UNIVERSITY ©F BBWITUWA, 9H LAOtt 11 D E V E L O P M E N T OF A G R I D C O N N E C T E D S O L A R P H O T O V O L T I C S Y S T E M Kotudurage Shanaka Asanga (07/8405) Degree of Master of Science University of Moratuwa iiii i minimi 102533 Department of Electrical Engineering ~ \> , . / / October 2011 University of Moratuwa Sri Lanka *W 102533 D E V E L O P M E N T OF A G R I D C O N N E C T E D S O L A R P H O T O V O L T I C S Y S T E M Kotudurage Shanaka Asanga (07/8405) Dissertation submitted in partial fulfillment of the requirements for the degree Master of Science Department of Electrical Engineering University of Moratuwa Sri Lanka October 2011 DECLARATION I declare that this is my own work and this dissertation does not incorporate without acknowledgement any material previously submitted for a Degree or Diploma in any other University or institute of higher learning and to the best of my knowledge and belief it does not contain any material previously published or written by another person except where the acknowledgement is made in the text. Also, I hereby grant to University of Moratuwa the non-exclusive right to reproduce and distribute my dissertation, in whole or in part in print, electronic or other medium. I retain the right to use this content in whole or part in future works (such as articles or books). The above candidate has carried out research for the Masters Dissertation under my supervision. Signature of the supervisor: Date iii Acknowledgement Thanks are due first to my supervisor, Dr.J.P.Karunadasa, for his great insights, perspectives, guidance and sense of humor. My sincere thanks go to the officers in Post Graduate Office, Faculty of Engineering, and University of Moratuwa, Sri Lanka for helping in various ways to complete my academic works in time with excellent cooperation and guidance. Sincere gratitude is also extended to the people who serve in the Department of Electrical Engineering office. I would like to extend my sincere gratitude to the Management and whole staff of AES Kelanitissa (PVT) Ltd for the provision of comprehensive support during the project development phase. Also I would like to give my thanks to my wife Priyanka, daughters Dihini and Mihini, also to my parents ,my sister and brother in-law for encouraging and supporting me. Lastly, I should thank many individuals, friends and colleagues who have not been mentioned here personally in making this educational process a success. May be I could not have made it without your support. iv Abstract This study and development are focused about an integration of a solar photovoltaic (PV) system to an existing power plant located in Colombo Sri Lanka. The combined cycle power plant related to the project consists of many easily identifiable resources for the development of a solar project. Survey to find out available resources, ways of integrating the selected resources to optimize the project outcome, best way to utilize the solar energy and finding out the feasibility of implementing the project are the objective behind the project development. The project identifies a grid connected solar PV system with a single axis tracking as the best way to integrate solar PV energy to an existing power plant. The areas of study and design are related to solar panels and the structural frame work, sun tracking system, tracker drive mechanism, power conversion and power evacuation system. The project components selection criteria developed in this project are based on the preliminary studies and surveys. Comparison made for deferent types of solar cells based on their reliability, cost & efficiency. Also surveys were done about gains, regulations, quality checks, safety and environmental aspects related to project components. Upon finalizing the basic project configuration, sizing of the systems carried out in a logical criterion prior to the detailed design stages. Comprehensive design carried out for the control module and drive mechanism of solar tracker which demonstrates the flexibility of existing plant control system. Design of structural framework is used to find cost components relevant to the balance of system and to find out the impact of loading the building roof with solar PV components. Cost benefit analysis carried out against three different options of energy dispatch to meet the conclusions. As an outcome following conclusions have been met, • By effective utilization of existing resources available at a power plant simple pay back (SPB) period of a solar PV system of 106 k W capacity could be brought down to 9-10 years . • A single axis tracking system could further reduce the SPB period of a solar PV system. • It is more beneficial to export solar PV energy separately to the grid during the cases where thermal energy production cost is cheaper than Rs.20/= to further bring down SPB period. This is possible by introducing a switching signal from DCS for smooth change over between separate power feeding and station power feeding based on online energy unit cost comparison. • Design, construction and commissioning of Solar PV system with a thermal power plant at initial stages in parallel with main project could avoid wastages of resources. The concepts and design criteria used at different phases of this project development could be useful for direct application or with appropriate modifications to incorporate with solar PV project developments. vi TABLE OF CONTENTS Declaration of the candidate & Supervisor iii Abstract iv Acknowledgements v Table of content vii List of Figures x List of Tables xii List of abbreviations xiv List of Appendices xvi 1. Introduction 1.1 Background and Preliminary Survey 1 1.2 Energy demand by plant Auxiliaries 2 1.3 Motivation 2 1.4 Achievement in brief 3 2. Problem Statement 2.1 Identification of the Problem 4 2.2 Objectives of the Study 4 2.3 Importance of the Study 5 3. Proposed Solution 3.1 Conceiving Features of a Relevant Solution 6 3.2 Methods and Techniques 6 4. Survey and Analysis 4.1 Survey for solar photovoltaic energy availability at site. 7 4.2 Market survey and Solar panel selection. 8 4.2.1 Crystalline Silicon Solar Cells 8 4.2.2 Thin Film Technologies 9 4.2.3 Space and Concentrator Cells 12 4.2.4 Organic and Dye Sensitized Cells 13 4.3 PV Module Qualification tests 14 4.4 Solar panel selection against site conditions 15 4.4.1 Project frame work, factors to be considered and available 15 Resources 4.4.2 Panel selection 18 4.5 Basis for selection of Grid connected system 18 4.6 Basis for selection of tracking system 19 4.7 Safety, protection and Environmental aspects 19 4.7.1 Safety, protection and Environmental aspects of PV modules 20 vii 4.7.2 Safety, protection and Environmental aspects of tracking system 4.7.3 Safety, protection and Environmental aspects of Power circuit Equipments 22 24 5. System development 5.1 Sizing of Solar Panels 28 5.2 Sizing of Invertors and power circuit components 29 5.3 Sizing of structural frame work 31 5.3.1 Design of Shaft size 33 5.3.2 Supports and bearings for rods/shafts 40 5.4 Sizing of Manual Tilting frame work 43 5.5 Design of tracking system 44 5.5.1 Few Tracking options which can be integrated with DCS 44 5.5.1.1 Chronological/Timer based system 44 5.5.1.2. Solar intensity based system 45 5.5.1.3. Function based system 45 5.5.1.4. Heliostat Principle 45 5.5.2 Selection of best tracking option and development of Basic model 45 5.5.3 Solar tracker design 46 5.5.3.1 Different conditions effecting solar intensity and panel Orientation 47 5.5.3.2 Process flow table of the Tracking system 47 5.5.3.3 Potential divider for CdS array signal detection 48 5.5.3.4 Basic design in DCS for the control 49 5.5.3.5 Design considerations for CdS array. 50 5.5.3.6 Conditional logics and the switching of either fixed set point or tracking 51 5.5.3.7 Details of Function codes (used for the developments of DCS Logics and process control scheme). 51 5.6.1 DCS Logic diagram for inputs 53 5.6.2 DCS Logic diagram for selection of output from 3 transmitters 54 5.6.3 DCS Logic diagram for generation of position signals and switching signal with time delay for default or tracking set point 55 5.6.4 DCS Logic diagram for the selector for default or tracking mode and solar panel position control 56 5.6.5 DCS Logic diagram for output signal for Solar panel position control actuator. 57 5.7 Design of balance of system of the unit 58 6. Financial benefits analysis 6.1 Expected energy balance 64 6.2 Project cost 64 6.3 Cost benefit analysis for the implementation of the project 67 6.4 Cost benefit analysis for the implementation of tracking system 69 6.5 Cost benefit analysis for the implementation without tracking system 69 V l l l 7. Application of the Proposed Method 7.1 Applications 7.2 Implementation of the proposed systems 8. Concluding Remarks and Further Developments 8.1 Conclusions, Remarks and Discussion 8.2 Recommendations for Future Research/ Studies 9. References 10. List of Appendices List of Figures Figure 4.1 Solar resource potential map of Sri Lanka Developed by NREL (USA) 07 Figure 4.2 Connection Schematic diagram for grid connected PV system 20 Figure 4.3 Safety requirements of power circuit 24 Figure 4.4 Energy metering arrangement of Grid connected PV system 26 Figure 5.1 Front elevation of panel mounting frame 31 Figure 5.2 Cross section and dimensions of L iron bars 32 Figure 5.3 Bending moment diagram for a panel row (Case -1) 34 Figure 5.4 Member detailed forces (Case -1) 35 Figure 5.5 Bending moment diagram for a panel row (Case -2) 37 Figure 5.6 Member detailed forces (Case -2) 37 Figure 5.7 Radial loads applied on bearings (Case 1) 41 Figure 5.8 Radial loads applied on bearings (Case 2) 42 Figure 5.9 Bearing selection guide line (SKF) 43 Figure 5.10 Basic Model of Solar tracker 46 Figure 5.11 Potential divider for CdS cell signal detection 48 Figure 5.12 Basic design in DCS for the control 49 Figure 5.13 DCS Logic diagram for input signals 53 Figure 5.14 DCS Logic diagram for selection of output from 3 transmitters 54 Figure 5.15 DCS Logic diagram for generation of position signals and switching 55 Signal with time delay for default or tracking set point Figure 5.16 DCS Logic diagram for the selector for default or tracking mode and 56 solar panel position control Figure 5.17 DCS Logic diagram for output signal for Solar panel position 57 control actuator Figure 5.18 Panel orientation morning to noon 59 Figure 5.19 Panel orientation Afternoon 60 Figure 5.20 Panel orientation noon to evening 61 Figure 5.21 Modified application of Scotch Yoke Mechanism 62 Figure 5.22 Pneumatic valve / actuator operated by a control signal using I to P converter and P to P positioner 63 Figure A1 Function Code 132 75 Figure A2 Function Code 9 77 Figure A3 Function Code 2 78 Figure A4 Function Code 12 79 Figure A5 Function Code 37 80 Figure A6 Function Code 30 81 Figure A7 Function Code 65 82 Figure A8 Function Code 156 83 Figure A9 Function Code 80 85 Figure A10 Function Code 33 90 Figure Al l Function Code 8 90 x 4 Page Figure A12 Function Code 1 91 Figure A13 Function Code 10 92 Figure A14 Function Code 11 93 Figure Al5 Function Code 35 94 Figure Al6 Function Code 110 95 Figure Al7 Function Code 129 96 Figure Al 8 Function Code 69 99 Figure Al9 Function Code 39 100 Figure A20 Function Code 115 101 Figure A21 Function Code 16 102 Figure A22 Function Code 40 103 Figure A23 Function Code 50 104 Figure A24 Function Code 59 105 Figure A25 Function Code 31 106 Figure A26 Function Code 149 107 Figure A27 Function Code 38 109 Figure Dl MCCs with spare breaker cubicles (Photograph 1) 114 Figure D2 MCCs with spare breaker cubicles (Photograph 2) 114 Figure D3 Ducting & trays with extra space (Photograph 3) 114 Figure D4 Ducting & trays with extra space (Photograph 4) 114 Figure D5 Un-shaded Flat roof areas (Photograph 5) 115 Figure D6 Continuous compressed air supplies with easy access (Photograph 6) 115 Figure D7 Un-shaded Flat roof areas (Photograph 7) 115 Figure D8 Ducting & trays with extra space (Photograph 8) 115 Figure D9 Un-shaded Flat roof areas (Photograph 9) 116 Figure D10 Expandable DCS -Marshalling panel (Photograph 10) 116 xi List of Tables Table Page Table 1.1 Tariff rates effective from 1 st January 2011 (Industrial -3) 1 Table 1.2 Plant operational pattern during last 5 years 2 Table 4.1 Efficiency/cost comparison for different cell manufacturing technologies 9 Table 4.2 Important parameters of different materials used to form Thin- film solar cells 12 Table 4.3 Relative Humidity Data for Colombo 16 Table 4.4 Average and Extreme Rainfall Data of Colombo 17 Table 4.5 Wire sizing table 21 Table 4.6 Overview of the possible range of islanding detection techniques 26 Table 5.1 Un-shaded plant roof areas 28 Table 5.2 Final configuration of panels in building roofs 31 Table 5.3 Dimensions and weight of flat iron bars (mild steel) 33 Table 5.4 Dimensions and weight of angle iron bars (mild steel) 33 Table 5.5 Dimensions and weight of cast iron rods 39 Table 5.6 Different conditions effecting solar intensity and panel orientation 47 Table 5.7 Basic Process flow table of tracking system 48 Table 5.8 Two main different conditions which can be used to generate switching signal. 51 Table 5.9 List of function codes used in the project 52 Table 5.10 Panel angle against tracking time 62 Table 6.1 Cost for single frame and shaft unit 65 Table 6.2 Additional expenses for the implementation of a tracking system 66 Table 6.3 Total expenses for the project 67 Table 6.4 Export energy cost 68 Table 6.5 Cost benefit analysis total project 68 Table 6.6 Cost benefit analysis tracking system 69 Table 6.7 Cost benefit analysis without tracking system 69 Table A1 Outputs of Function Code 132 75 Table A2 Specifications of Function Code 132 77 Table A3 Outputs of Function Code 9 77 Table A4 Specifications of Function Code 9 78 Table A5 Outputs of Function Code 2 78 Table A6 Specifications of Function Code 2 78 Table A7 Outputs of Function Code 12 79 Table A8 Specifications of Function Code 12 79 Table A9 Outputs of Function Code 37 80 Table A10 Truth Table of Function Code 37 80 Table Al 1 Specifications of Function Code 37 80 Table A12 Outputs of Function Code 30 81 Table A13 Specifications of Function Code 30 81 xii Table A14 Outputs of Function Code 65 82 Table A15 Specifications of Function Code 65 82 Table Al6 Outputs of Function Code 156 84 Table Al7 Specifications of Function Code 156 85 Table A18 Outputs of Function Code 80 87 Table A19 Specifications of Function Code 80 89 Table A20 Outputs of Function Code 33 90 Table A21 Specifications of Function Code 33 90 Table A22 Outputs of Function Code 8 91 Table A23 Specifications of Function Code 8 91 Table A24 Outputs of Function Code 1 91 Table A25 Specifications of Function Code 1 92 Table A26 Specifications of Function Code 10 92 Table A27 Outputs of Function Code 10 93 Table A28 Specifications of Function Code 11 93 Table A29 Outputs of Function Code 11 93 Table A30 Truth Table of Function Code 35 94 Table A31 Specifications of Function Code 35 94 Table A32 Outputs of Function Code 110 95 Table A33 Specifications of Function Code 110 96 Table A34 Outputs of Function Code 129 97 Table A35 Specifications of Function Code 129 99 Table A36 Outputs of Function Code 69 100 Table A37 Specifications of Function Code 69 100 Table A38 Outputs of Function Code 39 101 Table A39 Truth Table of Function Code 39 101 Table A40 Specifications of Function Code 39 101 Table A41 Outputs of Function Code 115 102 Table A42 Specifications of Function Code 115 102 Table A43 Outputs of Function Code 16 103 Table A44 Specifications of Function Code 16 104 Table A45 Outputs of Function Code 40 104 Table A46 Truth Table of Function Code 40 104 Table A47 Specifications of Function Code 40 104 Table A48 Outputs of Function Code 50 105 Table A49 Specifications of Function Code 50 105 Table A50 Outputs of Function Code 59 105 Table A51 Specifications of Function Code 59 106 Table A52 Outputs of Function Code 31 106 Table A53 Specifications of Function Code 31 107 Table A54 Outputs of Function Code 149 108 Table A55 Specifications of Function Code 149 109 Table A56 Outputs of Function Code 38 110 Table A57 Truth Table of Function Code 38 110 Table A58 Specifications of Function Code 38 110 xiii List of Abbreviations and Units Abbreviation Description AC Alternating current A/D Analog to Digital a-Si (Hydrogenated) amorphous silicon ASTM American Society for Testing and Materials BOS Balance of system CDM Clean Development Mechanism CEB Ceylon Electricity Board CIS Copper indium Di-Selenide CIGS Copper indium Gallium Di-Selenide DC Direct Current DSSC Dye sensitised solar cell EHS Environment, Health and Safety IEC International Electrotechnical Commission IEEE Institute of Electrical and Electronics Engineers (USA) ISO International Standards Organization ITO Indium-tin oxide LV Low voltage MPPT Maximum power point tracker NREL National Renewable Energy Laboratory (USA) O & M Operations and Maintenance PV Photovoltaic, photovoltaics RH Relative Humidity STC Standard Test Conditions UL Underwriters Laboratory (USA) X-Si Crystalline Silicon Unit Abbreviation Description watt(W) W p (peak watt) Wm" 2 G SI unit of power. Symbol is W. power under standard test conditions (STC). peak power at STC (standard test conditions), watts per square meter. Used to measure solar short-wave radiation global short-wave radiation flux, i.e. radiant energy flow per unit time, is known as the irradiance. The integral of irradiance flux over any period is called the irradiation. Typical integration periods are the hour, which yields the hourly global irradiation, Gh.(units MJ m" h"2 or Wh m"2 h"2). the day G d (units MJ m" d* or Wh m" d" )and the month G m (units MJ m per month or Wh m"2 per month). V xiv Term Definition Controller Directs field processes; the Harmony area controller is an example. Control logic document A grouping of sheets containing control logic (usually with a similar purpose). A controller configuration frequently contains multiple control logic documents. Control logic template Preconfigured configuration documents used to simplify the creation of a new control logic document. A control logic template, when dragged into a controller, becomes a control logic document that is identical to the template. Control network Data communication highway. Exchange Project-wide repository of system and user-defined reusable components (symbols, shapes, macros, and documents). These components are organized into folders. Function code An algorithm that manipulates specific functions. These functions are linked together to form the control strategy. Harmony control unit A control network node that contains controllers. Human systems interface Combined hardware and software entity (sometimes just a software application) used by operators to monitor and control the process control system. Project The largest grouping of configuration information (displays, control logic documents, etc.) for a process. Sheet The actual pages of a control logic document on which control logic is inserted. XV List of Appendices Appendix Description Page Appendix -A DCS Function Codes 75 Appendix - B Quotation for Solar PV inverters 111 Appendix - C Quotation for structural materials 113 Appendix-D Photographs for available resources in the plant 114 X V 1