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.

Table of Contents:
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 θ = 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