the MPP (maximum power point ) and the current and voltage at this point are called Impp and Vmpp respectively.

MPP is point where the power supplied by the PV cell/ array is the maximum when it is connected to a load. MPP is generally located at the bend of the PV curve.

P-N Fabrication
Silicon is the material by which the transistors (tiny switches) in microchips were made and solar cells work in a similar way. Silicon is a semiconductor type material. Some materials especially metals allow electricity to pass through them very easily so they are called conductors. Other materials, such as plastics and wood are termed as insulators as they don’t really let electricity flow through them at all. Semiconductors (like silicon) are neither conductors nor insulators they don’t normally conduct electricity but under certain circumstances we can make them to conduct.

A PV cell consists of two layers of silicon that have been specially treated or doped so they will allow electricity to flow through them. The lower layer is doped in such a way that it has too few electrons which is called p-type or positive-type silicon (electrons are negatively charged and this layer has too few of them). The upper layer is doped in the opposite way to give it too many electrons. It’s called n-type or negative-type silicon.
We place an n-type silicon layer on p-type silicon layer a potential barrier will get created at the junction of the two materials (the border where the two kinds of silicon meet up). No electrons can cross the barrier so, even if we connect this silicon sandwich to a flashlight, no current will flow and hence the bulb will not light up. But if we expose sandwich to the light something remarkable happens. We can think of the light as a stream of large number of light particles called photons. As photons enters our sandwich they transmit their energy to the atoms in the silicon. The energy extracts electrons of the p-type so that electrons jump across the barrier to the n-type and flow out around the circuit. The more will be the light the more electrons jump out and the more current flows.

Types of PV cells
There are several types of PV solar cell available in the market that can be used based on the needs, a few of them are discussed here.
Monocrystalline solar cell
One single cylindrical crystals of silicon is used to make monocrystalline cell. This is the most effective photovoltaic innovation, commonly changing over around 15% of the sun’s vitality into power. The assembling procedure required to create monocrystalline silicon is convoluted, bringing about somewhat higher expenses than different advancements
1.4.2 Polycrystalline Silicon PV panels
Additionally some of the time known as multicrystalline cells, polycrystalline silicon cells are produced using cells cut from an ingot of liquefied and recrystallised silicon. The ingots are then observed cut into thin wafers and gathered into finish cells. They are less expensive to develop than monocrystalline cells, because of the more straight forward assembling process, however they have a tendency to be somewhat less productive, with normal efficiencies of around 12%.

Thick-film silicon PV panels
This is a variation on multicrystalline innovation where the silicon is stored in a constant procedure onto a base material giving a fine grained, shimmering appearance. Like all crystalline PV, it is regularly exemplified in a straightforward protecting polymer with a safety glass cover and afterward bound into a metal confined module.

1.4.4 Amorphous silicon PV panels
Formless silicon cells are made by saving silicon in a thin homogenous layer onto a substrate instead of making an unbending precious stone structure. As nebulous silicon retains light more viably than crystalline silicon, the cells can be more slender – henceforth its elective name of ‘thin film’ PV. Shapeless silicon can be saved on an extensive variety of substrates, both inflexible and adaptable, which makes it perfect for bended surfaces or holding straight forwardly onto roofing materials. This innovation is, in any case, less proficient than crystalline silicon, with run of the mill efficiencies of around 6%, however it has a tendency to be less demanding and less expensive to deliver. In the event that rooftop space isn’t confined, a shapeless item can be a decent choice. In any case, if the most extreme yield per square meter is required, specifiers ought to pick a crystalline innovation.

1.5 Applications
1.5.1 Utility Scale Power
Expansive scale photovoltaic power plants, comprising of numerous PV panels/cells introduced together. Utilities can assemble PV plants considerably more rapidly than they can manufacture ordinary power plants on the grounds that the exhibits themselves are anything but difficult to introduce and associate together electrically. Utilities can find PV plants where they are most required in the matrix in light of the fact that siting PV exhibits is considerably simpler than siting a traditional power plant. What’s more, not at all like ordinary power plants, PV plants can be extended incrementally as request increments. At long last, PV control plants expend no fuel and create no air or water contamination while they quietly produce power.
Shockingly, PV plants have a few attributes that have impeded their utilization by utilities. Under current utility, PV-produced power still costs extensively more than power created by ordinary plants, and administrative offices require most utilities to supply power for the least money cost. Besides, photovoltaic frameworks create control just amid sunlight hours and their yield changes with the climate. Utility organizers should thusly treat a PV control plant uniquely in contrast to they would treat a traditional plant.

1.5.2 Hybrid power system
Mixture frameworks consolidate various power generation and capacity pieces to take care of the vitality demand of a given office or group. Notwithstanding PV, motor generators, wind generators, little hydro plants, and some other wellspring of electrical vitality can be added as expected to meet vitality requests and fit the neighborhood land and worldly qualities. These frameworks are perfect for remote applications, for example, correspondences stations, army bases, and provincial towns.
Basic to building up a half breed electric framework is knowing the vitality request to be met and the assets accessible. Vitality organizers subsequently should think about the sun powered vitality, wind, and other potential assets at a specific area, notwithstanding the arranged vitality utilize. This will enable them to outline a mixture framework that best takes care of the requests of the office or group.

***

Partial Shading
Partial shading
Whenever we install PV array in our home or office, there are certain things which need to be
taken care of such as if there is partial shading or if there will be any partial shading in near
future. Shading can occur due to a grown tree or a building which may be built after our setup is
completed.
These are two types of partial shading:
Avoidable Partial Shading
Unavoidable Partial Shading
Avoidable Partial Shading
Partial shading which is caused by trees or buildings or other things which are feasible to avoid
are known as avoidable partial shading. These are called as avoidable partial shading as we can
install our setup with a proper planning if there would be any trees or buildings in the way and
we can place our setup accordingly.

Unavoidable Partial Shading
Partial shading which is caused by moving clouds, flying birds or flying airplanes is known as
unavoidable partial shading. This is called so as we have no control over these things. We can’t
control clouds, birds or airplanes and thus we can’t avoid these things.

So, no matter what we do partial shading is going to occur and this is going to affect our power
generation. As we can’t do anything about clouds passing above our PV Array but what we can do is to see if any tree will grow to do some harm to our panel by shading our system and if we come across such thing then we have to avoid it by choosing place of setup elsewhere.

Fig. 2.1 describing the shading and partial shading conditions
Effects of Partial shading
When we are dealing with large number of PV arrays then it is possible that it may come under
partial shading; avoidable or unavoidable and this can decrease our power generation to a large
extent as the area of the array which is partially shaded will generate very less power and this
effect does not just depend on the area of partially shaded region but depends on the location of
this region on the array and array configuration too. Thus, we can see that partial shading is very
harmful for our setup as it can decrease our power generation to a large extent so we have to look
for a remedy to this problem so for this purpose we use bypass diode.

Fig. 2.2 a solar panel with partial shading
Bypass Diode
Bypass diode is nothing but a diode which is used in parallel with our PV cell or group of cells in
backward condition such that it can bypass our current in case there is partial shading in that cell.

Thus, a bypass diode prevents the power loss to a great extent.

Fig. 2.2 illustrating working of a bypass diode
Configurations
Introduction
The PV cells are interconnected to form large modules, they can be interconnected in series and parallel, the interconnections greatly influence the overall performance of the modules or PV arrays. Different interconnections are made to optimize the power output under various environment conditions and requirements. The cells can be interconnected to form different configurations, a few of those configurations are studied in this chapter.

Series Configuration
In this configuration the photo voltaic cells are connected in series with each other to form one single string of PV cells. This is probably the easiest configuration but it has several drawbacks when operating under partially shaded conditions. When the shading intensity on a cell of the series string is high the bypass diode becomes active and that cell is bypassed from the string, the overall power of the string reduces but this cannot be avoided in any of the configuration. But in the case of partial shading or when the shade intensity is not high enough to activate the bypass diode the cell will impose current limitation on the overall string, and the other non-shaded cells will be working far below their maximum power points.

Fig. 3.1 Series Configuration Fig. 3.2 Parallel Configuration
Parallel Configuration
Parallel configuration consists of parallel connected string of PV panel, fig 2.2. In a parallel configuration during shading there is no current limitations and the variation in voltage is also very less. Thus in parallel connection operation panels operate at their maximum power points and hence ensuring maximum power extraction. But there is one problem with the parallel configuration is that the total string current will be the sum of individual cell current, so the total current is way too large thus it cannot be used everywhere.

SP Configuration
SP configuration stands for Series Parallel configuration which consists of parallel connected series strings of PV cells, figure 2.3. This configuration yields better results in partial shading condition then series configuration and overall current is also limited but since the series connection is effected more by partial shading, this configuration results in lesser utilization factor.

Fig. 3.3 SP Configuration Fig. 3.4 TCT Configuration
TCT Configuration
TCT configuration stands for Total Cross Tied, it is composed of serially connected paralleled PV panels. This configuration provides better results than series configuration and current is also limited. TCT and SP configurations are widely used to tackle partial shading effects.
PV and IV curves
PV and IV curves for different reconfigurations under no-shading conditions are for 3×3 PV arrays are shown in the figures below.

right34800 (a)
right34544000
(b)
Fig PV curve for series configuration

right12258300
right33591500

right25717500
Effects of Partial Shading on Different Configurations
3.1 Partial shading conditions
To study the effects of partial shading on different configuration schemes, three different shading conditions, fig , are implemented on different configurations and their results are observed and studied with the help of Simulink.

(b) (c)
Fig Partial shading Conditions
Parallel
Simulink model

I-V and P-V curves
IV and PV curves under the three partial shading conditions are as follows
right35369500
right358968300Fig I-V curve for (a),(b) and (c)
Fig
SP Configuration
Simulink Model

right3336960I-V and P-V curve
right367780200case a and c

right5600..

right34734500
right35369500
RECONFIGURATION
Introduction
There is a difference between the actual power harvested and power that can be harvested, the
difference is more in the case of partial shading. More power can be harvested by improving the
V-P characteristics and in turn the MPP of the PV array. This improvement can be done by
altering the location of the shaded panels, varying interconnection schemes in accordance with
the prevailing shading conditions.

Reconfigurations can be done either dynamically or it can be static.

1.2 Dynamic Reconfiguration
PV system is dynamically altered by
Switching the interconnection scheme that yields more power.

Distributing shade intensity to avoid mismatch.

Adjusting number of panels in series / parallel to equalize row current.

1.2.1 Electrical Array Reconfiguration (EAR)
EAR was initially utilized to optimize the performance of the volumetric pump. Switches are used
to reconfigure the panels connected to them, reconfiguration occurs when an EAR controller
senses the irradiation levels. The reconfiguration algorithm determines the interconnection and
actuates appropriate switches in the switching matrix. EAR can be applied to S, P, SP, TCT, HC
and BL.

Fig. 1.1 Electrical Array Reconfiguration
Advantages of EAR
Real time adaptation to the external condition (partial shading).

Self-capacitive for real time adaptation (no monitoring is required).

Drawbacks of EAR
The number of switches required to alter the interconnections increases with the array size.

Overall size, cost and complexity of the system increases.

1.2.2 Adaptive Array Reconfiguration (AAR)
In this type of reconfiguration there are two groups of PV arrays, fixed bank and adaptive bank.
The fixed bank is configured in TCT and remains static. The adaptive bank is equally connected
to each of the row in fixed bank under normal or uniform irradiation condition, through a switching
matrix. Under non uniform irradiation conditions or partial shading the number of panels that are
to be connected to each row of the fixed bank is determined and switched dynamically according
to the prevailing shading condition. The rows which are more affected by the shading is given
more share of the adaptive bank so that the output produced by each of the rows remains similar
and current mismatch in each row can be avoided, therefore giving a single peak on VP curve.
AAR requires an intelligent algorithm to dynamically control the switching matrix.

Fig. 1.2 Adaptive Array Reconfiguration
1.2.3 Irradiation equivalence by relocation of panels
This relocation technique is based on the principle of irradiation equivalence, that is, the PV panels
are relocated to other rows such that there is no current limitation imposed by any serial string of
parallel connected cells/panels. Each row contains same numbers of cell before and after the
relocation, and the number of panels in series and in parallel also remains same.

But changing of physical location of panel/cell dynamically is a difficult task, so this is mimicked
by altering the interconnections of the panels. Still the number of possible arrangements even for
a very small array is very large and hence this configuration technique is not a popular choice.

Fig. 1.3 Arrangement in a Repositioning scheme
1.3 Static reconfiguration techniques
The interconnections are not altered dynamically but the physical location of the panel is planned
strategically. The objective is to disperse the shading effect almost equally over the array. Since
there no requirement of switches and associated auxiliary circuits, the implementation and control
strategies are simpler as compared to that of the dynamic reconfiguration. The Sudoku puzzle
pattern and magic square pattern are employed to decide the location of the solar cells within the
array and the interconnection and wiring is done thereafter.

1.3.1 Sudoku puzzle pattern
In Sudoku pattern the panels / cells which belong to a particular row are physically placed at
different locations in each of the other row. This arrangement results in the reduced mismatch
losses. The panels are not arranged dynamically by sensing the prevailing shading conditions and
does not require any intelligent algorithm, the arrangement of panels are in accordance with
Sudoku puzzle patterns.

Suppose we have a M x M panels (m rows each having m number of cells), each physical row is
arranged like a Sudoku, just like in Sudoku all the numbers put in a row are unique, each physical
row will have a panel from all the internally connected row, there will be no two panels which are
electrically connected to the same row put together in a physical row. In a TCT connection there
will be mismatch in all the cases other than vertical and diagonal partial shading conditions,
Sudoku pattern ensures that the mismatch is reduced in all the other partial shading cases.

For Sudoku arrangement all the cells/ panels are identified with two digits (row and column
position). The left digit corresponds to the row and the right digit corresponds to the column.

(b)

(c) (d)
Fig. 1.4 (a)Conventional TCT arrangement, (b)Sudoku arrangement, (c)Shade dispersion on Sudoku arrangement, (d) TCT interconnection

The arrangement of cells in a 3×3 array in conventional and Sudoku pattern are shown in figure
1.4, the Sudoku arrangement is subjected to partial shading conditions and following results are
obtained.

1.3.2 Magic Square Pattern
This pattern quite similar to Sudoku pattern, both are static reconfiguration techniques but for the
fact that it uses a MxM magic square. All the panels are identified sequentially a magic and then
rearranged to form a magic square. A magic square is a square grid filled with distinct numbers
such that the sum of each row, column and diagonal is equal.

(b)

(c) (d)
Fig. 1.5 (a) conventional TCT connection, (b) magic square arrangement, (c) shade dispersion on magic square pattern, (d) TCT interconnection

1.4
Improved Sudoku Arrangement
There are many algorithm that have been proposed to determine the position of cells/panels with
in the array. These algorithms calculate the distance or the shifting displacement, d, between two
adjacent panels. We have studied one such algorithm and implemented it.
This improved Sudoku arrangement relies on the fact that output is maximum when the row
currents are matched in a TCT configuration.
To ensure that the shade is uniformly distributed the row that belong to a row should not be placed
next to each other and should be separated by a minimum distance governed by the size of the
array.

The location of panels in this proposed arrangement is determined by
Yij = Xkj where i=1,2,3….m
The row index k = (i+(j-1)*d),
where d=ceil (under root (m))
if k<m, then k=k
else k=k-m
if manipulation a k results in a value of k that already exists then add an offset value of 1.

For a 3X3 PV array the m=3, therefore d= ceil(under root(3))=2.

The first index in the first row is taken to be 1. The second index of first row is 3(1+2), obtained
by adding d to the preceding index, the third index of the first row is 5(3+2), since 5 is greater than
m, m(3) is subtracted by the index value, so the third index value is 2(5-3). Similarly index values
of remaining rows are determined. The resulting arrangement is shown in the figure 1.5.

(b)

(d)
Fig. 1.5 (a) conventional TCT connection, (b) proposed Sudoku arrangement, (c) shade dispersion on proposed pattern, (d) TCT interconnection

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Conclusion
The working of solar panel, partial shading and its effects on output of various interconnection schemes have been dealt with in this study. Various techniques for reducing the effect of partial shading have also been studied and dominant techniques to reduce the effect of partial shading is reviewed and it is inferred that the dynamic reconfiguration techniques requires sensors, switches and intelligent switching control algorithms. The addition of these requirements increases the overall cost and complexity of the system and is not very much suitable for large scale installation.
Static configurations on the other side does not require any additional equipment, the panels are arranged intelligently so as to minimize the effect of partial shading by dispersing the shading / partial shading effectively all over the array. Among the various Sudoku optimization technique one has been studied and implemented and better results are obtained in more number of cases than in simple Sudoku.

REFERENCESReferences should be written by strictly adhering to the format in the examples given below.
G. H. Cohen, G. A. Coon, “Theoretical Considerations of Retarded Control,” Transactions on American Society of Mechanical Engineers, Vol. 75, No 20, pp. 827-830, 1953.

H.A. Malki, H. Li, G. Chen, “New design and stability analysis of fuzzy proportional-derivative control systems,” IEEE Transaction on Fuzzy Systems, Vol. 2, No., pp. 245-254, 1994.

R. Eberhart, J.Kennedy, “Particle swarm optimization,” Proceedings of the sixth International Symposium on Micro Machine and Human Science, Japan: Nagoya, pp. 39-73, 1995.

Mitsua Gen, Runewi Chang, “Genetic Algorithm and Engineering Optimization”, John Wiley & Sons, New York, 2000, Chapter 1.

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