Modular Multilevel Converters

An invaluable academic reference for the area of high-power converters, covering all the latest developments in the field

High-power multilevel converters are well known in industry and academia as one of the preferred choices for efficient power conversion. Over the past decade, several power converters have been developed and commercialized in the form of standard and customized products that power a wide range of industrial applications. Currently, the modular multilevel converter is a fast-growing technology and has received wide acceptance from both industry and academia. Providing adequate technical background for graduate- and undergraduate-level teaching, this book includes a comprehensive analysis of the conventional and advanced modular multilevel converters employed in motor drives, HVDC systems, and power quality improvement.

Modular Multilevel Converters: Analysis, Control, and Applications provides an overview of high-power converters, reference frame theory, classical control methods, pulse width modulation schemes, advanced model predictive control methods, modeling of ac drives, advanced drive control schemes, modeling and control of HVDC systems, active and reactive power control, power quality problems, reactive power, harmonics and unbalance compensation, modeling and control of static synchronous compensators (STATCOM) and unified power quality compensators. Furthermore, this book:

• Explores technical challenges, modeling, and control of various modular multilevel converters in a wide range of applications such as transformer and transformerless motor drives, high voltage direct current transmission systems, and power quality improvement

• Reflects the latest developments in high-power converters in medium-voltage motor drive systems

• Offers design guidance with tables, charts graphs, and MATLAB simulations

Modular Multilevel Converters: Analysis, Control, and Applications is a valuable reference book for academic researchers, practicing engineers, and other professionals in the field of high power converters. It also serves well as a textbook for graduate-level students.

Autorentext

Sixing Du, PhD, is a Postdoctoral Fellow in the Department of Electrical and Computer Engineering at Ryerson University in Toronto, Canada.

Apparao Dekka, PhD, is a Postdoctoral Fellow in the Department of Electrical and Computer Engineering at Ryerson University in Toronto, Canada. He has made significant contributions to the control and application of the MMCs.

Bin Wu, PhD, is a Professor in the Department of Electrical and Computer Engineering at Ryerson University in Toronto, Canada. He is a co-author of several Wiley-IEEE Press books.

Navid Zargari, PhD, is a Manager & Product Architect in MV Drives R&D at Rockwell Automation,
Toronto, Canada. He is a co-author of the Wiley publication Power Conversion and Control of Wind
Energy Systems.

Inhalt

About the Authors xiii

Preface xvii

Acknowledgments xxi

Acronyms xxiii

Symbols xxvii

About the Companion Website xli

Part I General Aspects of Conventional mmc

1 Review of High-Power Converters 3

1.1 Introduction 3

1.2 Overview of High-Power Converters 4

1.3 Voltage Source Converters 6

1.3.1 Neutral-Point Clamped Converter 8

1.3.2 Active Neutral-Point Clamped Converter 10

1.3.3 Flying Capacitor Converter 11

1.3.4 Nested Neutral-Point Clamped Converter 12

1.3.5 Cascaded H-bridge Converter 13

1.3.6 Cascaded Neutral-Point Clamped Converter 15

1.4 Current Source Converters 16

1.4.1 Load-Commutated Current Source Converter 16

1.4.2 PWM Current Source Converter 18

1.5 Matrix Converters 19

1.5.1 Direct Matrix Converter 19

1.5.2 Indirect Matrix Converter 20

1.5.3 Multi-Modular Matrix Converter 21

1.6 Modular Multilevel Converters 23

1.6.1 Converter Technology 24

1.6.2 Applications 24

1.6.3 Technical Challenges 31

1.7 Summary 33

References 34

2 Fundamentals of Modular Multilevel Converter 37

2.1 Introduction 37

2.2 Modular Multilevel Converter 38

2.2.1 Converter Con guration 39

2.2.2 Con guration of Submodules 39

2.2.3 Comparison of Submodules 46

2.2.4 Principle of Operation 48

2.3 Pulse Width Modulation Schemes 49

2.3.1 Phase-Shifted Carrier Modulation 51

2.3.2 Level-Shifted Carrier Modulation 59

2.3.3 Sampled Average Modulation 60

2.3.4 Space Vector Modulation 65

2.3.5 Staircase Modulation 73

2.4 Summary 77

References 77

3 Classical Control of Modular Multilevel Converter 79

3.1 Introduction 79

3.2 Overview of Classical Control Method 80

3.3 Submodule Capacitor Voltage Control 82

3.3.1 Leg Voltage Control 82

3.3.2 Voltage Balance Strategy 83

3.4 Output Current Control 88

3.4.1 Reference Frame Theory 88

3.4.2 Control of MMC with Passive Load 92

3.5 Circulating Current Control 95

3.5.1 Mathematical Model 96

3.5.2 Control in Synchronous-dq Reference Frame 97

3.5.3 Control in Stationary-abc Reference Frame 100

3.6 Summary 101

References 101

4 Model Predictive Control of Modular Multilevel Converter 103

4.1 Introduction 103

4.2 Mathematical Model of mmc 105

4.2.1 Continuous-Time Model 105

4.2.2 Discretization Methods 108

4.2.3 Discrete-Time Model 110

4.3 Extrapolation Techniques 113

4.3.1 Vector Angle Extrapolation 113

4.3.2 Lagrange Extrapolation 113

4.4 Cost Function and Weight factors 114

4.4.1 Formulation of Cost Function 114

4.4.2 Selection of Weight Factors 116

4.5 Direct Model Predictive Control 117

4.5.1 Design Procedure 117

4.5.2 Control Algorithm 120

4.6 Indirect Model Predictive Control 124

4.6.1 Design Procedure 125

4.6.2 Control Algorithm 127

4.7 Summary 128

References 128

Part II Advanced Modular Multilevel Converters

5 Passive Cross-Connected Modular Multilevel Converters 133

5.1 Introduction 133

5.2 Passive Cross-Connected mmc 134

5.2.1 Con guration of Power Circuit 134

5.2.2 Switching States and Output Voltage 135

5.3 Principle of Operation 138

5.3.1 Modeling of PC-MMC 138

5.3.2 Phase-Shifted Carrier Modulation for PC-MMC 140

5.4 Low/Zero Frequency Operation of PC-MMC 144

5.4.1 Equivalent Circuit 145

5.4.2 Design of Cross-Connected Capacitor 146 ...