Islanded Operation of a Distribution Feeder with Distributed Generation
Total Page:16
File Type:pdf, Size:1020Kb
UNLV Theses, Dissertations, Professional Papers, and Capstones 2009 Islanded operation of a distribution feeder with distributed generation Chandu Venu University of Nevada Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Power and Energy Commons Repository Citation Venu, Chandu, "Islanded operation of a distribution feeder with distributed generation" (2009). UNLV Theses, Dissertations, Professional Papers, and Capstones. 164. http://dx.doi.org/10.34917/1392891 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. ISLANDED OPERATION OF A DISTRIBUTION FEEDER WITH DISTRIBUTED GENERATION by Chandu Venu Bachelor of Technology in Electronics and Communication Engineering Jawaharlal Nehru Technological University, India May 2007 A thesis submitted in partial fulfillment of the requirements for the Master of Science Degree in Electrical Engineering Department of Electrical and Computer Engineering Howard R. Hughes College of Engineering Graduate College University of Nevada, Las Vegas Decemeber 2009 THE GRADUATE COLLEGE We recommend that the thesis prepared under our supervision by Chandu Venu entitled Islanded Operation of a Distribution Feeder with Distributed Generation be accepted in partial fulfillment of the requirements for the degree of Master of Science Electrical Engineering Yahia Baghzouz, Committee Chair Paolo Ginobbi, Committee Member Yingtao Jiang, Committee Member Laxmi P. Gewali, Graduate Faculty Representative Ronald Smith, Ph. D., Vice President for Research and Graduate Studies and Dean of the Graduate College December 2009 ii ABSTRACT Islanded Operation of a Distribution Feeder with Distributed Generation by Chandu Venu Dr. Yahia Baghzouz, Examination Committee Chair Professor, Electrical and Computer Engineering, University of Nevada, Las Vegas A distribution system that is equipped with distributed generators, such as roof-mounted photovoltaic systems, can operate as a microgrid (i.e., separated from the grid) under some specific conditions. A key feature of a microgrid is its ability to separate and isolate itself from the utility seamlessly with little or no disruption to the loads within the microgrid. Then, when the utility grid returns to normal, the microgrid automatically resynchronizes and reconnects itself to the grid, in an equally seamless manner. This thesis addresses the conditions necessary for proper microgrid operation: these include local generation-load mismatch, local energy storage, load switching, and voltage and frequency control. Computer simulations using Matlab/Simulink will be conducted under various scenarios to validate such necessary conditions. iii ACKNOWLEDGMENTS I am extremely happy to take this opportunity to acknowledge my debts and gratitude to those who were associated with the preparation of this thesis. Words fail to express my profound regards from the inmost recess of my heart to my advisor Dr. Yahia Baghzouz for the invaluable help, constant guidance and wide counseling extended to me right from the selection of the research topic to the successful completion of this thesis. Academic assistance apart, I would like to thank him sincerely for his infinite patience which was one of the driving forces for me to successfully complete this thesis. I am extending my sincere thanks to Dr. Yingtao Jiang , Dr. Paolo Ginobbi, Dr. Laxmi Gewali for their direct and indirect contribution throughout this investigation. I owe deepest gratitude to my friend Reshma Koganti without whom, this thesis would not have been possible. I would like to give special thanks to my parents and brother for their continuing love and affection throughout my life and career. Finally, I am indebted to my colleagues, Rakesh Choudary Malepati, Rohit Reddy Saddi, Anup Kumar Miryala and Aditya Chainulu karamcheti, Varun Reddy Seva for their help, support, interest and allowing me to concentrate major part of my time on thesis. iv LIST OF FIGURES Figure 1.1 Block Diagram of a Grid connected PV System. ........................................... 6 Figure 2.1 Influence of ambient irradiation on cell’s temperature ................................ 13 Figure 2.2 Basic Buck converter which is used as DC-DC boost ................................. 16 Figure 2.3 IV curve of MPPT ........................................................................................ 19 Figure 2.4 75W PV module power/voltage/current at standard test conditions ............ 19 Figure 2.5 Full Bridge IGBT inverter ............................................................................ 20 Figure 2.6 Waveform of a single phase full bridge Inverter .......................................... 22 Figure 3.1 One diode equivalent model of photo-voltaic panel ..................................... 32 Figure 3.2 Current-Power of PV as a factor of Vpu voltage ........................................... 33 Figure 3.3 The photo voltaic module ............................................................................. 35 Figure 3.4 IGBT diode inverter (DC-AC) ..................................................................... 38 Figure 3.5 A PWM IGBT inverter ................................................................................. 39 Figure 3.6 Schematic diagram of a grid tied inverter with load .................................... 41 Figure 3.7 Parallel Resistive (R) and Inductive (L) load ............................................... 42 Figure 3.8 Alternating Current Utility ........................................................................... 42 Figure 3.9 AC voltage connected to a thevenin inductance L1 ..................................... 43 Figure 4.1 Electrical model of DC voltage source connected to an Inverter ................. 45 Figure 4.2 Square wave from the inverter before the filter LC circuit .......................... 46 Figure 4.3 Sinusoidal waveform obtained from the Low pass LC filter. ...................... 47 Figure 4.4 Parallel RL load connected to a stand-alone inverter ................................... 48 Figure 4.5 PQ waveform from the photo voltaic module/DC source ............................ 49 Figure 4.6 AC voltage source with Thevenin inductance connected to a RL load ........ 50 v Figure 4.7 Voltage waveform from the Utility grid ....................................................... 51 Figure 4.8 PQ waveform from the utility grid ............................................................... 52 Figure 4.9 RL load connected to both DC source and AC utility grid .......................... 53 Figure 4.10 PQ graph from Utility when load is connected to two sources .................... 54 Figure 4.11 PQ graph from DC source when load is connected to two sources.............. 55 Figure 4.12 Grid-connected PV system with local load .................................................. 60 Figure 4.13 Inverter Voltages, Frequency & Output Real and Reactive Power .............. 67 Figure 4.14 Inverter Voltage, Frequency & Output Real and Reactive Power (fn) ........ 67 Figure 4.15 Case B Inverter Voltage, Frequency & Output Real and Reactive Power ... 67 Figure 4.16 Case C Inverter Voltage, Frequency & Output Real and Reactive Power ... 67 Figure 4.17 Case D Inverter Voltage, Frequency & Output Real and Reactive Power ... 67 Figure 4.18 Case E Inverter Voltage, Frequency & Output Real and Reactive Power ... 68 vi TABLE OF CONTENTS ABSTRACT ....................................................................................................................... iii ACKNOWLEDGEMENTS ............................................................................................... iv LIST OF FIGURES ............................................................................................................ v CHAPTER 1 INTRODUCTION ........................................................................................ 1 1.1 Introduction ............................................................................................................ 1 1.1.1 Microgrids ..................................................................................................... 2 1.1.2 Islanding ........................................................................................................ 2 1.1.3 Reasons for Microgrid .................................................................................. 6 1.2 Stimulus for Microgrid .......................................................................................... 7 1.3 Management of Microgrid ..................................................................................... 8 1.4 Objective and contribution of thesis ...................................................................... 8 1.5 Modeling of Microgrids ......................................................................................... 9 1.6 Outline of thesis ....................................................................................................