Qing-Chang Zhong received his Diploma in electrical engineering from Hunan Institute of Engineering, Xiangtan, China, in 1990, his MSc degree in electrical engineering from Hunan University, Changsha, China, in 1997, his PhD degree in control theory and engineering from Shanghai Jiao Tong University, Shanghai, China, in 1999, and his PhD degree in control and power engineering (awarded the Best Doctoral Thesis Prize) from Imperial College London, London, UK, in 2004, respectively.

He holds the Chair Professor in Control and Systems Engineering at the Department of Automatic Control and Systems Engineering, The University of Sheffield, UK. He has worked at Hunan Institute of Engineering, Xiangtan, China; Technion]CIsrael Institute of Technology, Haifa, Israel; Imperial College London, London, UK; University of Glamorgan, Cardiff, UK; The University of Liverpool, Liverpool, UK; and Loughborough University, Leicestershire, UK. He has been on sabbatical at the Cymer Center for Control Systems and Dynamics (CCSD), University of California, San Diego, USA; and the Center for Power Electronics Systems (CPES), Virginia Tech, Blacksburg, USA. He is the author or co-author of Robust Control of Time-Delay Systems (Springer-Verlag, 2006), Control of Integral Processes with Dead Time (Springer-Verlag, 2010) and Control of Power Inverters in Renewable Energy and Smart Grid Integration (Wiley-IEEE Press, 2013). His research focuses on advanced control theory and applications, including power electronics, renewable energy and smart grid integration, electric drives and electric vehicles, robust and H-infinity control, time-delay systems and process control.

He is a Specialist recognised by the State Grid Corporation of China (SGCC), a Fellow of the Institution of Engineering and Technology (IET), a Senior Member of IEEE, the Vice-Chair of IFAC TC 6.3 (Power and Energy Systems) responsible for the Working Group on Power Electronics and was a Senior Research Fellow of the Royal Academy of Engineering/Leverhulme Trust, UK (2009]C2010). He serves as an Associate Editor for IEEE Transactions on Power Electronics and the Conference Editorial Board of the IEEE Control Systems Society.

Tomas Hornik received a Diploma in Electrical Engineering in 1991 from the Technical CollegeVUzlabine, Prague, the BEng and PhD degree in electrical engineering and electronics from The University of Liverpool, UK, in 2007 and 2010, respectively. He was a postdoctoral researcher at the same university from 2010 to 2011. He joined Turbo Power Systems as a Control Engineer in 2011. His research interests cover power electronics, advanced control theory and DSP-based control applications. He had more than ten years working experience in industry as a system engineer responsible for commissioning and software design in power generation and distribution, control systems for central heating and building management. He is a member of the IEEE and the IET.

Integrating renewable energy and other distributed energy sources into smart grids, often via power inverters, is arguably the largest "new frontier" for smart grid advancements. Inverters should be controlled properly so that their integration does not jeopardize the stability and performance of power systems and a solid technical backbone is formed to facilitate other functions and services of smart grids.
This unique reference offers systematic treatment of important control problems in power inverters, and different general converter theories. Starting at a basic level, it presents conventional power conversion methodologies and then 'non-conventional' methods, with a highly accessible summary of the latest developments in power inverters as well as insight into the grid connection of renewable power.
Consisting of four parts - Power Quality Control, Neutral Line Provision, Power Flow Control, and Synchronisation - this book fully demonstrates the integration of control and power electronics.
Key features include:
* the fundamentals of power processing and hardware design
* innovative control strategies to systematically treat the control of power inverters
* extensive experimental results for most of the control strategies presented
* the pioneering work on "synchronverters" which has gained IET Highly Commended Innovation Award
Engineers working on inverter design and those at power system utilities can learn how advanced control strategies could improve system performance and work in practice. The book is a useful reference for researchers who are interested in the area of control engineering, power electronics, renewable energy and distributed generation, smart grids, flexible AC transmission systems, and power systems for more-electric aircraft and all-electric ships. This is also a handy text for graduate students and university professors in the areas of electrical power engineering, advanced control engineering, power electronics, renewable energy and smart grid integration.

Preface xvii

Acknowledgments xix

About the Authors xxi

List of Abbreviations xxiii

1 Introduction 1

1.1 Outline of the Book 1

1.2 Basics of Power Processing 4

1.3 Hardware Issues 24

1.4 Wind Power Systems 44

1.5 Solar Power Systems 53

1.6 Smart Grid Integration 55

2 Preliminaries 63

2.1 Power Quality Issues 63

2.2 Repetitive Control 67

2.3 Reference Frames 71

PART I POWER QUALITY CONTROL

3 Current H¿ Repetitive Control 81

3.1 System Description 81

3.2 Controller Design 82

3.3 Design Example 87

3.4 Experimental Results 88

3.5 Summary 91

4 Voltage and Current H¿ Repetitive Control 93

4.1 System Description 93

4.2 Modelling of an Inverter 94

4.3 Controller Design 96

4.4 Design Example 100

4.5 Simulation Results 102

4.6 Summary 107

5 Voltage H¿ Repetitive Control with a Frequency-adaptive Mechanism 109

5.1 System Description 109

5.2 Controller Design 110

5.3 Design Example 116

5.4 Experimental Results 117

5.5 Summary 126

6 Cascaded Current-Voltage H¿ Repetitive Control 127

6.1 Operation Modes in Microgrids 127

6.2 Control Scheme 129

6.3 Design of the Voltage Controller 131

6.4 Design of the Current Controller 133

6.5 Design Example 134

6.6 Experimental Results 136

6.7 Summary 147

7 Control of Inverter Output Impedance 149

7.1 Inverters with Inductive Output Impedances (L-inverters) 149

7.2 Inverters with Resistive Output Impedances (R-inverters) 150

7.3 Inverters with Capacitive Output Impedances (C-inverters) 152

7.4 Design of C-inverters to Improve the Voltage THD 153

7.5 Simulation Results for R-, L- and C-inverters 157

7.6 Experimental Results for R-, L- and C-inverters 159

7.7 Impact of the Filter Capacitor 162

7.8 Summary 163

8 Bypassing Harmonic Current Components 165

8.1 Controller Design 165

8.2 Physical Interpretation of the Controller 167

8.3 Stability Analysis 169

8.4 Experimental Results 171

8.5 Summary 172

9 Power Quality Issues in Traction Power Systems 173

9.1 Introduction 173

9.2 Description of the Topology 175

9.3 Compensation of Negative-sequence Currents, Reactive Power and Harmonic Currents 175

9.4 Special Case: cos ¿ = 1 180

9.5 Simulation Results 181

9.6 Summary 184

PART II NEUTRAL LINE PROVISION

10 Topology of a Neutral Leg 187

10.1 Introduction 187

10.2 Split DC Link 188

10.3 Conventional Neutral Leg 189

10.4 Independently-controlled Neutral Leg 190

10.5 Summary 191

11 Classical Control of a Neutral Leg 193

11.1 Mathematical Modelling 193

11.2 Controller Design 195

11.3 Performance Evaluation 199

11.4 Selection of the Components 201

11.5 Simulation Results 202

11.6 Summary 205

12 H¿ Voltage-Current Control of a Neutral Leg 207

12.1 Mathematical Modelling 207

12.2 Controller Design 210

12.3 Selection of Weighting Functions 214

12.4 Design Example 215

12.5 Simulation Results 216

12.6 Summary 217

13 Parallel PI Voltage-H¿ Current Control of a Neutral Leg 219

13.1 Description of the Neutral Leg 219

13.2 Design of an

13.3 Addition of a Voltage Control Loop 226

13.4 Experimental Results 226

13.5 Summary 230

14 Applications in Single-phase to Three-phase Conversion 233

14.1 Introduction 233

14.2 The Topology under Consideration 236

14.3 Basic Analysis 237

14.4 Controller Design 239

14.5 Simulation Results 244

14.6 Summary 248

PART III POWER FLOW CONTROL

15 Current Proportional-Integral Control 251

15.1 Control Structure 251

15.2 Controller Implementation 254

15.3 Experimental Results 254

15.4 Summary 258

16 Current Proportional-Resonant Control 259

16.1 Proportional-resonant Controller 259

16.2 Control Structure 260

16.3 Controller Design 261

16.4 Experimental Results 263

16.5 Summary 268

17 Current Deadbeat Predictive Control 269

17.1 Control Structure 269

17.2 Controller Design 269

17.3 Experimental Results 271

17.4 Summary 275

18 Synchronverters: Grid-friendly Inverters that Mimic Synchronous Generators 277

18.1 Mathematical Model of Synchronous Generators 278

18.2 Implementation of a Synchronverter 282

18.3 Operation of a Synchronverter 284

18.4 Simulation Results 287

18.5 Experimental Results 290

18.6 Summary 296

19 Parallel Operation of Inverters 297

19.1 Introduction 297

19.2 Problem Description 299

19.3 Power Delivered to a Voltage Source 300

19.4 Conventional Droop Control 301

19.5 Inherent Limitations of Conventional Droop Control 304

19.6 Robust Droop Control of R-inverters 309

19.7 Robust Droop Control of C-inverters 319

19.8 Robust Droop Control of L-inverters 326

19.9 Summary 330

20 Robust Droop Control with Improved Voltage Quality 335

20.1 Control Strategy 335

20.2 Experimental Results 337

20.3 Summary 346

21 Harmonic Droop Controller to Improve Voltage Quality 347

21.1 Model of an Inverter System 347

21.2 Power Delivered to a Current Source 349

21.3 Reduction of Harmonics in the Output Voltage 351

21.4 Simulation Results 353

21.5 Experimental Results 355

21.6 Summary 358

PART IV SYNCHRONISATION

22 Conventional Synchronisation Techniques 361

22.1 Introduction 361

22.2 Zero-crossing Method 362

22.3 Basic Phase-locked Loops (PLL) 363

22.4 PLL in the Synchronously Rotating Reference Frame (SRF-PLL) 364

22.5 Second-order Generalised Integrator-based PLL (SOGI-PLL) 366

22.6 Sinusoidal Tracking Algorithm (STA) 368

22.7 Simulation Results with SOGI-PLL and STA 369

22.8 Experimental Results with SOGI-PLL and STA 372

22.9 Summary 378

23 Sinusoid-locked Loops 379

23.1 Single-phase Synchronous Machine (SSM) Connected to the Grid 379

23.2 Structure of a Sinusoid-locked Loop (SLL) 380

23.3 Tracking of the Frequency and the Phase 382

23.4 Tracking of the Voltage Amplitude 382

23.5 Tuning of the Parameters 382

23.6 Equivalent Structure 383

23.7 Simulation Results 384

23.8 Experimental Results 386

23.9 Summary 390

References 393

Index 407