COMPUTER MODELLING AND
SIMULATION OF SOLAR PHOTOVOLTAIC DEVICES AND SYSTEMS
by
ANIL KUMAR RAI
CENTRE FOR ENERGY STUDIES
Submitted
in fulfillment of the requirements of the degree of Doctor of Philosophy
to the
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INDIAN
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INDIAN INSTITUTE OF TECHNOLOGY, DELHI HAUZ KHAS, NEW DELHI-110016
AUGUST, 2007
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Dedicated to My Parents
CERTIFICATE
This is to certify that the thesis entitled "COMPUTER MODELLING AND SIMULATION OF SOLAR PHOTOVOLTAIC DEVICES AND SYSTEMS" being submitted by Anil Kumar Rai to the Centre for Energy Studies, Indian Institute of Technology, Delhi, India, is worthy consideration for the award of the degree of Doctor of Philosophy and is a record of the candidate's original bonafide research work carried out by him under our guidance and supervision. The research work contained in it has not been submitted in part or full, elsewhere for the award of any degree or diploma.
ro . S.C. Kaushik Professor
Centre for Energy Studies
Indian Institute of Technology, Delhi Hauz- Khas New Delhi
New Delhi-110016 India
Vt \ co, . SG, i lei Prof. N. D. Kaushika Director
Research and Development
Bharti Vidyapeeth College of Engineering A-4 Paschim Vihar, Rohtak Road
New Delhi-110063 India
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ACKNOWLEDGEMENTS
I express most sincere gratitude to my supervisor Prof. N. D. Kaushika for his keen involvement through this research work. It was next to impossible for me to accomplish this work without his valuable guidance. My sincere thanks are also due to Prof. S. C.
Kaushik for advice and valuable discussions. I would like to acknowledge with due respect the student research committee members for providing the useful comments and suggestions. Sincere thanks are also due to Prof. B. P. Singh and Prof. M. P. Dave and Prof. Bhim Singh for their useful comments and suggestions.
I also acknowledge with thanks to Prof. S. S. Sharma and Dr. Bhupal Singh for providing useful suggestions towards the completion of this thesis. I would like to thank my research colleagues Dr. A. Mishra, Dr. N.K. Gautam, Dr. P. K. Sharma, Dr. M. N.
Chakravarty, Dr. M. Chaubey, Dr. P. K. Bhardwaj, Mr. Ram Naresh Tripathy, Mr. Manoj Gupta and Mr. Amit Sharma for their support. I would like to acknowledge with thank to Mr. I. Budding, Mr. Subhash Gupta and Mrs. Purnima Rawat for their help towards successful completion of this thesis.
I would like to acknowledge with thank all fellow staff of IIT Delhi for their moral support towards a successful completion of this thesis
The continuous support from my wife and son Kumar Rishabh was a great inspiration.
I express my deep respects to Late Shri Basudeo Rai, Late Shri Lalbabu Rai and Mr.
Ashok Kumar Singh for their blessings.
Anil Kumar Rai
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ABSTRACT
This thesis addresses the problem of mismatch losses in solar photovoltaic (PV) systems to enable the optimum sizing of the system for improvement of reliability to serve the variable load. At the outset, an investigation of mismatch losses in solar photovoltaic cell networks (arrays) has been carried out. The mismatch losses can be due to variety of reasons such as manufacturer's tolerances in cell characteristics, environmental stresses and shadow problem. Formulations of fractional power loss in series and parallel strings due to manufacturer's tolerances in cell characteristics have been carried out. The string made of fresh and soiled cells have been considered. It is found that the fraction power loss would increase from 2 to 12 % with aging of solar cells. However, this fractional power loss can be reduced to 0.4 —2.4 % by an appropriate series paralleling.
Subsequently, fault tolerance for the electrical mismatches of an array has been investigated. It includes series-parallel, bridge-linked and partially cross ties configurations. The bridge-linked configuration turns out to be significantly superior to the series-parallel and partially cross ties configurations.
The output energy delivered from solar PV array to battery (load) may be maximized by using a maximum power point tracker. In this thesis an artificial neural network based maximum power point tracking controller has been developed. The controller uses the temperature and solar radiation as input variables and estimates the corresponding maximum power voltage and current values.
A knowledge base for the design of stand-alone solar photovoltaic systems corresponding to Indian region is developed. The approach involves combining both the site and array characteristics in a single parameter referred to as unit array output /
N
equivalent unit array output and expressing this composite parameter as a function of geographical co-ordinates. Owing to the multitude of options in configuration and capacity the design of photovoltaic system involves broad uniqueness. An expert engineer is therefore, necessary to design them. A solar PV design aid expert system based on above knowledgebase has been developed for mass media adaptation of solar photovoltaic technologies.
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1 6 6 7 7 8
9 11 14 TABLE OF CONTENTS
Page No.
CERTIFICATE ACKNOWLEDGE ABSTRACT
LIST OF FIGURES LIST OF TABLES NOMENCLATURE
CHAPTER 1 SOLAR PV SYSTEMS: A REVIEW 1.1 SOLAR PV SYSTEM COMPONENTS
1.2 FIELD EXPERIENCE
1.2.1 Manufacturer's Tolerance in Cell Characteristics 1.2.2 Environmental Stresses
1.2.3 Shadow Problem
1.3 FAULT TOLERANT CIRCUITRY FOR SOLAR PHOTOVOLTAIC ARRAYS
1.4 SOLAR PV SYSTEM DESIGN
1.5 EXPERT SYSTEM DESIGN AID FOR SOLAR PV SYSTEMS 1.6 SCOPE OF THE THESIS
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CHAPTER 2 AN INVESTIGATION OF MISMATCH LOSSES IN SOLAR PV CELL NETWORKS
2.1 MISMATCH LOSSES
2.2 FORMULATIONS OF FRACTIONAL POWER LOSS IN 18 SOLAR PV ARRAYS
2.2.1 Solar cell model 18
2.2.2 Fractional power loss 23
2.3 COMPUTATIONAL RESULTS AND DISCUSSION 24
CHAPTER 3 AN INVESTIGATION OF FAULT TOLERANT CIRCUITRY FOR SOLAR PHOTOVOLTAIC ARRAY
3.1 NONUNIFORM ILLUMINATION AND HOT SPOTS EFFECTS 34 3.2 EFFECT OF SHADING ON I-V CHARACTERISTICS OF 36
SOLAR CELL MODULE
3.3 FAULT TOLERANT STRATEGIES 38
3.3.1 Fault Tolerance By Redundancy At Subsystem Level 42 3.3.2 Fault Tolerance At Component Level 47 3.4 FIELD EXPRIENCES WITH BL ARRAY SOLAR PV SYSTEM 54
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CHAPTER 4 ANN BASED SIMULATION OF MAXIMUM POWER POINT TRACKER FOR SOLAR PV SYSTEM
4.1 MAXIMUM POWER POINT TRACKER 59
4.2 MODEL OF THE SOLAR PV ARRAY 61
4.3 MODEL AND TRAINING OF ANN TRACKER 66
4.4 MODEL OF CHOPPER AND CONTROLLER 69
4.5 SIMULATION OF MAXIMUM POWER POINT TRACKER 70 (CONTROLLER AND CHOPPER) USING SIMULINK
4.6 RESULTS AND DISCUSSION 75
CHAPTER 5 SOLAR PV SYSTEM DESIGN: A KNOWLEDGE BASE APPROACH
5.1 DESIGN APPROACH 80
5.2 MATHEMATICAL MODEL 80
5.2.1 Site parameter 81
5.2.2 EHFS and UAO 83
5.2.3 Optimum array tilt angle 84
5.2.4 Calculation of yearly daily mean value of Unit Array Output 84
5.3 KNOWLEDGE ENGINEERING 85
5.3.1 Solar PV system without battery storage 85 5.3.2 Solar PV system with battery storage 89
5.4 COMPUTATIONAL RESULTS: DEVELOPMENT OF 90
KNOWLEDGE BASE
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5.5 POSSIBLE VARIATION IN ITERATION 103 5.5.1 Changing the depth of discharge of the battery as in preceding results 103 5.5.2 Keeping DOD constant and SOC variable 113
CHAPTER 6 DEVELOPMENT OF SOLAR PV DESIGN AID EXPERT SYSTEM
6.1 EXPERT SYSTEM 120
6.2 ILLUSTRATIVE RESULTS 122
6.2.1 Solar PV system without battery storage 122 6.2.2 Solar PV system with battery storage for and and non and zone 123 6.3 WEB ACCESS TO SOLAR PV DESIGN AID EXPERT SYSTEM 125
CHAPTER 7 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS 130
BIBLIOGRAPHY 134
APPENDIX-1 144
APPENDIX-2 148
APPENDIX-3 157
LIST OF PUBLICATION BIODATA
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