the design and testing of a wind...
TRANSCRIPT
THE DESIGN AND TESTING OF A WIND TURBINE FOR
ELECTRICAL POWER GENERATION IN MALAYSIAN WIND CONDITIONS
CHONG WEN TONG
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Doctor of Philosophy
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
AUGUST 2006
iii
This fruit of my efforts,
I humbly dedicate to ……
my beloved family members (especially my grandmother);
who have truly shaped my life
and my wife;
who has influenced my life in a wonderful way.
God bless all of you
iv
ACKNOWLEDGEMENT
First, the author would like to thank God, for giving him His infinite grace,
love and blessings, to enable him to pursue his ambition up to this point of his life.
The author would also like to take this opportunity to express his heartfelt
appreciation and thanks to his respectful supervisor, Prof. Ir. Dr. Hj. Abas Ab.
Wahab, for his supervision, encouragement, constructive ideas, guidance and
invaluable advice, enabling the author to achieve the objective of this project.
The author is very grateful to the Malaysian Meteorological Department for
providing the regional wind speed data. The financial support provided to this
research by Ministry of Science, Technology and the Environment through IRPA
project is also gratefully acknowledged. Thanks and appreciation are also extended
to all the lecturers and technicians in UTM, and numerous other individuals (Mr.
Lim Choun Sian, Mr. Ling Kong Siong, Mr. Tan C. M., Mr. Mohamad Said and Mr.
Ling C. T.) who have contributed their efforts, information, material and equipment
for the completion of this project.
As for the author’s family members and wife, no amount of gratitude could
replay your kindness of being there as well as the patience to put up with the author’s
whim. His deepest gratitude is meant for all of you.
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ABSTRACT
Malaysia is situated in the equatorial zone and experiences low and unsteady
wind speed. As a result, most of the existing wind turbines are not suitable for
Malaysian application. High capital cost, low regional wind speed, incorrect
matching between existing wind turbines and available wind speed as well as the
level of technology are barriers to the use of wind energy conversion system. This
project is a study on low cost, medium rotational speed, small scale stand-alone wind
turbine for electrical power generation in low wind speed region. It involves
designing, fabricating, testing and determining (blade and rotor configuration) a
suitable wind turbine. A study on wind resources in Malaysia and the feasibility of
its application showed that there is a possibility to utilise wind energy especially in
the coastal areas and islands. The conceptual design of the wind turbine prototype
was developed by considering the aspects of application requirements, configuration,
functions and performance. The rotor blades were the most critical parts and they
were analysed using aerodynamic theory. Wind turbine rotor models were fabricated
and tested in a wind tunnel. The components and mechanisms were designed, built
and analysed through computer-aided-design (CAD) modeling, theoretical
calculation and computer software simulation. Various loads on the wind turbine
structures were also examined. An indoor test rig was built for the testing of the
wind turbine prototype, in order to obtain the power and torque coefficient at various
tip speed ratio (CPmax = 36.8%). The prototype was also field tested to verify its
start-up speed and feasibility of power generation. It has demonstrated good strength,
component integrity and yaw response in the field test. The findings suggested that
the optimum performance of this innovative wind turbine (TSR = 2.7 - 4.0) falls in
the operating range that matched with the available wind speed (V∞ = 2.2 - 7.0 m/s) if
the load matching is properly done. The work developed is sufficient for further
investigation into the refinement of every sub-assembly of the system.
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ABSTRAK
Malaysia terletak di zon khatulistiwa, dan mengalami kelajuan angin yang
rendah dan tidak stabil. Oleh itu, kebanyakan kincir angin sedia adalah tidak sesuai
untuk kegunaan di Malaysia. Kos kapital yang tinggi, halaju angin tempatan yang
rendah, ketidak-sesuaian kincir angin sedia ada dan tahap teknologi merupakan
halangan kepada penggunaan sistem penukaran tenaga angin. Kajian ke atas kincir
angin kos rendah, berkelajuan putaran sederhana, berskala kecil dan beroperasi
secara bersendirian telah dilaksanakan di dalam projek ini. Ia melibatkan rekabentuk,
fabrikasi, pengujian dan penentuan (bilah dan konfigurasi rotor) kincir angin yang
sesuai. Hasil kajian ke atas sumber angin di Malaysia dan kebolehlaksanaannya,
tenaga angin didapati berpotensi untuk digunakan terutamanya di kawasan tepi pantai
dan pulau. Rekabentuk konsep untuk prototaip kincir angin telah dibangunkan
dengan mengambilkira aspek keperluan kegunaan, konfigurasi, cara berfungsi dan
perilaku. Bilah rotor merupakan bahagian yang paling kritikal, dan telah dianalisa
menggunakan teori aerodinamik. Model rotor kincir angin telah difabrikasi dan diuji
dalam terowong angin. Komponen dan mekanisma telah direkabentuk, dibina dan
dianalisa melalui permodelan CAD, pengiraan secara teori dan simulasi perisian
komputer. Pelbagai beban ke atas struktur kincir telah dinilai. Sebuah kelengkapan
pengujian dalam makmal telah dibina untuk menguji prototaip kincir angin bagi
memperolehi pekali kuasa dan daya kilas pada pelbagai nisbah kelajuan hujung
(CPmax = 36.8%). Prototaip ini juga diuji di lapangan bagi mengesahkan kelajuan
permulaan dan kebolehlaksanaannya untuk penjanaan kuasa. Ia telah menunjukkan
keupayaan yang baik, integriti komponen dan keupayaan untuk menukar arah
rewangan dalam ujian lapangan. Hasil perolehan menunjukkan bahawa perilaku
optimum kincir angin yang inovasi ini (TSR = 2.7 – 4.0) berada dalam lingkungan
operasi yang berpadanan dengan kelajuan sumber angin yang ada (V∞ = 2.2 – 7.0 m/s)
jika imbangan beban dilakukan dengan betul. Hasil kerja ini juga memadai untuk
penyelidikan lanjutan ke atas setiap bahagian sistem secara terperinci.
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TABLE OF CONTENTS
CHAPTER TITLE PAGE
TITLE PAGE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xvi
LIST OF FIGURES xvii
LIST OF SYMBOLS xxviii
LIST OF APPENDICES xxx
1 THESIS INTRODUCTION 1
1.1 Introduction 1
1.2 Problem Statement 4
1.3 Objective, Aim and Importance of Research 6
1.4 Research Scope and Methodology 8
2 GENERAL REVIEW OF WIND TURBINE SYSTEM 13
DESIGN PROCESS
2.1 Works Done on Wind Energy Locally / 13
Regionally
2.2 Wind Turbine Design Procedure / Approach 16
2.3 End Use of WECS and Energy-demand Assessment 20
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2.4 Wind Energy Supply and Wind Data Analysis 22
2.4.1 Power from the Wind 23
2.4.2 Wind Distribution Curves 25
2.4.2.1 Time Distribution Curves 26
2.4.2.2 Frequency Distribution Curves 27
2.4.2.3 Duration Curves 28
2.4.2.4 The Frequency of Intervals with 29
Low Wind Speeds
2.4.2.5 Maximum Wind Speed 29
2.4.3 Wind Distribution Data Analysis and 30
Wind Power Calculation
2.5 Wind Site Assessment and Selection for Prototype 37
Testing
2.5.1 Wind Site Assessment 37
2.5.2 Test Site and Tower Height Selection 43
2.6 Key Features and Selection of Wind Electric System 47
(WES) for Remote Power Requirements
2.6.1 Principal Classes of Wind Turbine 47
2.6.2 Previous Wind Electric Systems Design and 49
Experience
2.6.2.1 Wind Electric System (WES) 51
- Project Brief
2.6.2.2 Application and Cost Effectiveness 52
2.7 Stand-alone Wind Turbine Configuration and 53
Component Design
2.7.1 Tower 54
2.7.2 Wind Turbine Rotor 54
2.7.3 Rotor Hub Design 57
2.7.4 Rotor Blade Design 58
2.7.5 Yaw Control / Orientation Systems 61
2.8 Estimation of Components and System Efficiencies 62
2.9 Wind Turbine Performance and Load Matching 64
2.9.1 Matching of Wind Turbine and Load 64
2.9.2 The Required Data 67
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2.9.3 The Matching Procedure 69
2.9.4 Practical Hints to Obtain the Generator 70
Parameters
2.10 Wind Turbine Aerodynamic Design 72
2.10.1 Aerodynamic Models 72
2.10.2 Airfoil Aerodynamics Requirements 74
2.11 Wind Turbine Structural Design 75
2.11.1 Wind Turbine Blade Loads 76
2.11.2 Structural Analysis 79
2.11.3 Placement of Rotor Blade Supporting Arm 79
2.12 Generator Characteristics 80
2.12.1 Synchronous Machine (SM) 80
2.12.2 Asynchronous (induction) Machine (AM) 81
2.12.3 Low RPM Permanent Magnet DC Generator 82
2.12.4 The Automobile Generator 82
2.13 Instrumentation and Data Acquisition 87
for Wind Turbine System Testing
2.14 The Testing of Wind Electric System 90
2.14.1 Test of Energy Output 91
2.14.2 Testing of the Generated Power 91
2.14.3 Test for Research and Development Purposes 92
3 AERODYNAMIC ASPECT OF SMALL WIND TURBINE 94
3.1 Introduction 94
3.2 Small Wind Turbine Technology and Design Criteria 95
3.2.1 Electrical and Mechanical Layout of Wind 97
Turbines
3.2.2 Small Turbine Sizes for Low-wind Speeds 98
3.2.3 Application and Requirements / Design Criteria 99
of the Stand-alone Wind Electric System
3.3 Basic Axial Momentum Theory 100
3.4 Blade Element Theory 102
3.5 Momentum Theory for a Turbine with a Rotating Wake 105
x
3.6 Annulus Flow Equation and Strip Theory 107
(Wind-axis Rotor)
3.7 Lift, Drag and Airfoil 111
3.7.1 Lift and Drag 111
3.7.2 Airfoil 114
3.8 Some Aerodynamic Aspects of Wind Turbine 116
Rotor Design
3.8.1 Local Optimisation 117
3.8.2 Design Parameters 118
3.9 Starting Performance of Small Wind Turbine 122
4 INNOVATIVE ROTOR BLADE AND COMPONENTS 126
DESIGN OF MEDIUM ROTATIONAL SPEED WIND
TURBINE PROTOTYPE
4.1 Wind Turbine Prototype Design for Rural or 126
Isolated Areas with Low Wind Speeds
4.2 Load Determination and Power Requirement 130
Matching
4.3 Medium Speed Horizontal Axis Wind Turbine 135
Prototype - Rotor Configuration and Components
Arrangement
4.4 Components and Systems Efficiency 137
4.5 Selection and Analysis of Airfoil for Rotor Blade 138
4.5.1 Design Concept 139
4.5.2 Main Rotor Blade (AE Blade) 139
4.5.3 Starter Rotor Blades 144
4.5.4 Tip Vane Attached to AE Blade for Indoor 147
Testing
4.6 Aerodynamic Design and Performance Analysis 148
of Innovative Rotor Blade (AE Main Blade & Delta
Starter Blade)
4.6.1 Rotor Blade Geometry and Factors Considered 148
4.6.1.1 Critical Design Wind Speed in Wind 149
Turbine Design
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4.6.1.2 Rotor Weight and TSR Range 150
4.6.1.3 Wind Speed-Wind Turbine-Generator 150
Load Matching
4.6.2 Main Rotor Blade (AE Blade)-Innovative and 151
Low Cost Rotor Design
4.6.2.1 Rotor Diameter 151
4.6.2.2 Airfoil and Rotor Design 151
4.6.2.3 Strip Theory-Theoretical Rotor 152
Performance Analysis
4.7 Structural Design and Analysis of Wind Turbine System 156
4.7.1 Weight and Balance 156
4.7.2 Safety Factor for Wind Turbine Structures 157
4.7.3 Placement of Main Rotor Arm 157
(Blade Holding and Supporting)
4.7.4 Wind Turbine Component Analysis 158
4.8 Over-speed Control Device Design of Wind Turbine 162
Prototype
4.9 Automobile Alternator for Prototype Testing 166
4.10 Wind Speed-Wind Turbine Prototype- Alternator 168
Load Matching
5 WIND TURBINE PROTOTYPE CONSTRUCTION AND 171
INSTALLATION
5.1 Wind Turbine System Description and 171
Components Arrangement
5.2 Wind Turbine Component Design and Construction 177
5.2.1 Turntable Assembly 177
5.2.2 Slip-ring Assembly 182
5.2.3 Rotor Assembly 184
5.2.3.1 Main Blades and Starter Blades with 184
Rotor Arms
5.2.3.2 Rotor Hub Assembly 187
5.2.3.3 Rotor Center Shaft with Strut Wire 188
Holder
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5.2.3.4 Rotor Supporting Struts 189
5.2.4 Tail Assembly 189
5.2.5 Drive Assembly and Alternator Mounting 191
5.3 Tower Foundation, Fabrication and Erection 193
5.3.1 Tower Foundation 193
5.3.2 Tower Fabrication 193
5.3.3 Tower Erection 196
5.4 Wind Turbine System Installation at Test Site 197
5.4.1 Installation of Wind Turbine on Temporary 197
Stand
5.4.2 Lifting and Installation of Wind Turbine 199
System Tower
5.5 Problem Faced in Designing, Fabrication and 200
Installation of Wind Turbine System
5.6 Cost of WECS Prototype 201
6 INDOOR TESTING FACILITY CONSTRUCTION 203
AND WIND TURBINE SYSTEM INDOOR TESTS
6.1 Introduction - Indoor Testing 203
6.2 Purpose of the Set-up of Indoor Testing Facility 205
(Fans Rig)
6.3 Indoor Testing Facility Design and Construction 207
6.3.1 Introduction 207
6.3.2 Fan Mounting Rig Design and Fabrication 208
6.4 Set-up of Instrumentation and Data Acquisition 211
for Indoor Testing of Wind Turbine Rotor
6.4.1 Determining Fans Configuration 211
6.4.2 Measurement Devices Needed 212
6.4.3 Preliminary Measurements 215
(Wind Speed Profile - Type A and Type B)
6.4.4 Summary and Recommendation for 216
Future Upgrading
6.5 Indoor Alternator-Battery Testing 217
- Torque vs. RPM
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7 WIND TURBINE SYSTEM FIELD TESTS 222
7.1 Field Test Preparation Works 222
7.1.1 Wind Turbine Prototype 222
7.1.2 Installation and Maintenance Rig 224
7.2 Field Test Measuring Devices and Equipment 224
Preparation
7.2.1 Wind Speed Measurement 224
7.2.2 Rotor RPM Indicator 225
7.2.3 Torque Measurement 226
7.2.4 Electrical Output Measurement 227
7.3 Field Test – Trial Run 227
7.4 Wind Turbine Performance Prediction- Trial Run 231
(Temporary Stand)
7.4.1 Start-up Characteristic 231
7.4.2 Maximum Torque Transmitted 231
7.4.3 Wind Direction Response and Over-speed 232
Control Mechanism
7.4.4 Rotor Revolution Totaliser 232
7.4.5 Simulation of Data Collection Procedure 233
7.5 Actual Field Test to Obtain Wind Turbine Performance 234
8 RESULTS AND DISCUSSION ON WIND TURBINE 237
SYSTEM TESTS
8.1 “Wind” Generation from Indoor Test Rig 237
8.1.1 Results 237
8.1.2 Discussion on Average Wind Speed and Profile 239
(Indoor Test Rig)
8.2 Wind Turbine Rotor Performance Investigation by 241
Using Indoor Testing Facility
8.2.1 Full Size Delta Turbine (R=1.5m) 241
8.2.1.1 Test Results 241
8.2.1.2 Discussion 243
8.2.2 AE Main Rotor Blade (R=1.5m) 244
8.2.2.1 Test Results 244
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8.2.2.2 Discussion 246
8.2.3 Combination of AE Main Rotor Blades (B=3, 247
R=1.5m) and Delta Blades (B=3, R=0.9m)
8.2.3.1 Test Results 247
8.2.3.2 Discussion 249
8.3 Trial Run Observation and Measurement 250
8.4 Discussion of Component Design and Reliability 252
8.5 Start-up Performance of Wind Turbine Prototype 253
8.5.1 Observation, Measurements and Results 253
8.5.2 Discussion 254
8.6 Electricity Generation Capacity Test 255
8.6.1 Electrical Output, Wind Turbine Rotor 255
RPM and Wind Speed Measurements
8.6.2 Discussion 256
8.7 Wind Turbine Prototype Performance Comparison 258
8.7.1 Comparison of Wind Turbine Prototype 258
Performance in Design Stage, Indoor Fan Rig
Testing and Field Test
8.7.2 Comparison of Wind Turbine Prototype 258
Performance with Other Existing Wind
Turbine
8.8 Wind Turbine Prototype Performance Prediction with 260
Bigger Rotor Diameter and Better Matched Generator
9 CONCLUSION AND RECOMMENDATION 264
9.1 Conclusion 264
9.2 Recommendation and Future works 266
9.2.1 Indoor Testing Facility 266
9.2.2 Wind Speed Data, Test Site and Tower Height 267
9.2.3 Wind Turbine Design 267
9.2.4 Test Method 268
REFERENCES 269
xv
APPENDICES A – K 285 – 349
xvi
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Design tasks (Eggleston and Storddard, 1987) 19
2.2 The percentage frequency of various directions and speeds 32 for Mersing
2.3 The pratical aspects of some wind turbine rotors 50
(Hengeveld et al., 1978) 2.4 Properties of transmission devices 64
(Hengeveld et al., 1978) 2.5 Wind turbine-generator matching parameters 69
(Hengeveld et al., 1978) 3.1 Operating parameters of small wind turbine 99
(Wood, 2002) 4.1 Estimated power at output shaft 130 4.2 Iteration process to obtain a and a’ 153 4.3 Strip theory calculation of rotor blade torque and power 154
from every radial station 5.1 Wind turbine prototype cost 201 5.2 Price list of Windstream Power System 202 8.1 The point values of average velocity collected at 238
18 points for Type A and B arrangement 8.2 Type A and Type B 18-point average wind 240
speed calculation 8.3 Comparison of shaft power gained with the increase in 262 rotor diameter at same wind speed
xvii
LIST OF FIGURE
FIGURE NO TITLE PAGE
1.1 The December 19, 1976 Argo Merchant oil spill off 2 Nantucket, Massachusetts (Erickson, 1992)
1.2 The pollution issues at coastal areas of Pengerang, Johor, 2 Malaysia (China Press, June 26, 2005)
1.3 Twenty wind turbines in a 20-meters-tall honeycomb- 3
shaped configuration generate electricity in Kitahiyama, northern Japan (New straits Times, April 20, 1999)
1.4 Research methodology for wind turbine prototype design 12 2.1 Wind turbine design process (Park, 1981) 16 2.2 Typical remote area daily load profile 20
(Synergy Power Corporation, 1998) 2.3 Typical daily load curve (Lam and Moeller, 1996) 21 2.4 A conservative estimate of the power output from 25
each square metre of area swept by a wind rotor (Hengeveld et al., 1978)
2.5 The monthly and annual mean hourly wind speeds 26 during the day (Hengeveld et al., 1978) 2.6 The power distribution curve, derived from Figure 2.5 26
with P = 0.1 x V3 (Hengeveld et al., 1978) 2.7 The velocity frequency curve (Hengeveld et al. 1978) 27 2.8 The energy frequency curve, derived from Figure 2.7, 28
with P = 0.1 V3 (Hengeveld et al,. 1978)
2.9 The velocity duration curve, derived from Figure 2.7 29 (Hengeveld et al., 1978)
xviii
2.10 The wind speed as a function of time 29 (Hengeveld et al., 1978)
2.11 (a) Mean wind speed for meteorological station in 30 Malaysia (Abas and Utama, 1993) 2.11 (b) Wind speed and energy distribution for Mersing 31
Meteorological Station (Abas and Utama, 1993)
2.12 (a) Senai wind speed frequency curve, 1995 33 (Weibull distribution)
2.12 (b) Senai wind speed cumulative frequency curve, 34
1995 (Weibull distribution) 2.12 (c) Senai wind speed 1995 – cumulative occurrence hours 34 2.13 Balai Cerapan, UTM 35 2.14 Anemometer mounted on top of post 36 2.15 Pen-paper recorder 36 2.16 Wind speed chart from pen-paper chart (Balai Cerapan UTM) 36 2.17 Site assessment (McGuigan, 1978) 41 2.18 The increase in wind speed and energy gained by 42
increasing tower height (McGuigan, 1978)
2.19 Wind speed profile over different terrain (Park, 1981) 42 2.20 UTM map for site selection 44 2.21 Balai Cerapan contour and test site location 44 2.22 Hand-held GPS device 45 2.23 Test site 46 2.24 Power coefficient versus tip speed ratio for various 48
wind turbines (Warne, 1983)
2.25 The power coefficient of wind turbine rotors as a 48 function of tip speed ratio (Hengeveld et al., 1978)
2.26 The torque coefficient of wind turbine rotors as 49
a function of tip speed ratio (Hengeveld et al., 1978) 2.27 Main turbine type (Heier, 1998) 54
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2.28 Hub types (Heier, 1998) 58 2.29 Wind machines (Heier, 1998) 46 2.30 Optimal rotor blade geometry for various numbers 59
of blades and design tip speed ratio (Heier, 1998) 2.31 Production of blade shape (Heier, 1998) 59 2.32 Airflow effects on the rotor blade (Heier, 1998) 60 2.33 Tail vane and moment arm (Gouriers, 1982) 61 2.34 Sankey diagram (Hengeveld et al., 1978) 63 2.35 A typical family of torque-speed curves for a 66
fixed pitch turbine(Warne, 1983)
2.36 Model wind turbine output vs. design wind speed 67 (Johnson, 1985)
2.37 PMG 100 generator characteristics 68 2.38 A simple method to measure the starting torque of a 71
generator (Hengeveld et al., 1978) 2.39 The response of two wind turbine rotors to a gust of wind 76
(Park, 1981) 2.40 Bosman poldermill - notice the position of the mast on 79
the blade (Dekker, 1977)
2.41 Claw-pole alternator (Bosch, 1998) 81 2.42 Low RPM permanent magnet DC generator 82
(Windstream Power System Incorporated, 2001) 2.43 The output current, I as a function of the 84
rotational speed of a dynamo and an alternator (Hengeveld et al., 1978)
2.44 The torque speed curve of a dynamo and an alternator 84 (Hengeveld et al., 1978)
2.45 The power output curve of a dynamo and an alternator 85
(Hengeveld et al., 1978) 2.46 The efficiency speed curve of a dynamo and an alternator 85
(Hengeveld et al., 1978)
xx
2.47 The idealised current-speed curve of a generator 85 equipped with a current limiting device (Hengeveld et al., 1978)
2.48 The idealised torque-speed curve of a generator 86
(Hengeveld et al., 1978) 2.49 The output current of a generator at fixed speed as a 86
function of field current (Hengeveld et al., 1978) 2.50 The torque speed curves of an alternator for different 87
values of the field current (Hengeveld et al., 1978) 2.51 Configuration of data acquisition system (Sahat, 1981) 89 2.52 Sensor location on WECS (Sahat, 1981) 90 3.1 Major components of a horizontal axis wind turbines 98
(Manwell et al., 2002) 3.2 Flow diagram for a wind turbine (Gustafsson et al., 1980) 101 3.3 Blade element velocity diagram (Gustafsson et al., 1980) 102 3.4 Blade element force coefficients (Gustafsson et al., 1980) 104
3.5 Blade element annular ring (Gustafsson et al., 1980) 105 3.6 Rotor blade element (Hunt, 1981) 106
3.7 Velocity diagram for a rotor blade element (Hunt, 1981) 107 3.8 Iteration procedure to be performed for each radial 110
station (strip theory) 3.9 Lift and drag on an aerofoil section (Warne, 1983) 111 3.10 Variation of lift coefficient with angle of attack for 113
NACA 0012 and 4421 (Warne, 1983) 3.11 Variation of drag coefficient with lift coefficient for 113
NACA 0012 and 4421 (Warne, 1983) 3.12 Miley/Eppier low Reynold number model, NACA-0012 115
(Musial and Cromack, 1988) 3.13 High AOA airfoil performance results, 115
V=26m/s; Re=650,000 (Butterfield et al., 1992) 3.14 Flow model (Kussmann, 1981) 116
xxi
3.15 Airflow and forces at blade element (Kussmann, 1981) 117 3.16 Airfoil section’s lift and drag (Kussmann, 1981) 118
3.17 L/D ratio and blade number effects (Kussmann, 1981) 119 3.18 Blade twist distribution (Kussmann, 1981) 120 3.19 Blade chord distribution (Kussmann, 1981) 121 3.20 Rotor blade planforms (Kussmann, 1981) 121
3.21 Power coefficient vs. TSR for different blade 121
planforms (Kussmann, 1981) 3.22 Velocities for blade element at radius r 124
(Wood, 2002)
3.23 Lift and drag at high incidence- for infinite aspect ratio 125 (Wood, 2002)
4.1 Wind turbine design process 129 4.2 Permanent magnet DC generator – stock no. 443700 131
(Windstream Power System Incorporated, 2001)
4.3 The performance curve of 443700 permanent 132 magnet DC generator (Windstream Power System Incorporated, 2001)
4.4 Delco Remy BC 14-12 V NEO, 1100 62P-37A 133
performance curve (Hengeveld et al. 1978)
4.5 Automobile alternator 12V, 70A 134 (for Toyota Camry car)
4.6 Wind turbine rotor arrangement 136 4.7 Airfoils used in wind small turbine application 140
(Selig et al., 1997)
4.8 HK 8556 airfoil (Simons, 1987) 141 4.9 AE blade airfoil used in main rotor blade 141 4.10 AE airfoil modeled in GAMBIT and analysed 142
using FLUENT 4.11 CI and Cd of AE aerofoil 143
xxii
4.12 The maximum obtainable power coefficient in the 144 ideal case (Dekker, 1977)
4.13 Starter blade design adapted from delta-turbine 145
(Kentfield, 1989) 4.14 The performance of 8-bladed Delta-turbine 145
(Kentfield, 1989)
4.15 The cut-out plan for Delta blade prototype before 146 bending (scaled down 0.6:1 model was used for starter rotor combined with AE main rotor)
4.16 Definition of length, angles and plan-form of 147
Mie vane (Shimize et al., 1992) 4.17 AE airfoil section for r = 0.7 R and 0.8 R 152 4.18 AE rotor blade cut-out plan (up-wind view) 155 4.19 Placement of main rotor arm 158 4.20 Part, constraints and force modeling on 160
COSMOS/WORKS 4.21 COSMOS/WORKS (FEA) analysis – tail unit 161 4.22 Over-speed control vane and boom 162 4.23 Components in over-speed control device 163 4.24 Control vane orientation in strong winds and 164
low winds conditions 4.25 Different in pressure on rotor area tends to yaw the 165
rotor 4.26 Diagram of wind speed direction and the moment 165
generated by rotor, blades, tail vane and control vane 4.27 70A Toyota alternator 166 4.28 The drive motor with rig designed for obtaining 167
torque-speed curve of the 70A Toyota alternator 4.29 Automotive alternator in the wind turbine system 167
assembly for field test 4.30 Load matching 168
xxiii
4.31 Torque-speed curve of wind turbine rotor 170 5.1 General arrangement of WECS prototype 171 5.2 Tower and foundation 172 5.3 Rotor blades: a) main rotor blade b) starter rotor blade 173 5.4 Tail fin 174 5.5 Over-speed control system – 174
a) fin and boom b) mounting to turntable c) fin surface deflection mechanism
5.6 Turntable 175 5.7 Drive shaft, belt-pulley RPM increaser and alternator 176 5.8 Slip-ring 176 5.9 (a) Turntable assembly 177 5.9 (b) Turntable platform 179 5.9 (c) Turntable base 179 5.9 (d) Turntable center core 180 5.9 (e) Taper roller bearing 180 5.9 (f) Turntable transmission shaft 181 5.9 (g) Turntable bearing cover 181 5.9 (h) Turntable core support 181 5.9 (i) Turntable bottom bearing cover 182 5.10 (a) Slip ring assembly 183 5.10 (b) Yawing portion of slip ring assembly 183 5.10 (c) Stationary portion (receiving terminal) of slip-ring 183
assembly 5.11 (a) AE main blade rotor 184 5.11 (b) Delta blades starter rotor 185
xxiv
5.11 (c) AE main blades rotor arm with flow divider 186 5.11 (d) Delta blades starter rotor arm 186 5.11 (e) Rotor hub 187 5.11 (f) Rotor hub assembly 187 5.11 (g) Rotor center shaft 188 5.11 (h) Strut wire holder 188 5.11 (i) Outer rotor strut (main rotor arm) 189 5.11 (j) Inner rotor strut (main rotor arm) 189 5.12 (a) Tail assembly 190 5.12 (b) Tail pivot 190 5.12 (c) Tail mounting 191 5.13 (a) Drive shaft 191 5.13 (b) Drive shaft bearing 192 5.13 (c) Belt tensioner 192 5.14 Tower foundation 193 5.15 Tower base design 194 5.16 Middle tower, lower tower and tower base 194 5.17 Assembly of upper tower (lower portion) and 195
middle tower 5.18 Top portion of upper tower / tower head 195 5.19 Tower erection 196 5.20 Mounting of middle tower to lower tower 196 5.21 Wind turbine prototype installed on temporary stand 197 5.22 RPM counter with sensor 198 5.23 Belt-pulley transmission system and alternator 198 5.24 Mounting of lifting hook to wind turbine prototype 199
xxv
5.25 Wind turbine prototype installation 200 6.1 Blade with HK 8556 airfoil profile 204
6.2 Wind tunnel test rig with Delta blades rotor model 204 6.3 3-bladed AE main rotor prototype (R=1.5m) without 205
tip-attach 6.4 3-bladed AE main rotor prototype (R=1.5m) with 206
tip-attach 6.5 3-bladed Delta blade rotor prototype 206 6.6 Fan-mounting rig with 13 fans 208 6.7 CAD modeling of indoor test rig 209 6.8 Moving rig with fans mounted on it 209 6.9 Moving rig height control mechanism 210
(with locking feature) 6.10 Fans location 210 6.11 Fan configurations in testing facility 212 6.12 Flow pattern of a typical circulator fan (Daly, 1979) 212 6.13 Point velocity at measurement plane (3.5 m from fan-plane) 213 6.14 Wind speed meters 218 6.15 Friction-rope brake 214 6.16 Load cell with its adaptor and mass loader 214 6.17 Load cell calibration 215 6.18 Wind speed measuring point (view from wind turbine 218
up-wind, fans at back) 6.19 Alternator and drive motor mounting on test rig 218 6.20 Fuji general purpose inverter (FVR-E9S) 218 6.21 TM-2011 tachometer 219 6.22 Instruments and electrical connection for measuring 219
battery charging current and voltage
xxvi
6.23 Schematic diagram of automotive alternator connection 220 and battery charging current and voltage measurement
6.24 Spring balance 221 7.1 2 round metal plates with 3 clamping screw holes to 223
increase the strength of rotor hub 7.2 3 extra inner rotor struts for increasing the rotor strength 223
7.3 A thin metal plate was mounted at r = 0.7R to increase 223
the blade rigidity in section wise (with extended smaller diameter rotor arm)
7.4 Platform and locking arm 224 7.5 Wind cup / wind transmitter 225 7.6 Wind speed measuring device (digital pitot-tube meter) 225 7.7 Multi-tester 225 7.8 Cam, micro switch and signal transmission cable 226 7.9 Push-pull gauge 226 7.10 Platforms for inspection and maintenance works 227 7.11 Alternator, slip-ring and electrical connection 228 7.12 Insulation sleeves 229 7.13 Over-speed control mechanism 229 7.14 Rotor blades and rotor arms 230 7.15 Strut wire holder 230 7.16 Tail boom mounting base 230 7.17 Drive shaft and belt-pulley speed increaser 232 7.18 Cover on turntable 233 7.19 Wind speed data measurement 234 7.20 Wind cup installation during field test 235 7.21 Battery charging current and voltage, and no. of 236
revolution signal transmission cable
xxvii
7.22 Wind cup transmission cable 236 7.23 Battery charging current and voltage, wind speed 236
and no. of revolution data measurement or displays
8.1 Velocity profile at rotor plane position for Type A and 239 B arrangement
8.2 3-bladed Delta rotor – data and result (performance curves) 242 8.3 Comparison between 3-bladed and 8-bladed Delta-turbine 243 8.4 Cp and CQ vs. TSR for AE blade rotor (main rotor) 245
8.5 The comparison of CP vs. TSR obtained from indoor 246
testing facility and blade element calculation (design condition), CP – Prediction (BET)
8.6 Performance characteristics of AE + Delta blades rotor 248 8.7 Comparison of the final rotor configuration with 249
the individual rotor blades contribution 8.8 Anemometer mounted on an extendable boom 254 8.9 Rotor rpm vs. wind speed (field test) 256 8.10 Load matching for 2 Amp current output 257 8.11 Comparison of wind turbine prototype performance 259
in design stage, indoor fan rig testing and field testing
8.12 Comparison of wind turbine generator performance 260
with existing wind generators in market 8.13 Performance characteristics of PMG 300 and load matching 261 8.14 Comparison of power output from wind turbines and wind 263 speed distribution (Mersing)
xxviii
LIST OF SYMBOLS
Achord - Blade area between bi and bo
Aring - Annulus area between bi and bo
AOA - Blade section angle of attack
a - Axial induction factor
a′ - Angular induction factor
B - Number of blade
bi - Inner station span / R
bo - Outer station span / R
Δb - Station span
c - Local blade chord
CD - Blade section drag coefficient
CF - Thrust coefficient
CL - Blade section lift coefficient
CP - Power coefficient
CP′ - Section power coefficient
CQ - Torque coefficient
Cq′ - Section torque coefficient
Cx or Ct - Blade section force coefficient (turbine plane)
Cy or Cn - Blade section force coefficient (axial)
D - Drag
G - Gear ratio
IF - Excitation current (field current)
IG - Output current of generator
i - Transmission ratio
L - Lift
ncut-in - Cut-in speed (rpm) of generator
xxix
nG - RPM of generator shaft
nr - RPM of wind turbine rotor shaft
Pin - Power input of generator
Pout - Power output of generator
Pshaft - Shaft power
Qshaft - Torque at the shaft of the wind turbine rotor
Qstart - Starting torque of wind turbine rotor
R - Radius of the rotor / tip radius
r - Rotor radii
T - Blade tangential force
TSR - Tip speed ratio
UG - Terminal voltage of the generator
u - Blade tangential speed
V - Wind speed
V1 - Wind speed at upstream of rotor or initial velocity
V2 - Wind speed through turbine rotor plane
V3 - Wind speed at downstream of rotor or final velocity
Vcut-in - Cut-in wind speed
Vcut-out - Cut-out wind speed
V∞ - Free stream wind speed
w∞ - Swirl velocity
α - Wind shear exponent
φ - Relative flow angle
ηB-P - Efficiency of belt-pulley
ηGr - Efficiency of gear
ηG - Efficiency of the generator
ηG (E) - Efficiency of the excitation of the generator
ηTr - Efficiency of the transmission (friction loss)
λ - Tip speed ratio
ρ - Density of the air
Ω - Turbine angular velocity
xxx
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Glossary of key terms 285 B1 Distribution of extreme winds over Malaysia 288 B2 Senai’s annual wind rose summary 291 B3 Senai’s surface wind data (year 1994, 1995 & 1996) 292 B4 Percentage frequency of various direction and speeds 295 - Mersing, Senai & Kuala Terengganu (1975 - 2002) B5 Senai wind speed and direction data (1995) 298 B6 Balai Cerapan wind speed data 312 C Parameters study on existing wind turbines 316 D1 Aerodynamic criteria of AE airfoil and comparison with
other similiar airfoil 320 D2 AE blade section geometry 322 D3 Strip theory calculation 327 E Wind turbine part and assembly 331 F Structural analysis on critical parts in wind turbine 336
prototype G Weight and balance 341 H Wind turbine prototype cost 342 I Load matching : PMG 100 344 J Over-speed control calculation 346
xxxi
K Papers published 349
CHAPTER 1
THESIS INTRODUCTION
1.1 Introduction
This thesis describes the study of low cost, medium rotational speed
(optimum tip speed ratio, TSRopt = 2.1 – 4.6), small scale stand-alone wind turbine
for electrical power generation in low wind speed regions (Vave < 2.50 m/s) like
Malaysia. As we know, wind energy has long been recognised as a potential source
of free, clean and inexhaustible energy; and it could play an important role in
contributing to small amount of energy requirements at the rural areas. The cost
effectiveness of a wind energy conversion system (WECS) is a function of low initial
costs, good energy production and high competing ‘fuel’ cost.
Malaysia is situated at equatorial zone and experiences low speed wind belt
consisting of Southwest and Northeast Monsoons a year. Most of the areas in
mainland experience low (V∞ < 4m/s for more than 80% of total hours) and unsteady
wind speeds. As a result, most of the existing wind generators (Vrated = 9 - 15 m/s)
are not suitable for Malaysian applications since they are designed for high wind
speeds which prevail in the USA and Europe. However, there is a potential for wind
energy especially at the coastal areas and islands off the east coast of Peninsular
Malaysia, if a suitable wind turbine design could be found. Sia (August 01, 1995)
has reported that the wind speeds in islands of Perhentian, Redang and Tioman reach
up to 5 or 6 m/s during monsoon months. So, wind energy could be an economically
viable generation of electricity for isolated areas far away from national grid system,
2
for the cost of laying electricity transmission cables and delivering fuel. Also, wind
energy is particularly suitable for islands where pollution is a crucial issue. This
technological innovation could safeguard the environment and curb overexploitation
of country’s rich natural resources. Oil spills are by far the most damaging of all
coastal and river pollution. Major oil spills such as The December 19, 1976 Argo
Merchant oil spill off Nantucket, Massachusetts (Figure 1.1), spillage of massive
quantities of oil in the Persian Gulf as a results of the eight-year Iran-Iraq war and
1991 Persian Gulf War have led to disastrous ecological consequences (Erickson,
1992). Sea pollution due to oil sludge also occurred at coastal areas of Pengerang,
Johor, Malaysia (Figure 1.2). It has caused an impact on the fishermen and was
reported by China Press (June 26, 2005).
Figure 1.1 : The December 19, 1976 Argo Merchant oil spill off Nantucket,
Massachusetts (Erickson, 1992)
(a) (b)
Figure 1.2 : The pollution issues at coastal areas of Pengerang, Johor, Malaysia
(China Press, June 26, 2005).
3
Before significant benefits from the wind power could be realised, many
technological and environmental problems had to be solved. Therefore, sufficient
knowledge in WECS design, location of site, wind resources and load matching has
to be gained. The use of small and medium size WECS rated at several hundreds of
watts or a few kilowatts is gaining popularity for domestic and for small business
and commercial use. According to Shepherd and Shepherd (1998), economic
operation of small wind powered generators requires average wind speeds of 12 mph
(5.36 m/s), being less stringent than for large system (requires higher cut-in speed,
complicated drive train and control system). In Malaysia, Sia (August 01, 1995)
reported that new technology can profitably harness winds as low as 3 m/s.
According to the study on the potential of wind energy in Indonesia done by
Notodisuryo (1990), wind velocity could reach more than 4 m/s in Indonesia. The
speed is considered as sufficient for moving a small scale wind turbine which
generates electricity ranging from 250 to 500 watts in villages located along the coast
and islands. Moreover, the study of small wind turbine does not mean just for small
amount of energy production. New Straits Times (April 20, 1999) has reported that
twenty wind turbines in a 20 meters tall honeycomb-shaped configuration was used
in Japan, and it was claimed that the cost of building and running this unique wind
turbine generator is lower than that for a similar output large single wind generator
(Figure 1.3).
Figure 1.3 : Twenty wind turbines in a 20-meter-tall honeycomb-shaped
configuration generate electricity in Kitahiyama, northern Japan (New Straits Times,
April 20, 1999)
4
With only one 150 kW WECS installed at Pulau Layang-Layang, wind power
technology is still considered to be in the initial stages of development in Malaysia.
The research on wind energy at Universiti Teknologi Malaysia (UTM) has been
started at Faculty of Mechanical Engineering (FKM), UTM since 1988. Most of the
existing wind turbines were designed for the requirement of extreme wind speeds
and involved high-tech design and fabrication. So, the design of the wind turbine for
Malaysian wind conditions must be changed for better matching and optimised for
higher output and/or longer operation hour at lower wind speeds. In this project, the
design, fabrication, testing of a low cost wind turbine for electrical power generation
(for lighting), which is suitable for Malaysian wind conditions has been carried out.
The viability of the use of wind turbines to generate electricity is primarily
dependent on its ability to operate under low wind speeds and the capital cost of the
installation. So, the entire design concept aimed at good start-up behaviour with
acceptable performance criteria, simplicity, reliability, automatic, relatively
maintenance-free service and low cost in order to suit the requirements of the low-
income groups in off the grid areas of developing countries such as Malaysia.
1.2 Problem Statement
Wind energy is one of the most available renewable energy in addition to
solar and hydro energy. As reported by Xinhua in The Star (October 19, 1999), wind
energy could provide 10% of the world’s electricity requirement by 2020. The wind
driven systems produce no pollutants and are environmentally safe. Synergy Power
Corporation (1998) reported that eighty percent of the world’s landmass has winds
less than 5 m/s. Due to its geographical location, the overall potential of wind
energy in Malaysia is not very promising. In general, maximum surface wind is 13
m/s and percentage of calm period (wind speeds < 0.3 m/s) is 20% to 50% depending
on location (Abdul Majid Ismail, 2001). So, the main problem that hinders the
progress of wind energy in Malaysia is the low wind speed. However, some
locations (especially islands and coastal areas) could be suitable for wind power
generation –‘wind gate’. Some studies performed by UM, SIRIM, UPM and USM
on the wind energy since 1983 indicate that some strategic places in the East Coast
5
of Peninsular Malaysia have sufficient wind energy for utilisation (Chong and
Mathews, 2001). But, a lot of issues need to be considered related to its remoteness
in design stage (transportation, routine maintenance, weight and size of components,
assembly and installation method, etc.).
Since most of wind energy development has been encouraged by the market
stimulation in the developed world, primarily the Europe and USA, most of the wind
turbines were designed for the requirement of high wind speeds (V∞ > 6 m/s) which
prevail in these regions. For low wind speeds regions like Malaysia, a different rotor
design might be used to harness the wind power in a wide range of 2.0 m/s to 12 m/s
wind speeds (to avoid the incorrect matching between the turbine design speed and
the wind energy available). These wind turbines will also be designed for easy
transportation (suitable for remote areas and islands), easy to erect and lower
survival wind speeds, i.e. according to the wind speed in lower wind speed region
(with a lower capital cost as a result). In order to generate electricity in low wind
speeds (V∞ less than 4 m/s is considered low for wind turbine generator application),
the wind turbine must have high starting torque coefficient while still attaining
sufficient running speeds.
It is also recognised that high cost (the total cost to purchase and install the
complete wind energy system in order to provide desired operation of the system,
including wind turbine, tower, power storage, control system, connections,
installation cost, etc.) is the greatest barrier to the use of WECS. These costs must be
reduced in order to make wind power cost-competitive with other power sources. A
more robust design is also required to reduce the life cycle cost. However, it will
further decline because of technical advance in wind machines, cost-cutting
improvements in manufacturing techniques and environmental concerns. Moreover,
wind power technology is straightforward (does not involve sophisticated processing
of material, etc.). Because of that advantage, developing countries with their
relatively cheap labour, might turn to building their own manufacturing capacity in
the technology (Jayadec, 1995). The cost of wind energy is reduced if higher wind
speeds available. According to Manwell et al. (2002), site with power density of 400
W/m2 (V∞= 8.5 m/s) is categorised as good site. For the capacity of 500 Watts and
6
the average wind speed of 5 m/s, the electricity cost is around US$ 0.63 per kWh,
and if the average wind speed increases to 6 m/s, the cost of electricity will be about
US$ 0.29 per kWh (Notodisuryo, 1990).
The other important criterion that needs to be considered is the level of
existing technology. The technology used must be able to be handled by local
people (installation, operating, maintenance and repairing), and also the components
/ parts of the WECS could be obtained easily. Furthermore, the simple design also
means that the technology could be transferred and wind turbine could be built in
many countries utilising local material and manufacturing capabilities.
Another problem for the immediate economic development of wind energy is
the competition from the very low-priced electricity usually available from national
grid. So, at this moment wind energy is most suitable and viable to be applied at the
islands where it is far away from main electricity grid and pollution is a critical issue.
1.3 Objective, Aim and Importance of Research
The objective of this research is to build a medium rotational speed wind
turbine in order to generate small scale electrical power in Malaysian wind
conditions. This involved designing, fabricating, testing and determining (blade and
rotor configuration) a suitable wind turbine that is able to perform up to expectation
at low wind speeds.
At this moment, there is still lack of awareness of the possibility of
harnessing power from the wind, especially for our rural areas. This project is aimed
to harness the wind energy available in Malaysia by producing a wind turbine that
could be coupled with other existing WECS components (power transmission
system, power generation system, power storage system, etc. that are available
locally) for the Malaysian wind conditions. The power generated could be used in
remote areas (far from main national grid and electricity distribution would be of
prohibitive cost or would never be connected to the network). The main application
7
of this WECS is to supply power for battery charging and lighting system and other
applications such as powering communication network, lighthouse and beacon.
Taking into account budgetary constraints and inadequacy of technological
infrastructure, a progressive development approach has been adopted for the
development of small wind turbine for battery charging. The wind turbine
construction should be more robust and relatively simple. The WECS designed is
also aimed for easy transportation, installation, operation and management (highly
skilled person and advanced technology are not required). The capital, operating and
maintenance costs of the WECS designed must be affordable. Moreover, the
technique, parts and components used must be easily obtained or fabricated locally.
Thus, it is decided to use commercially available automobile alternator in the
experimental prototype although low speed permanent magnet generator could be a
better choice.
Besides, this research also provided a better understanding towards the
knowledge, technical know-how and performance characteristics of wind turbine
(coefficient of power, coefficient of torque, load matching, starting torque, cut-in
speed, etc.) through wind tunnel tests, indoor testing and field tests conducted on
wind turbine models and prototypes. The prototype built has provided a design
concept to produce a wind turbine locally that is able to meet the requirements
defined. The performance could be improved with further refinement and better
matching could be done in future research (with particular application and site). So,
the development of the small horizontal axis wind turbine is intended to meet the
need for rural applications (with small amount of energy requirement), as well as to
build up understanding and appreciation required for the development of larger and
complex systems.
To sum up; an efficient (adapted to Malaysian wind conditions) and cost
effective WECS is aimed for, with the design and production technique developed
locally. The performance must be optimised and competitive with existing small
wind turbines in market (Appendix C) in terms of total operating hour and energy
gained if both wind turbines operate in Malaysian wind conditions. The long-term
goal is the proliferation of wind energy applications in rural areas and the
8
establishment of wind farm, capable of supplying local power to remote areas.
1.4 Research Scope and Methodology
This research has been divided into several parts / phases:
a) To perform literature review (parameter study, design approach, rotor blade
aerodynamic design, component and structural design, test method and recent
development).
b) To obtain and process the wind data recorded at UTM sites (Fakulti
Kejuruteraan Awam, FKA and Balai Cerapan) and Senai Meteorological
Station.
c) To identify, design and fabricate a low cost medium rotational speed wind
turbine (model and prototype) and the supporting structure that is suitable for
small scale electrical power generation (less than 1 kW output).
d) To design and construct the indoor testing facility, and to prepare the test
parameter measuring equipment.
e) To test the wind turbine model and prototype by using wind tunnel and
indoor testing facility, and evaluate the wind turbine rotor performance.
f) To conduct survey on suitable power generation system, power storage and
lighting system, and perform load matching.
g) To conduct site testing of WECS (feasibility and functional test at real
conditions).
h) Wind turbine performance data collection and analysis.
Phase I involved the feasibility study and development of conceptual design.
It was initiated with the parameter study of existing wind turbines and generators in
market (rotor diameter, cut-in speed, rated power, rotational speed, etc.) – Appendix
C. The wind speed data was obtained from secondary resources, e.g. the average
wind speed data furnished by Malaysian Meteorological Departments for weather
stations in Malaysia (e.g. Senai wind speed data in 1995). Wind speed data from
other publications was also reviewed to understand the wind variation in Malaysia.
The evaluation of wind resources and calculation of wind energy at the selected sites
9
(Senai, Mersing and UTM Skudai) were also carried out. This information was used
to study the feasibility of using wind turbine system in Malaysia. The machine /
product requirements such as machine type and configuration, performance,
application, estimated costs and other specifications were outlined. The design
specification and conceptual design were developed for the machine functionality
and its general arrangement. In this project, the energy demand was not specified
since the wind turbine was designed for testing purpose only.
Phase II was the preliminary design stage and it involved building and testing
experimental models. The rotor blades models and wind tunnel test rig were
designed and fabricated. The wind tunnel test on the 1: 5 scale-down models has
been conducted at the wind tunnel in Termo Lab., FKM, UTM. The results from
wind tunnel tests are useful to compare the performance of various rotor blades
combination, and they could be used to select optimal solution. But, the results were
not encouraging due to scale-down factors (Reynold number and bearing friction).
After the tests, wind turbine type, preliminary system and sizing were established.
After performing load matching, a wind turbine rotor with 3 m diameter was
designed to drive an automobile generator through belt-pulley RPM increaser (initial
intention was a low speed permanent magnet generator (PMG) driven through gear
box or a direct drive PMG). A survey on simple battery storage and lighting was
carried out in order to obtain suitable one for testing purpose. After the WECS
design was conceptualized, the detail design of every component could be
performed.
In phase III which is the detailed machine / product design stage, the detail of
functional components and mechanism were created and analysed through CAD,
drawing, calculation and computer software simulation. Some of the critical
components of the wind turbine were designed and analysed based on aerodynamics
and structural analysis. The selection procedure of airfoil section and rotor blade
design was performed, based on the information gained from literature review. In
aerodynamic design; airflow, airfoil selection, blade twist, torque and power
coefficient were considered. An existing Delta-wing rotor with maximum torque
coefficient at zero tip speed ratio was chosen as starter rotor to aid start-up
performance. Suitable airfoil for main rotor blade was reviewed (HK8556) for
10
predicted Reynold number. The simplified airfoil profile (AE airfoil) designed was
analysed using GAMBIT and FLUENT software. The aerodynamic design and
performance analysis of the innovative rotor blade have been carried out. The
tangential force and rotor drag prediction was based on the blade element momentum
theory (BEM) / strip theory. In order to have a compromise between good starting
behaviour and reasonable rotational speed, 6-bladed wind rotor with the combination
of existing Delta blades and innovative blades (AE blades) was obtained. The overall
system efficiency was then estimated and the rotor size (diameter) was calculated.
Since the aerodynamics and structural analysis are related, it is more practical to
develop them together. The various loads on the rotor and shaft were examined, and
each member was designed to withstand the applied loads. COSMOS/Works
software has been used to aid the structural analysis. The system design was also
analysed for possible component interface, fabrication and operation problems. The
various efficiencies and performance characteristics (coefficient of power and
torque) were evaluated, and then the system efficiency was re-estimated. This was a
challenging and time-consuming task because of the many complex
interrelationships involved.
Phase IV involved the fabrication, installation and indoor testing of wind
turbine prototype. A full-scale prototype (3 m diameter) was fabricated for indoor
testing and field testing. Specialised tools and fixtures were also required to assist
the installation, monitoring, maintenance and testing purposes. A low cost indoor
test rig has been built to generate “wind” for indoor testing of wind turbine
prototype. The purpose of the design and fabrication of this testing facility is to
obtain some important aerodynamic characteristics of the wind turbine rotors
designed, i.e. power coefficient, CP and torque coefficient, CQ at different tip speed
ratio (TSR), before field testing. The starting behaviour of the wind turbine rotor
could also be studied, by matching the wind turbine performance obtained with the
applied load (generator’s characteristics curve). This test rig could provide a suitable
testing facility (low cost and easy-to-assemble) for low wind speed wind turbine
prototype. This indoor testing facility could eliminate some problems that would be
faced in actual field tests. The results of the measurements have produced the
necessary data for the evaluation of the rotor blade performance. Comparison of the
performance results from this test method with design conditions (using BEM),
11
indicates that this indoor testing facility can be used for wind rotor design
verification and optimisation. For load matching purpose, the output power (shaft
power) at various TSR and wind speed could be matched with the generator load
curve.
In phase V, field test was carried out and it involved a lot of preparation
works (building of tower and foundation, tower erection, maintenance platform,
instrument set up, etc.). A suitable site for conducting field test was selected at Balai
Cerapan, UTM Skudai based on the criteria set. The wind turbine design was
tweaked and enhanced for better strength before field testing. The wind speed
measurement equipment was set up for data recording. The wind speed data would
be compared with the data from Senai Meteorological Station. The supporting
structure / tilted tower was designed and fabricated for wind turbine installation.
This prototype has been tested at Balai Cerapan UTM to study the feasibility of
using wind power for electrical power generation. The measuring instruments
(revolution counter, anemometer, slip ring and wiring for transmitting electrical
signal from alternator) were mounted on wind turbine structure. The signals
produced were transmitted to recorders / displays. The measured parameters were
wind speed, number of revolution in certain period (RPM) and output power (battery
charging ampere and voltage). The results obtained could be compared with
theoretical prediction / design parameters. In field trial, the wind turbine was also
monitored for its component strength and yaw response. In addition, the fabrication
and maintenance costs of WECS have also been estimated.
Above approach was implemented in order to realise the localisation of wind
turbine technology in Malaysia and the flow chart was given in Figure 1.4. General
ideas and knowledge for completing a wind turbine have been outlined, with further
refinement in every single stage could be done in future.
12
Figure 1.4 : Research methodology for wind turbine prototype design
Evaluate application and energy need
Collect and review wind data, and site survey
Feasibility study and conceptual design - parameter study of wind generators, machine requirements
(type, configuration, performance specification and cost)
Preliminary design – building and testing of experimental models to obtain optimal configuration
Determine wind turbine type, preliminary system and rotor size for development and testing purpose
Airfoil selection, detail design of rotor blade and
configuration, and hardware selection
Structural analysis of rotor components, drive train, control system
and electrical transmission designs
Evaluate system efficiency and cost
Evaluate energy conversion measures and load matching
Refine system design
Evaluate overall design (component interference, fabrication, assembly
and operational problem)
Fabrication and assembly of wind turbine prototype
Design, fabrication and installation of
indoor testing facility
Indoor testing of wind turbine prototype and rotor performance evaluation
Measuring equipment set-up
for field test Field testing – rotor RPM, wind
speed and electrical output measurement. Monitor component
strength and yaw response
Final system design
269
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