Control of Power Inverters in Renewable Energy and Smart Grid Integration

by Zhong, Qing-chang; Hornik, Tomas

• ISBN13: 9780470667095
• ISBN10: 0470667095
• Edition: 1st
• Format: Hardcover
• Copyright: 2013-02-11
• Publisher: Wiley-IEEE Press

Summary

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.

Author Biography

Dr Qing-Chang Zhong, Department of Electrical Engineering and Electronics, The University of Liverpool, UK
Dr Zhong has been working in the area of control for more than 20 years, in the area of power electronics for ten and in renewable energy for five.He has made significant contributions to these areas and has established a team of ten researchers, working on power electronics and renewable energy, with funding from various sources including Rolls Royce and Texas Instruments. He has set up a well-equipped research lab, having a few inverters with different power ratings for different applications. Dr Zhong has been Senior Lecturer at the Department of Electrical Engineering and Electronics, University of Liverpool, since August 2005. He is currently a Senior Research Fellow of the Royal Academy of Engineering and Leverhulme Trust, as well as a Senior Member of IEEE, and a member of IET and UKACC.

Mr Tomas Hornik, University of Liverpool, UK
Mr Hornik is currently completeing a Ph.D. degree in Electrical Engineering at the University of Liverpool. His research interests cover power electronics, advanced control theory and DSP-based control applications. He has had more than ten years working experience in industry as a system engineer responsible for commissioning and software design in systems for power generation and distribution, control systems for central heating systems and building management systems. He is a member of the IET.

Table of Contents

Dedication xv

Preface xvii

Foreword xix

Acknowledgements xxi

About the Authors xxiii

List of Abbreviations xxvi

List of Figures xxxviii

List of Tables xl

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 43
1.5 Solar Power Systems 52
1.6 Smart Grid Integration 54

2 Preliminaries 65
2.1 Power Quality Issues 65
2.2 Repetitive Control 69
2.3 Reference Frames 72

Part One Power Quality Control 81

3 Current H∞ Repetitive Control 83
3.1 System Description 83
3.2 Controller Design 84
3.3 Design Example 88
3.4 Experimental Results 90
3.5 Summary 92

4 Voltage and Current H∞ Repetitive Control 95
4.1 System Description 95
4.2 Modelling of an Inverter 96
4.3 Controller Design 97
4.4 Design Example 102
4.5 Simulation Results 104
4.6 Summary 108

5 Voltage H∞ Repetitive Control with a Frequency-adaptiveMechanism 109
5.1 System Description 109
5.2 Controller Design 110
5.3 Design Example 116
5.4 Experimental Results 117
5.5 Summary 123

6 Cascaded Current-VoltageH∞ 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 145

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 156
7.6 Experimental Results for R-, L- and C-inverters 158
7.7 Impact of the Filter Capacitor 161
7.8 Summary 162

8 Bypass of Harmonic Current Components 163
8.1 Controller Design 163
8.2 Physical Interpretation of the Controller 165
8.3 Stability Analysis 167
8.4 Experimental Results 169
8.5 Summary 169

9 Power Quality Issues in Traction Power Systems 171
9.1 Introduction 171
9.2 Description of the Topology 174
9.3 Compensation of Negative-sequence Currents, Reactive Power and Harmonic Currents 174
9.4 Special Case: cose = 1 178
9.5 Simulation Results 180
9.6 Summary 182

Part Two Neutral Line Provision 185

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-controlledNeutral Leg 190
10.5 Summary 190

11 Classical Control of a Neutral Leg 193
11.1 Mathematical Modelling 193
11.2 Controller Design 195
11.3 Performance Evaluation 198
11.4 Selection of the Components 200
11.5 Simulation Results 201
11.6 Summary 204

12 H∞ Voltage–Current Control of a Neutral Leg 205
12.1 Mathematical Modelling 205
12.2 Controller Design 207
12.3 Selection of Weighting Functions 211
12.4 Design Example 212
12.5 Simulation Results 213
12.6 Summary 214

13 Parallel PI Voltage–H∞ Current Control of a Neutral Leg 215
13.1 Description of the Neutral Leg 215
13.2 Design of an H∞ Current Controller 217
13.3 Addition of a Voltage Control Loop 221
13.4 Experimental Results 223
13.5 Summary 226

14 Applications in Single-phase to Three-phase Conversion 229
14.1 Introduction 229
14.2 The Topology under Consideration 231
14.3 Basic Analysis 233
14.4 Controller Design 235
14.5 Simulation Results 240
14.6 Summary 242

Part Three Power Flow Control 245

15 Current Proportional–Integral Control 247
15.1 Control Structure 247
15.2 Controller Implementation 249
15.3 Experimental Results 250
15.4 Summary 254

16 Current Proportional-Resonant Control 255
16.1 Proportional-Resonant Controller 255
16.2 Control Structure 256
16.3 Controller Design 257
16.4 Experimental Results 259
16.5 Summary 262

17 Current Deadbeat Predictive Control 265
17.1 Control Structure 265
17.2 Controller Design 265
17.3 Experimental Results 267
17.4 Summary 271

18 Synchronverters: Grid-friendly Inverters that Mimic Synchronous Generators 273
18.1 Mathematical Model of Synchronous Generators 274
18.2 Implementation of a Synchronverter 277
18.3 Operation of a Synchronverter 279
18.4 Simulation Results 282
18.5 Experimental Results 285
18.6 Summary 290

19 Parallel Operation of Inverters 293
19.1 Introduction 293
19.2 Problem Description 295
19.3 Power Delivered to a Voltage Source 295
19.4 Conventional Droop Control 297
19.5 Inherent Limitations of Conventional Droop Control 299
19.6 Robust Droop Control of R-inverters 304
19.7 Robust Droop Control of C-inverters 311
19.8 Robust Droop Control of L-inverters 318
19.9 Summary 327

20 Robust Droop Control with Improved Voltage Quality 329
20.1 Control Strategy 329
20.2 Experimental Results 331
20.3 Summary 340

21 Harmonic Droop Controller to Improve Voltage Quality 341
21.1 Model of an Inverter System 341
21.2 Power Delivered to a Current Source 343
21.3 Reduction of Harmonics in the Output Voltage 344
21.4 Simulation Results 347
21.5 Experimental Results 349
21.6 Summary 351

Part Four Synchronisation 353

22 Conventional Synchronisation Techniques 355
22.1 Introduction 355
22.2 Zero-crossing Method 356
22.3 Basic Phase-Locked Loops (PLL) 357
22.4 PLL in the Synchronously Rotating Reference Frame (SRF-PLL) 358
22.5 Second-Order Generalised Integrator-based PLL (SOGI-PLL) 360
22.6 Sinusoidal Tracking Algorithm (STA) 361
22.7 Simulation Results with SOGI-PLL and STA 363
22.8 Experimental Results with SOGI-PLL and STA 365
22.9 Summary 369

23 Sinusoid-Locked Loops 373
23.1 Single-phase SynchronousMachine (SSM) Connected to the Grid 373
23.2 Structure of a Sinusoid-Locked Loop (SLL) 374
23.3 Tracking of the Frequency and the Phase 375
23.4 Tracking of the Voltage Amplitude 376
23.5 Tuning of the Parameters 376
23.6 Equivalent Structure 377
23.7 Simulation Results 379
23.8 Experimental Results 382
23.9 Summary 385

References

Bibliography 387