Photovoltaic Power System Modeling, Design, and Control

Photovoltaic Power System: Modelling, Design and Control is an essential reference with a practical approach to photovoltaic (PV) power system analysis and control. It systematically guides readers through PV system design, modelling, simulation, maximum power point tracking and control techniques making this invaluable resource to students and professionals progressing from different levels in PV power engineering.

The development of this book follows the author's 15-year experience as an electrical engineer in the PV engineering sector and as an educator in academia. It provides the background knowledge of PV power system but will also inform research direction.

Key features:

• Details modern converter topologies and a step-by-step modelling approach to simulate and control a complete PV power system.
• Introduces industrial standards, regulations, and electric codes for safety practice and research direction.
• Covers new classification of PV power systems in terms of the level of maximum power point tracking.
• Contains practical examples in designing grid-tied and standalone PV power systems.
• Matlab codes and Simulink models featured on a Wiley hosted book companion website.

WEIDONG XIAO, The University of Sydney, Australia

Weidong Xiao is an Associate Professor within the University of Sydney's School of Electrical and Information Engineering. His research interests include PV power systems, power electronics, dynamic systems and control, and industry applications.

Preface xiii

Acknowledgments xvii

About the companion website xix

1 Introduction 1

1.1 Cell, Module, Panel, String, Subarray, and Array 2

1.2 Blocking Diode 5

1.3 Photovoltaic Cell Materials and Efficiency 6

1.4 Test Conditions 7

1.5 PV Module Test 8

1.6 PV Output Characteristics 9

1.7 PV Array Simulator 12

1.8 Power Interfaces 13

1.9 Standalone Systems 13

1.10 AC Grid-connected Systems 18

1.11 DC Grid and Microgrid Connections 19

1.12 Building-integrated Photovoltaics 21

1.13 Other Solar Power Systems 22

1.14 Sun Trackers 23

Problems 24

References 24

2 Classification of Photovoltaic Power Systems 25

2.1 Background 25

2.2 CMPPT Systems 26

2.2.1 Power Loss due to PV Array Mismatch 29

2.2.2 Communication and Data Acquisition for CMPPT Systems 32

2.3 DMPPT Systems at PV String Level 36

2.4 DMPPT Systems at PV Module Level 37

2.4.1 Module-integrated Parallel Inverters 37

2.4.2 Module-integrated Parallel Converters 39

2.4.3 Module-integrated Series Converters 40

2.4.4 Module-integrated Differential Power Processors 40

2.4.5 Module-integrated Series Inverters 41

2.5 DMPPT Systems at PV Submodule Level 42

2.5.1 Submodule-integrated Series Converters 42

2.5.2 Submodule-integrated Differential Power Processors 43

2.5.3 Isolated-port Differential Power Processors 44

2.6 DMPPT Systems at PV Cell Level 44

2.7 Summary 45

Problems 46

References 46

3 Safety Standards, Guidance and Regulation 49

3.1 Certification of PV Modules 49

3.2 Interconnection Standards 51

3.3 System Integration to Low-voltage Networks 55

3.3.1 Grounded Systems 55

3.3.2 DC Ground Fault Protection 56

3.3.3 Voltage Specification 56

3.3.4 Circuit Sizing and Current 58

3.3.5 Cable Selection 58

3.3.6 Connectors and Disconnects 59

3.3.7 Grid Interconnections through Power Distribution Panels 59

3.3.8 Marking 60

3.4 System Integration to Medium-voltage Network 60

3.4.1 Active Power Throttling 61

3.4.2 Fault Ride-through 61

3.4.3 Reactive Power Support 62

3.5 Summary 63

Problems 63

References 64

4 PV Output Characteristics and Mathematical Models 65

4.1 Ideal Single-diode Model 68

4.1.1 Product Specification 68

4.1.2 Parameter Identification at Standard Test Conditions 69

4.1.3 Variation with Irradiance and Temperature 71

4.2 Model Accuracy and Performance Indices 75

4.3 Simplified Single-diode Models 78

4.3.1 Parameter Identification: Part One 79

4.3.2 Parameter Identification: Part Two 81

4.3.3 Variation with Irradiance and Temperature 87

4.4 Model Selection from the Simplified Single-diode Models 88

4.5 Complete Single-diode Model 91

4.6 Model Aggregation and Terminal Output Configuration 92

4.7 Polynomial Curve Fitting 95

4.8 Summary 99

Problems 100

References 101

5 Power Conditioning 103

5.1 PV-side Converters 104

5.1.1 PV Module for Case Study 105

5.1.2 Buck Converter 105

5.1.3 Full-bridge Isolated Transformer DC/DC Converter 110

5.1.4 Boost Converter 115

5.1.5 Tapped-inductor Boost Topology 119

5.1.6 Buck–Boost Converter 122

5.1.7 Flyback Converter 126

5.2 Battery-side Converter for DC/DC Stage 130

5.2.1 Introduction to Dual Active Bridges 130

5.2.2 Discharge Operation 131

5.2.3 Charging Operation 135

5.2.4 Zero Voltage Switching 139

5.3 DC Link 142

5.3.1 DC Link for Single-phase Grid Interconnection 143

5.3.2 DC Link for Three-phase Grid Interconnections 145

5.4 Grid-side Converter for DC/AC Stage 147

5.4.1 DC to Single-phase AC Grid 147

5.4.2 DC to Three-phase AC Grid 151

5.4.3 Reactive Power 153

5.5 Grid Link 154

5.5.1 L-type for Single-phase Grid Connections 154

5.5.2 L-type for Three-phase Grid Interconnections 155

5.5.3 LCL-type Filters 157

5.5.4 LC-type Filters 160

5.6 Loss Analysis 160

5.6.1 Conduction Loss 161

5.6.2 High-frequency Loss 163

5.7 Conversion Efficiency 165

5.8 Wide Band-gap Devices for Future Power Conversion 165

5.9 Summary 167

Problems 169

References 171

6 Dynamic Modeling 173

6.1 State-space Averaging 173

6.2 Linearization 174

6.3 Dynamics of PV Link 175

6.3.1 Linearization of PV Output Characteristics 175

6.3.2 Buck Converter as the PV-link Power Interface 176

6.3.3 Full-bridge Transformer Isolated DC/DC as the PV-link Power Interface 180

6.3.4 Boost Converter as the PV-link Power Interface 182

6.3.5 Tapped-inductor Topology as the PV-link Power Interface 184

6.3.6 Buck–boost Converter as the PV-link Power Interface 186

6.3.7 Flyback Converter as the PV-link power Interface 188

6.4 Dynamics of DC Bus Voltage Interfaced with Dual Active Bridge 189

6.5 Dynamics of DC Link for AC Grid Connection 192

6.5.1 Single-phase Connection 192

6.5.2 Three-phase Connection 194

6.6 Summary 195

Problems 196

References 197

7 Voltage Regulation 199

7.1 Structure of Voltage Regulation in Grid-connected PV Systems 199

7.2 Affine Parameterization 201

7.3 PID-type Controllers 202

7.4 Desired Performance in Closed Loop 205

7.5 Relative Stability 206

7.6 Robustness 208

7.7 Feedforward Control 209

7.8 Voltage Regulation in PV Links 210

7.8.1 Boost Converter for PV Links 210

7.8.2 Tapped-inductor Topology for PV Links 213

7.8.3 Buck Converter as the PV-link Power Interface 214

7.8.4 Buck–boost Converter as the PV-link Power Interface 216

7.8.5 Flyback Converter as the PV-link Converter 218

7.9 Bus Voltage Regulation for DC Microgrids 220

7.10 DC-link Voltage Regulation for AC Grid Interconnections 221

7.10.1 Single-phase Grid Interconnection 222

7.10.2 Three-phase Grid Interconnection 226

7.11 Sensor, Transducer, and Signal Conditioning 227

7.12 Anti-windup 230

7.13 Digital Control 236

7.13.1 Continuous Time and Discrete Time 240

7.13.2 Digital Redesign 240

7.13.3 Time Delay due to Digital Conversion and Process 243

7.14 Summary 245

Problems 246

References 247

8 Maximum Power Point Tracking 249

8.1 Background 249

8.2 Heuristic Search 252

8.3 Extreme-value Searching 255

8.4 Sampling Frequency and Perturbation Size 257

8.5 Case Study 258

8.6 Start-stop Mechanism for HC-based MPPT 261

8.7 Adaptive Step Size Based on the Steepest Descent 264

8.8 Centered Differentiation 267

8.9 Real-time System Identification 270

8.9.1 Recursive Least Squares Method 270

8.9.2 Newton–Raphson Method for MPP Determination 272

8.9.3 Forgetting Factor 272

8.10 Extremum Seeking 273

8.11 Multiple Power Peaks and Global MPPT 276

8.12 Performance Evaluation of MPPT 277

8.12.1 Review of Indoor Test Environment 277

8.12.2 Review of Outdoor Test Environments 278

8.12.3 Recommended Test Benches for MPPT Evaluation 279

8.12.4 Statistical Paired Differential Evaluation 280

8.13 Summary 281

Problems 283

References 284

9 Battery Storage and Standalone System Design 285

9.1 Batteries 287

9.1.1 Battery Types 288

9.1.2 Battery Terminology 291

9.1.3 Charging Methods 292

9.1.4 Battery Mismatches and Balancing Methods 295

9.1.5 Battery Characteristics and Modeling 300

9.1.6 Battery Selection 308

9.2 Integrating Battery-charge Control with MPPT 308

9.3 Design of Standalone PV Systems 309

9.3.1 Systems without Significant Energy Storage 309

9.3.2 Systems with Significant Energy Storage 311

9.4 Equivalent Circuit for Simulation and Case Study 316

9.5 Simulation Model to Integrate Battery-charging with MPPT 317

9.6 Simulation Study of Standalone Systems 318

9.6.1 Simulation of PV Array 318

9.6.2 Short-term Simulation 319

9.6.3 Medium-term Simulation 321

9.6.4 Long-term Simulations 325

9.6.5 Very-long-term Simulations 328

9.7 Summary 329

Problems 331

References 332

10 System Design and Integration of Grid-connected Systems 333

10.1 System Integration of Single-phase Grid-connected System 335

10.1.1 Distributed Maximum Power Point Tracking at String Level 335

10.1.2 Distributed Maximum Power Point Tracking at PV Module Level 337

10.2 Design Example of Three-phase Grid-connected System 340

10.3 System Simulation and Concept Proof 343

10.3.1 Modeling and Simulation of PV String 344

10.3.2 Modeling and Simulation of DC/DC Stage 345

10.3.3 Modeling and Simulation of DC/AC Stage 349

10.3.4 Overall System Integration and Simulation 351

10.4 Simulation Efficiency for Conventional Grid-connected PV Systems 351

10.4.1 Averaging Technique for Switching-mode Converters 353

10.4.2 Overall System Integration and Simulation 354

10.4.3 Long-term Simulation 357

10.5 Grid-connected System Simulation Based on Module Integrated Parallel Inverters 359

10.5.1 Averaged Model for Module-integrated Parallel Inverters 359

10.5.2 Overall System Integration and Simulation 362

10.6 Summary 365

Problems 366

References 366

Index 367

The New copy of this book will include any supplemental materials advertised. Please check the title of the book to determine if it should include any access cards, study guides, lab manuals, CDs, etc.

The Used, Rental and eBook copies of this book are not guaranteed to include any supplemental materials. Typically, only the book itself is included. This is true even if the title states it includes any access cards, study guides, lab manuals, CDs, etc.