Modular Multilevel Converters E-Book

Sixing Du

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: IEEE Press Series on Power Engineering
• Sprache: Englisch

Seitenzahl: 534

Veröffentlichungsjahr: 2018

Beschreibung

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.

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Xiaoou Li

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Jeffrey Nanzer

Zidong Wang

MODULAR MULTILEVEL CONVERTERS

Analysis, Control, and Applications

Sixing DuApparao DekkaBin WuNavid Zargari

Copyright © 2018 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, [phone], fax [phone], or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, [phone], fax [phone], or online at http://www.wiley.com/go/permission.

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Library of Congress Cataloging-in-Publication Data is available.

ISBN: 978-1-119-36630-0

To my parents Lakshmi and Pydiraju, and brother Venkatamuni

[Apparao Dekka]

and

To my parents Lingen and Peifang, and wife Janice

[Bin Wu]

CONTENTS

ABOUT THE AUTHORS

PREFACE

ORGANIZATION OF BOOK CONTENTS

SALIENT FEATURES

ACKNOWLEDGMENTS

ACRONYMS

SYMBOLS

ABOUT THE COMPANION WEBSITE

PART I GENERAL ASPECTS OF CONVENTIONAL MMC

CHAPTER 1 REVIEW OF HIGH-POWER CONVERTERS

1.1 INTRODUCTION

1.2 OVERVIEW OF HIGH-POWER CONVERTERS

1.3 VOLTAGE SOURCE CONVERTERS

1.4 CURRENT SOURCE CONVERTERS

1.5 MATRIX CONVERTERS

1.6 MODULAR MULTILEVEL CONVERTERS

1.7 SUMMARY

REFERENCES

CHAPTER 2 FUNDAMENTALS OF MODULAR MULTILEVEL CONVERTER

2.1 INTRODUCTION

2.2 MODULAR MULTILEVEL CONVERTER

2.3 PULSE WIDTH MODULATION SCHEMES

2.4 SUMMARY

REFERENCES

CHAPTER 3 CLASSICAL CONTROL OF MODULAR MULTILEVEL CONVERTER

3.1 INTRODUCTION

3.2 OVERVIEW OF CLASSICAL CONTROL METHOD

3.3 SUBMODULE CAPACITOR VOLTAGE CONTROL

3.4 OUTPUT CURRENT CONTROL

3.5 CIRCULATING CURRENT CONTROL

3.6 SUMMARY

REFERENCES

CHAPTER 4 MODEL PREDICTIVE CONTROL OF MODULAR MULTILEVEL CONVERTER

4.1 INTRODUCTION

4.2 MATHEMATICAL MODEL OF MMC

4.3 EXTRAPOLATION TECHNIQUES

4.4 COST FUNCTION AND WEIGHT FACTORS

4.5 DIRECT MODEL PREDICTIVE CONTROL

4.6 INDIRECT MODEL PREDICTIVE CONTROL

4.7 SUMMARY

REFERENCES

PART II ADVANCED MODULAR MULTILEVEL CONVERTERS

CHAPTER 5 PASSIVE CROSS-CONNECTED MODULAR MULTILEVEL CONVERTERS

5.1 INTRODUCTION

5.2 PASSIVE CROSS-CONNECTED MMC

5.3 PRINCIPLE OF OPERATION

5.4 LOW/ZERO FREQUENCY OPERATION OF PC-MMC

5.5 CLASSICAL CONTROL OF PC-MMC

5.6 SUMMARY

REFERENCES

CHAPTER 6 ACTIVE CROSS-CONNECTED MODULAR MULTILEVEL CONVERTERS

6.1 INTRODUCTION

6.2 ACTIVE CROSS-CONNECTED MMC

6.3 PRINCIPLES OF OPERATION

6.4 LOW-FREQUENCY OPERATION OF AC-MMC

6.5 CLASSICAL CONTROL OF AC-MMC

6.6 SUMMARY

REFERENCES

CHAPTER 7 STAR AND DELTA-CHANNEL MODULAR MULTILEVEL CONVERTERS

7.1 INTRODUCTION

7.2 STAR-CHANNEL MODULAR MULTILEVEL CONVERTER

7.3 PRINCIPLES OF OPERATION

7.4 LOW-FREQUENCY OPERATION OF STAR-CHANNEL MMC

7.5 CLASSICAL CONTROL OF STAR-CHANNEL MMC

7.6 DELTA-CHANNEL MODULAR MULTILEVEL CONVERTER

7.7 COMPARISON OF ADVANCED MODULAR MULTILEVEL CONVERTERS

7.8 SUMMARY

REFERENCES

PART III APPLICATIONS OF MODULAR MULTILEVEL CONVERTERS

CHAPTER 8 MODULAR MULTILEVEL CONVERTER BASED MEDIUM-VOLTAGE MOTOR DRIVES

8.1 INTRODUCTION

8.2 FUNDAMENTALS OF MMC-BASED MOTOR DRIVE

8.3 VOLTAGE-ORIENTED CONTROL OF GRID-SIDE MMC

8.4 INDIRECT FIELD-ORIENTED CONTROL OF MOTOR-SIDE MMC

8.5 LOW-SPEED OPERATION OF MMC-BASED MOTOR DRIVE

8.6 COMMON-MODE VOLTAGE ISSUES AND BLOCKING SCHEMES

8.7 TRANSFORMER-LESS MMC-BASED MOTOR DRIVE

8.8 SUMMARY

REFERENCES

CHAPTER 9 ROLE OF MODULAR MULTILEVEL CONVERTERS IN THE POWER SYSTEM

9.1 INTRODUCTION

9.2 MMC-BASED HVDC TRANSMISSION SYSTEMS

9.3 CONTROL OF TWO-TERMINAL MMC-BASED HVDC SYSTEM

9.4 CONTROL OF MULTI-TERMINAL MMC-BASED HVDC SYSTEM

9.5 MMC-BASED STATIC SYNCHRONOUS COMPENSATOR

9.6 MMC-BASED UNIFIED POWER QUALITY CONDITIONER

9.7 SUMMARY

REFERENCES

APPENDIX A MATLAB DEMO PROJECTS

INDEX

IEEE PRESS SERIES

EULA

List of Tables

Chapter 1

Table 1.1

Table 1.2

Table 1.3

Table 1.4

Table 1.5

Table 1.6

Table 1.7

Table 1.8

Table 1.9

Table 1.10

Chapter 2

Table 2.1

Table 2.2

Table 2.3

Table 2.4

Table 2.5

Table 2.6

Table 2.7

Table 2.8

Chapter 3

Table 3.1

Table 3.2

Chapter 5

Table 5.1

Chapter 6

Table 6.1

Chapter 7

Table 7.1

Table 7.2

Table 7.3

Chapter 8

Table 8.1

List of Illustrations

Chapter 1

Figure 1.1

Classification of high-power converters.

Figure 1.2

Classification of voltage source converters.

Figure 1.3

Three-level neutral-point clamped converter.

Figure 1.4

Three-level active neutral-point clamped converter.

Figure 1.5

Four-level flying capacitor converter.

Figure 1.6

Four-level nested neutral-point clamped converter.

Figure 1.7

Cascaded H-bridge converter.

Figure 1.8

Cascaded neutral-point clamped converter.

Figure 1.9

Classification of current source converter.

Figure 1.10

Load-commutated current source converter.

Figure 1.11

Pulse width modulated current source converter.

Figure 1.12

Classification of matrix power converters.

Figure 1.13

Configuration of direct matrix converter.

Figure 1.14

Configuration of indirect matrix converter.

Figure 1.15

Configuration of multi-modular matrix converter.

Figure 1.16

Configuration of 3 x 2 matrix converter.

Figure 1.17

Configuration of modular multilevel converter.

Figure 1.18

Applications of modular multilevel converter.

Figure 1.19

MMC-based motor drive with passive rectifier.

Figure 1.20

MMC-based motor drive with active rectifier.

Figure 1.21

MMC-based HVDC system.

Figure 1.22

MMC-based HVDC plus technology: (a) converter leg, (b) converter arm, and (c) submodule (Courtesy: Siemens).

Figure 1.23

Multi-terminal MMC−HVDC system.

Figure 1.24

MMC−HVDC with submarine cable for offshore wind farm.

Figure 1.25

MMC-based STATCOM system.

Figure 1.26

MMC-based UPQC system.

Chapter 3

Figure 3.1

Block diagram of MMC control system.

Figure 3.2

Block diagram of the classical control method.

Figure 3.3

Leg voltage control.

Figure 3.4

Voltage balance strategy: (a) flow chart of balancing strategy, and (b) comparison logic.

Figure 3.5

Generation of the normalized voltage waveform.

Figure 3.6

Dynamic performance of submodule capacitor voltage control approach.

Figure 3.7

Representation of three-phase variables and corresponding space phasor.

Figure 3.8

Representation of stationary-frame variables and corresponding space phasor.

Figure 3.9

Representation of

abc

and

dq

frame voltages.

Figure 3.10

MMC with the passive load.

Figure 3.11

Output current control in

dq

-frame.

Figure 3.12

Dynamic performance of output current control.

Figure 3.13

Per-phase equivalent circuit of MMC.

Figure 3.14

Circulating current control in dg-frame.

Figure 3.15

Performance of circulating current controller in

dq

-frame.

Figure 3.16

Circulating current control in

abc

-frame.

Chapter 4

Figure 4.1

Block diagram of model predictive control.

Figure 4.2

MPC schemes for MMC: (a) direct MPC, and (b) indirect MPC.

Figure 4.3

Three-phase MMC system.

Figure 4.4

Equivalent model of MMC.

Figure 4.5

Approximate discretization methods: (a) forward Euler, and (b) backward Euler.

Figure 4.6

Configuration of half-bridge submodule.

Figure 4.7

Block diagram of direct model predictive control.

Figure 4.8

Flowchart of direct model predictive control.

Figure 4.9

Dynamic performance of the direct model predictive control.

Figure 4.10

Circulating current control with DMPC.

Figure 4.11

Block diagram of an indirect model predictive control.

Figure 4.12

Flowchart of indirect model predictive control.

Chapter 5

Figure 5.1

Power circuit configuration of PC-MMC.

Figure 5.2

Configuration of converter leg in a PC-MMC.

Figure 5.3

Implementation of PSC-PWM for a PC-MMC.

Figure 5.4

Performance of the PC-MMC with a PSC-PWM.

Figure 5.5

Analysis of sub-arm and arm voltages at different modulation indices.

Figure 5.6

Equivalent circuit of a three-phase PC-MMC.

Figure 5.7

High-frequency equivalent circuit of PC-MMC.

Figure 5.8

Submodule capacitor voltage (a) without high-frequency voltage, and (b) with high-frequency voltage at low-frequency operation.

Figure 5.9

Simulated waveforms of CMV in a PC-MMC.

Figure 5.10

Block diagram of the PC-MMC control system.

Figure 5.11

Output current control in synchronous dg-frame.

Figure 5.12

Dynamic performance of output current control in the synchronous-dg frame.

Figure 5.13

Block diagram of leg capacitor voltage control.

Figure 5.14

Block diagram of arm capacitor voltage control.

Figure 5.15

Block diagram of individual SM capacitor voltage control.

Figure 5.16

Dynamic performance of SM capacitor voltage control.

Figure 5.17

Steady-state performance of the PC-MMC.

Figure 5.18

Steady-state performance of the PC-MMC.

Chapter 6

Figure 6.1

Power circuit configuration of AC-MMC.

Figure 6.2

Configuration of converter leg in an AC-MMC.

Figure 6.3

Implementation of PSC-PWM for an AC-MMC.

Figure 6.4

Implementation of PSC-PWM for an AC-MMC.

Figure 6.5

Equivalent circuit of a three-phase AC-MMC.

Figure 6.6

Submodule capacitors voltage: (a) without high-frequency voltage, and (b) with high-frequency voltage at low-frequency operation.

Figure 6.7

Simulated waveforms of CMV in an AC-MMC.

Figure 6.8

Performance comparison between square and sinusoidal high-frequency voltage in an AC-MMC.

Figure 6.9

Block diagram of the AC-MMC control system.

Figure 6.10

Block diagram of leg capacitor voltage control.

Figure 6.11

Block diagram of arm capacitor voltage control.

Figure 6.12

Block diagram of individual SM capacitor voltage control.

Figure 6.13

Dynamic performance of SM capacitor voltage control.

Figure 6.14

Steady-state performance of the AC-MMC.

Figure 6.15

Steady-state performance of the AC-MMC.

Chapter 8

Figure 8.1

MMC-based motor drive with 12 pulse passive rectifier.

Figure 8.2

MMC-based motor drive with active rectifier.

Figure 8.3

Generalized control block diagram of MMC-based motor drive.

Figure 8.4

Control block diagram of grid-side MMC.

Figure 8.5

Space phasor diagram of voltage orientation.

Figure 8.6

Implementation of PLL.

Figure 8.7

Block diagram of VOC approach.

Figure 8.8

Performance of the grid-tied MMC with VOC approach.

Figure 8.9

General control block diagram of motor-side MMC.

Figure 8.10

Space phasor diagram of field orientation.

Figure 8.11

Space vector model of induction motor in the arbitrary reference frame.

Figure 8.12

Estimation of rotor flux magnitude and position ψr and θf).

Figure 8.13

Control block diagram of IFOC.

Figure 8.14

Performance of the motor-side MMC with FOC approach.

Figure 8.15

Per-phase MMC system: (a) converter configuration and (b) equivalent model

Figure 8.16

Analysis of circuit variables in MMC.

Figure 8.17

Variation of voltage ripple with frequency.

Figure 8.18

Submodule capacitor voltage at

f

s

= 25 Hz.

Figure 8.19

Equivalent model of a three-phase MMC in low-frequency operation.

Figure 8.20

Analysis of circuit variables in MMC with high-frequency signals.

Figure 8.21

Variation of current limiting factor k

c

with frequency.

Figure 8.22

Control block diagram of motor-side MMC during low-frequency operation.

Figure 8.23

Control block diagrams: (a) CMV synthesis and (b) arm voltage control.

Figure 8.24

Performance of the motor-side MMC with high-frequency signal injection.

Figure 8.25

CMV issues in the MMC-based motor drive.

Figure 8.26

Conventional solution to block the CMV.

Figure 8.27

Parasitic capacitance of the transformer and motor in MV drive.

Figure 8.28

Transformer-less MMC-based motor drive.

Figure 8.29

Performance of the grid-side MMC in a transformer-less MV drive.

Figure 8.30

Performance of the motor-side MMC in a transformer-less drive.

Chapter 9

Figure 9.1

Applications of MMC in the power system.

Figure 9.2

Two-terminal MMC-based HVDC system.

Figure 9.3

Multi-terminal MMC-based HVDC system.

Figure 9.4

DC-side faults in the MMC-based HVDC system: (a) pole-to-pole, and (b) pole-to-ground.

Figure 9.5

Fault current path in the submodules: (a) HB-SM, (b) FB-SM, and (c) CD-SM.

Figure 9.6

Structure of a hybrid HVDC circuit breaker.

Figure 9.7

General control block diagram of the two-terminal MMC-HVDC system.

Figure 9.8

Control scheme of the sending-end converter.

Figure 9.9

Block diagram of

dq

-frame current controller.

Figure 9.10

Control scheme of the receiving-end converter.

Figure 9.11

Performance of sending-end converter station.

Figure 9.12

Performance of receiving-end converter station.

Figure 9.13

General control block diagram of multi-terminal MMC-HVDC system.

Figure 9.14

Voltage margin control of receiving-end converter.

Figure 9.15

Voltage margin control: (a)

P — V

dc

characteristics, and (b) selection of operating modes.

Figure 9.16

Performance of the three-terminal system during normal operation.

Figure 9.17

Performance of the three-terminal system during the slack bus failure.

Figure 9.18

Voltage droop control of receiving-end converter.

Figure 9.19

System configuration of MMC-based STATCOM.

Figure 9.20

Control of STATCOM under balanced grid conditions.

Figure 9.21

Performance of STATCOM under balanced grid conditions.

Figure 9.22

Control of STATCOM under unbalanced grid conditions.

Figure 9.23

Extraction of sequence components: (a) positive sequence, and (b) negative sequence.

Figure 9.24

Performance of the MMC-based STATCOM under the AC-grid fault.

Figure 9.25

System configuration of the MMC-based UPQC.

Guide

Cover

Table of Contents

Preface

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ABOUT THE AUTHORS

Sixing Dureceived his B.S. degree in electrical engineering from Taiyuan University of Science and Technology, Taiyuan, China, in 2009, and the M.S. and Ph.D. degrees in electrical engineering from Xi'an Jiaotong University, Xi'an, China, in 2011 and 2014, respectively. He is currently working as a postdoctoral research fellow at the Laboratory for Electric Drive Applications and Research (LEDAR), Ryerson University, Canada.

Dr. Du has published more than 15 journal papers in peer-reviewed Institute of Electrical and Electronics Engineers (IEEE) as the first author, and he holds 7 issued Chinese patents in the fields of power electronics, power quality, and high-voltage direct current (HVDC) transmission. His main research interests include modular multilevel converters (MMC) in power quality, HVDC transmission, and medium-voltage motor drive applications.

Dr. Du has worked closely with Rockwell Automation, Canada, and participated in NSERC/Rockwell Industrial Research Chair program and Mitacs/Rockwell Accelerate program. He has produced more than 10 technical reports on novel MMC topologies and controls. His inventions overcome the major issues of conventional MMC-based drives in zero/low-speed operation, common-mode voltage minimization, and transformer-less utilization. Some of the inventions also facilitate single-stage DC-DC conversion in MVDC/HVDC applications.

Dr. Du received national scholarship for his graduate studies (Ph.D.) from Chinese Ministry of Education in 2013, Student Research Awards from Siemens and Shindengen in 2010 and 2011, and Excellent Ph.D. Graduate Student Award from Xi'an Jiaotong University in 2014. He serves as a reviewer forIEEE Transactions on Power Electronics, IEEE Transactions on Industrial Electronics, IEEE Transactions on Industrial Informatics, IEEE Transactions on Power Delivery, IEEE Transactions on Energy Conversion, IET Power Electronics,and other international journals and conferences.

ApparaoDekkawas born in Thanam, Visakhapatnam, India. He received his B.Tec-h. degree in electrical and electronics engineering from Jawaharlal Nehru Technological University, Hyderabad, India, in 2007, an M.Tech. degree in electrical engineering with specialization in power electronics and power systems from Indian Institute of Technology Bombay, Mumbai, India, in 2010, and Ph.D. degree in electrical and computer engineering from Ryerson University, Toronto, Canada, in 2017. During 2010-2012, he worked as a research engineer at Power Electronics Laboratory, The Petroleum Institute, Abu Dhabi, UAE. He is currently working as a postdoctoral research fellow at the Laboratory for Electric Drive Applications and Research (LEDAR), Ryerson University, Canada. His research interests include high-power converters, pulse width modulation schemes, variable-speed drives, renewable energy systems, HVDC transmission systems, electric vehicles, power quality, energy storage, and model predictive control.

Dr. Dekka worked closely with Rockwell Automation, Centre for Urban Energy, Toronto Hydro, and Connect Canada, and completed several industrial projects in the field of high-power converters, power quality problems, and energy storage. He has published more than 25 peer-reviewed technical papers including 15 journal papers. He has produced more than 13 technical reports for the industry.

Dr. Dekka received national scholarship for his graduate studies (M.Tech.) from the Ministry of Human Resource Development, India, in 2008, Outstanding Reviewer Award for the year 2015 fromIEEE Transactions on Power Electronicsin 2016, Student Paper Travel Award for IEEE-ICIT16 fromIEEE Industrial Electronics Societyin 2016. During his Ph.D. studies at Ryerson University, he received Best Poster Award from the Department of Electrical and Computer Engineering in 2014, Student Research Awards from IESO, Toronto Hydro, and Connect Canada in 2013 and 2015, and the Research Excellence Award from the Department of Electrical and Computer Engineering, Ryerson University, in 2014, 2015, and 2016. He is a member of IEEE and serves as a reviewer for IEEE/IET journal and conferences.

Bin Wugraduated from Donghua University, Shanghai, China, in 1978, and received his M.A.Sc. and Ph.D. degrees in electrical and computer engineering from the University of Toronto, Canada, in 1989 and 1993, respectively. After being with Rockwell Automation, Canada, from 1992 to 1993, he joined Ryerson University, where he is currently a professor in the Department of Electrical and Computer Engineering and a Senior NSERC/Rockwell Industrial Research Chair (IRC) in Power Electronics and Electric Drives.

Dr. Wu has published more than 400 peer-reviewed technical papers and 4 Wiley-IEEE Press books, and he holds more than 30 issued and pending patents in power electronics, adjustable-speed drives, and renewable energy systems. Dr. Wu is the founder of the Laboratory for Electric Drive Applications and Research (LEDAR), which has been recognized as the most advanced research facility of its kind in a Canadian university.

Dr. Wu has worked closely with Canadian companies and assisted them in achieving technical and commercial success through research and innovation. He has authored/coauthored more than 200 technical reports. Some of his inventions and patents have been adopted by industry and implemented in the production line, resulting in significant economic benefits.

Dr. Wu received the Gold Medal of the Governor General of Canada in 1993, the Premier's Research Excellence Award in 2001, the NSERC Synergy Award for Innovation in 2002, the Ryerson Distinguished Scholar Award in 2003, the Ryerson FEAS Research Excellence Award in 2007, and the Ryerson YSGS Outstanding Contribution to Graduate Education Award and the Professional Engineers Ontario (PEO) Engineering Excellence Medal in 2014. He is a fellow of the Royal Society of Canada (RSC), Institute of Electrical and Electronics Engineers (IEEE), Engineering Institute of Canada (EIC), and Canadian Academy of Engineering (CAE). Dr. Wu is a registered professional engineer in the Province of Ontario, Canada.

NavidZargarireceived his B.Eng. degree in electrical engineering from Tehran University, Tehran, Iran, in 1987, and the M.A.Sc. and Ph.D. degrees in electrical and computer engineering from Concordia University, Montreal, Canada, in 1991 and 1995, respectively.

Dr. Zargari has been with Rockwell Automation, Canada since November 1994, first as a senior designer, then as the manager of the Medium Voltage R&D Department, and currently as a product architect. For the past 20 years, he has been involved with simulation, analysis, and design of power converters for medium voltage (MV) AC drives. His field of expertise includes converter thermal analysis, converter topologies, and semiconductor devices including SCR, IGCT, SGCT, and IGBT and their associated circuitry. As a power architect, he is a consultant to a multidisciplinary team of more than 40 electrical, mechanical, application engineers and product managers to design, develop, and bring to market medium voltage drives (2300-11,000 V, up to 10,000 HP). He creates technology road maps for the medium voltage drive and starter products, and provides technical solutions and support to the existing and potential new customers and applications. Dr. Zargari is also an adjunct professor at Ryerson University and his research interests include power converter topologies, advanced control schemes, power semiconductors, and renewable energy systems. He collaborates closely with LEDAR research team at Ryerson University in developing the leading-edge technologies for high-power MV drives. He has coauthored more than 150 research papers as well as a Wiley-IEEE Press book,Power Conversion and Control of Wind Energy Systems.He holds more than 40 US granted/pending patents in the Power Converters and Medium Voltage Applications, and received a First Prize Paper Award from theIEEE Transactions on Industry Applications.Dr. Zargari was awarded a very prestigious Premier's Catalyst Award - Innovator of the Year in 2009 with a funding of 200,000 CAD for research in wind energy technology and commercialization. Dr. Zargari is a fellow of the Institute of Electrical and Electronics Engineers (IEEE) and a registered professional engineer in the Province of Ontario, Canada.

PREFACE

The high-power multilevel converters are well known in industry and academia as the preferred choices for efficient power conversion. Over the past decade, several power converters are developed and commercialized in the form of standard and customized products that power a wide range of industrial applications. The standard power converters require either a step-up transformer or devices in series to reach the high-voltage operation. The former solution is costly and increases the size and volume of the converter system. The latter solution causes unequal voltage stress on the semiconductor devices. Currently, the modular approach is employed in the designing of the power converters for the high-voltage, high-power applications. This approach is cost-effective and uses low-voltage, low-cost semiconductor technology to build the high-power converters. There are few developments namely; cascaded H-bridge, H-bridge neutral-point clamped, and modular multilevel converter (MMC).

Among them, the MMC is one of the fast-growing technologies and received wide acceptance from both industry and academia. Modular multilevel converters feature the highest degree of modularity and the redundancy due to the large number of submodules they have, as well as the lowest harmonic content due to the large number of output voltage levels they produce. The larger number of submodules substantially increases the converter controller complexity, but each submodule offers a simple structure, reducing the manufacturing costs. Currently, the modular multilevel converters are used in applications like variable speed motor drives, grid integration of off-shore wind farms, HVDC transmission systems, railway traction power supplies, and power quality improvement. Over the past decade, a numerous books on conventional high-power converters focusing on specific areas of control, modeling and analysis, and applications have been published. However, books with a comprehensive analysis, control, and modeling of MMC technologies for a wide range of applications seems not available. This book is intended to fill this gap.

This book covers a wide range of topics from electrical engineering that involves power electronics, electrical machines, control theory, and power systems. The contents of this book include an overview of high-power converters, reference frame theory, modeling and operation of conventional and advanced modular multilevel converters, pulse width modulation schemes, classical and advanced control methods, modeling of AC drives, advanced drive control schemes, transformer-less motor drives, low/zero-speed operation, modeling and control of two-terminal and multi-terminal HVDC systems, active and reactive power control, DC-side fault protection, power quality problems, reactive power, unbalance compensation, modeling and control of static synchronous compensator (STATCOM), and unified power quality conditioner (UPQC). The book reflects the latest developments in the field, and it is a valuable reference book for academic researchers, practicing engineers, and other professionals. Also, this book can be used as a textbook for graduate-level courses.

ORGANIZATION OF BOOK CONTENTS

This book contains three parts with nine chapters. The overview and content of each chapter are described below:

Part I is composed of four chapters related to the analysis, modeling, and control of the conventional MMC. Chapter 1 provides an overview of high-power converters such as voltage source converters, current source converters, matrix converters, and modular multilevel converters, and their technical challenges and applications. Chapter 2 introduces the fundamentals of the MMC, including the submodule (SM) configurations and their operation. Also, the implementation and comprehensive analysis of pulse width modulation schemes (PWM) for an MMC are presented. Chapter 3 presents the classical control approach for the MMC, including submodule capacitor voltage, output current, and circulating current control schemes. Chapter 4 discusses the direct and indirect model predictive control (MPC) schemes for an MMC, where the important issues such as discrete-time modeling, extrapolation techniques, cost function formulation, selection of weight factors, and computational complexity are addressed.

Part II contains three chapters focused on the analysis, modeling, and control of advanced modular multilevel converters. Chapter 5 presents the circuit configuration, control and low/zero-frequency operation of the passive cross-connected modular multilevel converter (PC-MMC). Chapter 6 discusses the configuration, operation, and control of the active cross-connected modular multilevel converter (AC-MMC). Also, the comprehensive analysis of submodule capacitor voltage ripple and circulating currents are presented. Chapter 7 discusses the configuration, operation, and control of the star-channel modular multilevel converter. Also, the delta-channel modular multilevel converter is introduced in this chapter.

Part III contains two chapters focused on the applications of modular multilevel converter including the medium-voltage motor drives, HVDC transmission systems, and power quality improvement. Chapter 8 presents the system configurations, drive control schemes, low/zero-speed operation, common-mode voltage issues, and transformer-less MMC drive. Chapter 9 emphasizes the operation and control of two-terminal and multi-terminal MMC-HVDC systems, DC-side fault protection, static synchronous compensator, and unified power quality conditioner.

SALIENT FEATURES

In summary, this book is a unique and comprehensive work dealing with the technical challenges, modeling, and control aspects of the conventional and advanced modular multilevel converters in a wide range of applications including the medium-voltage motor drives, HVDC transmission systems, and power quality technologies. We developed 179 figures, 26 tables, and 37 case studies in the main body of the book to transfer our knowledge to the readers effectively. Furthermore, this book has the following features:

Reflects the latest developments in the high-power converters.

Presents the comprehensive analysis on a variety of modular multilevel converters.

Presents the detailed modeling, pulse width modulation schemes, classical and advanced control methods for various modular multilevel converters.

Discusses the technical challenges associated with the modular multilevel converters in the field of medium-voltage motor drives, HVDC transmission systems, and power quality technologies.

Discusses the important concepts with the simulations.

Serves as a valuable reference for academic researchers, practicing engineers, and other professionals.

Provides adequate technical background for graduate level teaching.

Sixing DuApparao DekkaBin WuNavid Zargari

Toronto, Canada

ACKNOWLEDGMENTS

This book has been written as a result of many years of our research on modular multilevel converters. The manuscript took almost 2 years to complete. We would like to thank our colleagues and friends who have supported and helped us in this endeavor. The references section of each chapter also acknowledges the research works of various scholars who have been passionate about this research area.

We are also very thankful to the reviewers for painstakingly reviewing our book proposal and final manuscript and providing us constructive comments to improve the quality and readability of the book. Our special thanks to the Wiley/IEEE Press editor Mary Hatcher, editorial assistant Victoria Bradshaw, and production team members Danielle Lacourciere, Vishnu Narayanan, and Anand Amarnath for their help in the preparation of this manuscript. We express our intense gratitude to our families and friends who supported and inspired us in every possible way to see the completion of this work.

Sixing DuApparao DekkaBin WuNavid Zargari

Part I of this book is developed as an outgrowth of my Ph.D. dissertation entitled “High-Power Modular Multilevel Converters: Modeling, Modulation, and Control.” I am thankful to Dr. Dewei Xu at Ryerson University, and Dr. Aleksandar Prodic at the University of Toronto for their encouragement in transforming my Ph.D. dissertation into a book. I express my sincere gratitude to my former Ph.D. dissertation supervisor, Dr. Bin Wu, for his guidance and encouragement in writing this manuscript. Also, I am thankful to Dr. Navid Zargari at Rockwell Automation, Canada for his timely feedback and suggestions on our research. This book would not have been envisaged without their help. I wish to thank Drs. Venkata Yaramasu, Marcelo Perez, and Ricardo Lizana for the collaborative works on MMCs and MPC.

ApparaoDekka

ACRONYMS

2L

Two-level (converter)

3L

Three-level (converter)

4L

Four-level (converter)

5L

Five-level (converter)

3ϕ

Three-phase (generator/grid)

AC

Alternating current

AC-MMC

Active cross-connected modular multilevel converter

ANPC

Active neutral-point clamped

ABB

ASEA brown boveri

APOD

Alternate phase-opposition-disposition

BM

Blocking mode

BTB

Back-to-back

CCV

Cycloconverter

CD

Double clamp

CEPRI

China electric power research institute

CH

Cascaded half-bridge

CHB

Cascaded H-bridge

CMV

Common-mode voltage

CNPC

Cascaded neutral-point clamped

CSC

Current source converter

CSI

Current source inverter

CSR

Current source recti

fi

er

CT

Continuous time

DC

Direct current

DFOC

Direct

fi

eld-oriented control

DMC

Direct matrix converter

DMPC

Direct model predictive control

DSP

Digital signal processor

DT

Discrete time

DTC

Direct torque control

FB

Full-bridge

FC

Flying capacitor

FPGA

Field-programmable gate array

FOC

Field-oriented control

GCT

Gate-commutated thyristor

GTO

Gate turn-off thyristor

HB

Half-bridge

HNPC

H-bridge neutral-point clamped

HV

High-voltage

HVAC

High-voltage alternating current

HVDC

High-voltage direct current

IEGT

Injection-enhanced gate transistor

IFOC

Indirect

fi

eld-oriented control

IGBT

Insulated-gate bipolar transistor

IGCT

Integrated gate-commutated thyristor

IMC

Indirect matrix converter

IMPC

Indirect model predictive control

LC

Load-commutated

LCC

Line-commutated converter

LCS

Load commutation switch

LPF

Low-pass

fi

lter

LSC

Level-shifting carrier

LV

Low-voltage

MB

Main breaker

MC

Matrix converter

MMC

Modular multilevel converter

MMMC

Multi-modular matrix converter

MPC

Model predictive control

MV

Medium-voltage

NASA

National aeronautics and space administration

NLM

Nearest level modulation

NNPC

Nested neutral-point clamped

NPC

Neutral-point clamped

PCC

Point of common coupling

PC-MMC

Passive cross-connected modular multilevel converter

PD

Phase-disposition

PF

Power factor

PI

Proportional and integral

PLL

Phase locked loop

POD

Phase-opposition-disposition

PSC

Phase-shifting carrier

PTG

Pole-to-ground

PTP

Pole-to-pole

PWM

Pulse width modulation

RES

Resonant

RMS

Root mean square

SAM

Sampled average modulation

SCIM

Squirrel cage induction motor

SCR

Silicon-controlled recti

fi

er

SGCT

Symmetric gate-commutated thyristor

SHE

Selective harmonic elimination

SM

Submodule

STATCOM

Static synchronous compensator

SVM

Space vector modulation

THD

Total harmonic distortion

UFD

Ultra-fast disconnector

UPQC

Uni

fi

ed power quality conditioner

VOC

Voltage-oriented control

VSC

Voltage source converter

VSI

Voltage source inverter

VSR

Voltage source recti

fi

er