Design, Control, and Application of Modular Multilevel Converters for HVDC Transmission Systems

Preface xiii
 
Acknowledgements xv
 
About the Companion Website xvii
 
Nomenclature xix
 
Introduction 1
 
1 Introduction to Modular Multilevel Converters 7
 
1.1 Introduction 7
 
1.2 The Two-Level Voltage Source Converter 9
 
1.2.1 Topology and Basic Function 9
 
1.2.2 Steady-State Operation 12
 
1.3 Benefits of Multilevel Converters 15
 
1.4 Early Multilevel Converters 17
 
1.4.1 Diode Clamped Converters 17
 
1.4.2 Flying Capacitor Converters 20
 
1.5 Cascaded Multilevel Converters 23
 
1.5.1 Submodules and Submodule Strings 23
 
1.5.2 Modular Multilevel Converter with Half-Bridge Submodules 28
 
1.5.3 Other Cascaded Converter Topologies 43
 
1.6 Summary 57
 
2 Main-Circuit Design 60
 
2.1 Introduction 60
 
2.2 Properties and Design Choices of Power Semiconductor Devices for High-Power Applications 61
 
2.2.1 Historical Overview of the Development Toward Modern Power Semiconductors 61
 
2.2.2 Basic Conduction Properties of Power Semiconductor Devices 64
 
2.2.3 P-N Junctions for Blocking 65
 
2.2.4 Conduction Properties and the Need for Carrier Injection 67
 
2.2.5 Switching Properties 72
 
2.2.6 Packaging 73
 
2.2.7 Reliability of Power Semiconductor Devices 80
 
2.2.8 Silicon Carbide Power Devices 84
 
2.3 Medium-Voltage Capacitors for Submodules 92
 
2.3.1 Design and Fabrication 93
 
2.3.2 Self-Healing and Reliability 95
 
2.4 Arm Inductors 96
 
2.5 Submodule Configurations 98
 
2.5.1 Existing Half-Bridge Submodule Realizations 99
 
2.5.2 Clamped Single-Submodule 104
 
2.5.3 Clamped Double-Submodule 105
 
2.5.4 Unipolar-Voltage Full-Bridge Submodule 106
 
2.5.5 Five-Level Cross-Connected Submodule 107
 
2.5.6 Three-Level Cross-Connected Submodule 107
 
2.5.7 Double Submodule

Kamran Sharifabadi, Power Grid & Regulatory Affairs, Statoil, Norway Kamran has twenty-five years of international experience in the field of HVDC technology projects. He started out as a research engineer in ABB and Siemen, worked as a consultant for five years, then became a manager at the Norwegian TSO. He is currently a senior technology advisor for Statoil`s HVDC projects, a guest lecturer in the topics of VSC HVDC, Wind power generation technologies at NTNU and at various different universities in central Europe. Kamran is an active member of the Cigre B4 (HVDC) working group and the leader of the steering committee for a European research project on DC grids.
 
Remus Teodorescu, Aalborg University, Denmark Remus is an Associate Professor at the Institute of Technology, teaching courses in power electronics and electrical energy system control. He has authored over 80 journal and conference papers and two books. He is the founder and coordinator of the Green Power Laboratory at Aalborg University, and is co-recipient of the Technical Committee Prize Paper Award at IEEE Optim 2002.
 
Hans Peter Nee, KTH, Sweden Hans is Professor of Power Electronics in the Department of Electrical Engineering. He has supervised and examined ten finalized doctor's projects, and was awarded the Elforsk Scholarship in 1997. He has served on the board of the IEEE Sweden Section for many years and was Chairman during 2002 and 2003. He is also a member of EPE and serves in the Executive Council and in the International Steering Committee.
 
Lennart Harnefors, ABB, Västerås, Sweden Lennart is currently with ABB Power Systems - HVDC, Ludvika, Sweden as an R&D Project Manager and Principal Engineer, and with KTH as an Adjunct Professor of power electronics. Between 2001 and 2005, he was a part-time Visiting Professor of electrical drives with Chalmers University of Technology, Sweden. He is an Associate Editor of the IEEE Transactions on Industrial