MODELING OF HYBRID RENEWABLE ENERGY GENERATION CONSISTING OF WIND, FUEL CELL AND ULTRA CAPACITOR MOHAMMAD FATHI A project report submitted in partial fulfilment of the requirements for the award of the degree of Master of Engineering (Electrical - Power) Faculty of Electrical Engineering Universiti Teknologi Malaysia MAY 2011
iii To God the Almighty, without whom knowledge without faith is fruitless and to my lovely parents and my sisters and brother, who do not let me sense me alone.
iv ACKNOWLEDGEMENT First of all, I am greatly indebted to ALLAH SWT to make this project successful. I would like to acknowledge my supervisor Professor Ir. Dr. Abdullah Asuhaimi bin Mohd Zin who has given me support and guidance throughout the period of this research. His patience and perseverance towards the outcome of this study is of the highest standard. Without him this project could not become a reality. Last but not least, I would like to thank other Faculty of Electrical Engineering (FKE) staffs and my family for their motivation and moral supports.
v ABSTRACT Consider to the finish of fossil fuel and the growth of population, the need of creating and utilizing new sources of energy is increased. During the past few decades, scientists have discovered new resources to generate electricity. These kinds of energy are called renewable energies. Alongside all the benefits of new resources they have some disadvantages that cannot use them widely. For example, one of the issues in generating electricity from wind is the variation of wind speed. In the case of having an ideal generation of electricity, the use of stable and power quality curve is necessary. But this variation of wind speed sometimes makes a problem in drawing this curve. In order to solve this problem, this study offered the utilizing of the wind and fuel cells as renewable energy in a hybrid configuration. This configuration can solve problems of renewable energy. In this project, the generating of electricity is hydride from wind turbines and fuel cell. If the speed of wind is not enough to generate the electricity, the fuel cell would start to generate it. However, the fuel cell needs the time to arrive nominal value which ultra capacitor start to generate the electricity in this gap. All the system consists of grid, wind turbine, fuel cell and ultra capacitor was simulated in MATLAB software. The output of system should be a stable carve. It means this hybrid system s generation as a reliable production is used in all wind speed condition. By using this, the disadvantage of using wind is reduced and also the power quality of distribution s grid and electricity production be improved.
vi ABSTRAK Kekurangan bahan api sejak kebelakangan ini memberi motivasi untuk mencari sumber tenaga yang baru. Beberapa dekad yang lalu, para ahli saintis telah mempelajari bagaimana penggunaan sumber tenaga dalam penghasilan elektrik. Tenaga yang dimaksudkan ialah tenaga yang boleh di perbaharui. Walaupun tenaga yang boleh diperbaharui mempunyai banyak kebaikan tetapi keburukan yang ada padanya telah menghalang penggunaan sumber tersebut secara berleluasa. Contohnya, kepelbagaian kelajuan angin merupakan isu yang besar dalam tenaga angin. Bagi menghasilkan penjanaan yang sempurna, penghasilan elektrik perlu dilakukan dalam lengkungan yang tepat. Bagi menyelesaikan masalah tersebut, penggunaan sumber tenaga secara hibrid telah diperkenalkan dalam projek ini. Dua sumber tenaga boleh diperbaharui telah digunakan iaitu fuel cell and tenaga angin. Dalam keadaan tenaga angin tidak mencukupi, tenaga akan dihasilkan daripada fuel cell. Dengan kata lain, apabila pengeluaran angin berkurangan, tenaga akan mula dihasilkan daripada fuel cell. Walaubagaimanapun, fuel cell memerlukan masa untuk mencapai nilai yang nominal yang mana masalah ini dapat diatasi dengan menggunakan kapasitor sebagai penyimpan tenaga. Sistem yang terdiri daripada penjana angin, fuel cell dan kapasitor telah di analisis dalam perisian MATLAB. Keluaran sistem tersebut perlu dalam lengkungan yang tepat. Ini bermakna, dalam sistem hibrid ini, penjanaan tenaga boleh dalam semua keadaan angin. Oleh yang demikian, sumber tenaga boleh diperbaharui dapat digunakan secara meluas. Akhir sekali, jumlah kos penghasilan tenaga elektrik akan semakin berkurangan.
vii TABLE OF CONTENTS CHAPTER TITLE PAGE DECLARATION DEDICATION ACKNOWLEDGMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF SYMBOLS LIST OF APPENDICES ii iii iv v vi vii x xii xiii xv 1 INTRODUCTION 1 1.1 Background of the Study 1 1.2 Significance of Study 3 1.3 Problem statements 4
viii 1.4 Objective of Study 5 1.5 Scope of Study 5 1.6 Organization of the Report 5 2 LITERATURE REVIEW 7 2.1 Introduction 7 2.2 System description 10 2.2.1 Wind Energy Conversion System 11 2.2.1.1 Advantages 12 2.2.1.2 Disadvantages 13 2.2.1.3 Description of wind turbine characteristics 2.2.2 Fuel Cell (FC) 2.2.2.1 Technology Basics 2.2.2.2 Types of fuel cells 2.2.2.3 Advantages 2.2.2.4 Disadvantages 2.2.2.5 Model Assumptions 2.2.2.6 Model Limitations 2.2.2.7 Applications 2.2.2.8 Stationary power 2.2.2.9 Hydrogen Generation 2.2.3 Storage and Ultra Capacitor 14 16 18 18 19 21 21 22 22 23 23 25
ix 2.2.3.1 Ultra Capacitor 2.3 Design of the Hybrid System 2.4 Summary 27 30 31 3 METHODOLOGY 32 3.1 Introduction 32 3.2 Data Collection 3.2.1 Load demand, PD 3.2.2 Generation limit, P max and P min 3.2.3 Wind speed 3.2.4 Wind generator capacity 3.2.5 Maximum allowed delay for generation 3.2.6 FC capacity of generation and H2 storage tank 3.3 System Elements 3.3.1 Wind turbine compound with generator (doubly-fed induction generation or DFIG) 3.3.2 Fuel Cell (FC) 3.3.3 Ultra Capacitor (UC) 3.4 Assumptions 3.5 Limitations 3.6 Design hybrid system 3.7 The economical assessment of hybrid system by HOMER 34 34 34 35 35 35 36 36 36 41 44 46 46 46 48
x 3.8 Summary 49 4 RESULTS 50 4.1 Introduction 50 4.2 Wind Energy Conversion System 51 4.3 Fuel Cell 53 4.4 Ultra capacitor 4.5 Design of the Hybrid System 54 56 4.5.1 FC and wind generate (both start t=0s) 57 4.5.2 FC and wind generate with UC (all start t=0s) 58 4.5.3 FC (start t=0s) and wind generate with delay 4.5.4 FC and UC (start t=0) and wind generate with delay 4.6 Summary 58 59 60 5 CONCLUSIONS 61 5.1 Introduction 61 5.2 Conclusions 61 5.3 Suggestions for Future Works 62 REFERENCES 64 APPENDX A 66
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xii LIST OF FIGURES FIGURE NO. TITLE PAGE 2.1 Wind-Fuel Cell hybrid energy system 9 2.2 Two different of wind turbine model 12 2.3 Wind speed, scaled data daily profile 14 2.4 The Wind Turbine and the Doubly-Fed Induction Generator System15 2.5 Fuel Cell 17 2.6 Basic fuel cell components 17 2.7 The exhaust of fuel cell after generating electricity is water 20 2.8 PEM fuel cell system block diagram 22 2.9 Classical equivalent model for the UC unit 29 3.1 Flow Chart for Project s Methodology 33 3.2 The Block diagrams of wind turbine and drive train 37 3.3 The Simulink model of the wind turbine 38 3.4 The Simulink model of the drive train connect to wind turbine 38 3.5 Block diagram of doubly fed induction generator 39 3.6 Block diagram of Fuel Cell 42 3.7 Dynamic model of solid oxide Fuel cell (SOFC) 43 3.8 Block diagram of FC and its inverter before connect to grid 44 3.9 Simulink equivalent model for the UC unit 45 3.10 Block diagram of UC and its inverter before connect to grid 45 3.11 Schematic picture of Hybrid generation consist of wind turbine, FC and UC 47 3.12 Connections of three elements of system 48 4.1 The result of wind turbine and generator if the wind
xiii at the time t=0 be 1pu 51 4.2 The voltage and current output of wind turbine in volt and ampere unit 52 4.3 The RMS value of voltage and current output of wind turbine in volt and ampere unit 52 4.4 The value of generation from FC 53 4.5 The voltage and current of FC in volt and ampere unit 54 4.6 Power generated by UC in t=0s 55 4.7 The voltage and current of FC in volt and ampere unit 55 4.8 The RMS value of voltage and current of UC in volt and ampere unit 56 4.9 Generating result of wind and FC when all start from t=0s 57 4.10 Generating result of wind, FC and UC when all start from t=0s 58 4.11 Generating result of wind and FC when FC start at t=0s and wind start at t=0.4s 59 4.12 Generating result of wind, FC and UC when FC and UC start at t=0s and wind start at t=0.4s 59
xiv LIST OF ABBREVIATIONS FC - Fuel Cell UC - Ultra Capacitor NREL - National Renewable Energy Laboratory s WT - Wind Turbine PEM - Proton exchange membrane or Polymer Exchange Membrane DFIG - Doubly fed induction generation IG - Induction Generator MCFC - Molten Carbonate SOFC - Solid Oxide Fuel Cell AFC - Alkaline Fuel Cell PAFC - Phosphoric acid Fuel Cell DMFC - Direct Methanol Fuel Cell ESR - Equivalent series resistance EPR - Equivalent parallel resistance PF - Power Factor VSC - Voltage-sourced converters IEEE - The Institute of Electrical and Electronics Engineers
xv LIST OF SYMBOLS P - Mechanical output power of turbine C - Performance coefficient of the wind turbine λ - Tip speed ratio of the rotor blade tip speed to wind β - Blade pitch angle ( ) ρ - Air density (kg/m ) A - Turbine swept area (m ) v - Wind speed ( ) n - Hydrogen produced (moles/sec) ηf - Faraday efficiency=96.5e (.. ) ηc - Number of electrolyzer cells in series i - Electrolyzer current F - Faraday constant (CK/mol) T - Temperature of operation z - Number of moving electrons i 0 - Exchange current E n - Nernst voltage
xvi α - Charge transfer coefficient C - Capacitance [F] CUC-total - The total UC system capacitance [F] EPR - Equivalent parallel resistance [Ω] ESR, R - Equivalent series internal resistance [Ω] EUC - The amount of energy released or captured by the UC bank [Ws] ns - The number of capacitors connected in series np - The number of series strings in parallel R UC-total - The total UC system resistance [Ω] V - The initial voltage before discharging starts [V] V - The final voltage after discharging ends [V] T m - Shaft mechanical torque
xvii LIST OF APPENDICES APPENDIX TITLE PAGE A Feasibility of hybrid renewable energy types consist of Wind, Fuel Cell with CHP, Diesel Generator and Battery under Alaska condition 67
CHAPTER 1 INTRODUCTION 1.1 Background of Study With the developed of world, it seemed the energy was the main part for improving economic and social development and also it drives a good living standard. Due to increased access to electricity, it will improve opportunities for industrial development and enhances health and education. Renewable Energy (RE) has a great potential to contribute to development of national sustainable energy infrastructures in many countries in the world. Hybrid Renewable Energy is a combination of more than one type of energy in one system. For instance, Fuel cell and wind can become one hybrid type of Renewable energy generation. A hybrid energy system based on such alternative technologies has been proven to be a feasible solution for stand-alone power generation at remote locations, where the cost of grid extension is prohibitive and the price of fossil fuels increase drastically. Moreover, the hybrid systems such as wind/diesel are now proven technologies and are an option to supply small electrical loads at remote locations as reported by Zhang Hongyi et al., Lundsager and Bindner [1].
2 A wind system alone cannot satisfy the load requirement for 24 hours. Stand-alone diesel generator sets are generally expensive to operate and maintain especially at low load levels. In simple system, the diesel runs continuously to cover the difference between the load demand and the wind energy, as a result the diesel generator runs sometimes under light-load conditions. Due to low efficiency of the generator at light load, the fuel saving potential is limited. Wind and diesel have complementary characteristics namely, capital cost of diesel is lower compared with wind turbine system, maintenance requirements of wind are less compared to diesel, and diesel energy is available all the time where as the availability of wind energy is dependent on the wind. Battery technology has reached a very suppurate stage; size, cost and disposal are the constraining factors for its use in remote stand-alone applications. Recent advancements in Fuel Cell (FC) and electrolyzer technology have opened up the option for using hydrogen as an energy storage medium [2]. Some studies are reported about design, optimum combination and analysis of hybrid renewable energy power generations with energy storage. The overall goal is to identify the current availability of commercial hybrid renewable energy systems and its components by using Homer software. Inputs to HOMER will perform an hourly simulation of every possible combination of components entered and rank the systems according to user-specified criteria, such as cost of energy (COE, US$/kWh) or capital costs. Furthermore, HOMER can perform sensitivity analyses in which the values of certain parameters (e.g., solar radiation or wind speed) are varied to determine their impact on the system configuration [3] Standalone diesel generating system utilized in remote islands has long been practiced in Alaska. Because of high fluctuation diesel price, such a system is seemed to be uneconomical, particularly in the long run if the supply of electricity for rural areas only depends on such diesel generating system. Here the potential use of hybrid
3 Wind/Fuel cell (FC)/Battery /diesel energy system was analyzed in remote areas. National Renewable Energy Laboratory s (NREL) HOMER software was used to present the techno economic feasibility of hybrid Wind/Fuel cell (FC) /Battery/diesel energy system. The investigation verified the impact of wind/ FC penetration and battery storage on energy production, cost of energy and number of operational hours of diesel generators for the given hybrid configuration. Emphasis has also been placed on percentage fuel savings and reduction in carbon emissions of different hybrid systems. At the end, suitability of utilizing hybrid Wind/Fuel cell (FC)/Battery /diesel energy system over standalone diesel system would be discussed mainly based on different load demand, wind speed, FC and diesel prices. In order to determine the economic and technical feasibility of a wind/fuel cell/diesel system, computer modeling of the different power system options have to be done [4]. 1.2 Significance of Study This project needs to be solved. Notice to this case that it should feed all demand loads with different types of generation with enough power, reliable voltage and frequency in our grid. Thus for having a reliable power system, it needs to assess our system in two status. First of all before start to design each system it is necessary to have an economical assessment. It is mean that, if it was assumed to make a power plant for generating electricity. In this case it s so important the low cost of production. In the other word, the electricity generation in new power plant should not be more expensive in compare to normal generation on that place. Second of all, the new planned system should be able to work in normal and abnormal condition. It means this new system capable to work in practical state. Thus this system has to assess from technical viewpoints. Each parts has own characteristics for having a best work points.
4 The disadvantages of these renewable types are: In wind turbine: the wind speed is variable and sometimes it stops to blow. Fuel cell: cannot supply load in long duration and takes time to start to generate power. For having a good quality of electricity, should not have any interruption or blackout for delivering electricity to consumers. 1.3 Problem statements The problem statements of this project are: a) The disadvantages of these renewable types. In wind turbine: the wind speed is variable and sometimes it stops to blow Fuel cell: cannot supply load in long duration and takes time to start to generate power b) For having a good quality of electricity, should not have any interruption or blackout for delivering electricity to consumers
5 1.4 Objective of Study The objectives of this study are: 1) To generate a system consisting of wind, FC and UC. 2) This system should generate power demand (active power) by the best output (sustain generation and fast starting) and deliver this power to grid. 1.5 Scope of Study The scope and limitation of the study are as follow: 1) Handling of the modeling of wind turbine (WT), Fuel Cell (FC) and Ultra Capacitor (UC) to generate a good quality and quantity of power for deliver to grid. 2) Integrated these three different types to get better results. 3) The simulation by using MATLAB 7.0 Simulink for technical part and using HOMER software to do economical assessment. 1.6 Organization of the Report This thesis is divided into five chapters. The first chapter is the significance of the study, followed by chapter 2, which discuss about the literature review and previous study. Chapter 3 describes about the methodology of the system. The results and
6 discussions will be discussed in Chapter 4. The last chapter provides the conclusion of the study.
64 REFERENCES [1]. Himri, Y.. "Techno-economical study of hybrid power system for a remote village in Algeria", Energy, 2008 [2] Shaahid, S.M.. "Prospects of autonomous/stand-alone hybrid (photo-voltaic + diesel + battery) power systems in commercial applications in hot regions", Renewable Energy, 2004 [3] P. Vacent. "Balancing Cost, Operation and Performance in Integrated Hydrogen Hybrid Energy System", First Asia International Conference on Modelling & Simulation (AMS 07), 03/2007 [4] Lau, K.Y.. "Performance analysis of hybrid photovoltaic/diesel energy system under Malaysian conditions", Energy, 2010 [5] http://web.mit.edu/smaurer/oldfiles/public/joeenergy/2onar.pdf [6] Onar, O.C.. "Dynamic modeling, design and simulation of a wind/fuel cell/ultracapacitor- based hybrid power generation system", Journal of Power Sources, 2006 page 1020 [7] Khan, M.J.. "Dynamic modeling and simulation of a small wind-fuel cell hybrid energy system", Renewable Energy, 2005 [8]Powered by vbulletin Version 3.8.1 Copyright 2000-2011, Jelsoft Enterprises Ltd. http://www.greensmartforum.com/showthread.php?p=1159 [9] http://answers.yahoo.com/question/index?qid=20091210091238aabp7lr [10] http://home.zcu.cz/~tesarova/ip/proceedings/proc_2008/files/030-034%20kanalik_lizak.pdf [11] Except where otherwise noted, text content on Climate Lab is licensed under a Creative Commons Attribution Share Alike license. Powered by MindTouch Enterprise 2009. http://climatelab.org/fuel_cells
65 [12] Matlab Software Help manual in Fuel Cell. (2009). Publisher: The Math Works Inc.,http://www.mathworks.ch/access/helpdesk/help/toolbox/physmod/powersys/ref/fuel cellstack.html [13] Ghosh, P.C.. "Comparison of hydrogen storage with diesel-generator system in a PV-WEC hybrid system", Solar Energy, 2003 [14] http://energy.nuvention.org/docs/energy%20storage%20review.pdf [15]Dr.Christine Ortiz Department of Materials Science and Engineering MIT, http://in.materials.drexel.edu/blogs/580_high_temp_energy/attachment/3143.ashx [16] Matlab Software Help manual in Wind-Farm-DFIG-Model. (2009). Publisher: The Math Works Inc http://www.scribd.com/doc/16307205/wind-farm-dfig-average- Model