Power Electronics-Enabled Autonomous Power Systems Next Generation Smart Grids

by Zhong, Qing-chang

• ISBN13: 9781118803523
• ISBN10: 1118803523
• eBook ISBN(s): 9781118803509
• Edition: 1st
• Format: Hardcover
• Copyright: 2020-06-08
• Publisher: Wiley-IEEE Press
• More Book Details

Summary

Power systems worldwide are going through a paradigm shift from centralized generation to distributed generation. This book presents the SYNDEM (i.e., synchronized and democratized) grid architecture and its technical routes to harmonize the integration of renewable energy sources, electric vehicles, storage systems, and flexible loads, with the synchronization mechanism of synchronous machines, to enable autonomous operation of power systems, and to promote energy freedom. This is a game changer for the grid. It is the sort of breakthrough — like the touch screen in smart phones — that helps to push an industry from one era to the next, as reported by Keith Schneider, a New York Times correspondent since 1982. This book contains an introductory chapter and additional 24 chapters in five parts: Theoretical Framework, First-Generation VSM (virtual synchronous machines), Second-Generation VSM, Third-Generation VSM, and Case Studies. Most of the chapters include experimental results.

As the first book of its kind for power electronics-enabled autonomous power systems, it

• introduces a holistic architecture applicable to both large and small power systems, including aircraft power systems, ship power systems, microgrids, and supergrids
• provides latest research to address the unprecedented challenges faced by power systems and to enhance grid stability, reliability, security, resiliency, and sustainability
• demonstrates how future power systems achieve harmonious interaction, prevent local faults from cascading into wide-area blackouts, and operate autonomously with minimized cyber-attacks
• highlights the significance of the SYNDEM concept for power systems and beyond

Power Electronics-Enabled Autonomous Power Systems is an excellent book for researchers, engineers, and students involved in energy and power systems, electrical and control engineering, and power electronics. The SYNDEM theoretical framework chapter is also suitable for policy makers, legislators, entrepreneurs, commissioners of utility commissions, energy and environmental agency staff, utility personnel, investors, consultants, and attorneys.

Author Biography

QING-CHANG ZHONG, PhD, FELLOW of IEEE and IET, is the Max McGraw Endowed Chair Professor in Energy and Power Engineering and Management at Illinois Institute of Technology, Chicago, USA, and the Founder and CEO of Syndem LLC, Chicago, USA. He served(s) as a Distinguished Lecturer of IEEE Power and Energy Society, IEEE Control Systems Society, and IEEE Power Electronics Society, an Associate Editor of several leading journals in control and power engineering including IEEE Transactions on Automatic Control, IEEE Transactions on Industrial Electronics, IEEE Transactions on Power Electronics, and IEEE Transactions on Control Systems Technology, a Senior Research Fellow of Royal Academy of Engineering, U.K., the U.K. Representative to European Control Association, a Steering Committee Member of IEEE Smart Grid, and a Vice-Chair of IFAC Technical Committee on Power and Energy Systems. He delivered over 200 plenary/invited talks in over 20 countries.

Table of Contents

List of Figures xix

List of Tables xxxiii

Foreword xxxv

Preface xxxvii

Acknowledgments xxxix

About the Author xli

List of Abbreviations xliii

1 Introduction 1

1.1 Motivation and Purpose 1

1.2 Outline of the Book 3

1.3 Evolution of Power Systems 7

1.3.1 Today’s Grids 8

1.3.2 Smart Grids 8

1.3.3 Next-Generation Smart Grids 8

1.4 Summary 10

Part I Theoretical Framework 11

2 Synchronized and Democratized (SYNDEM) Smart Grid 13

2.1 The SYNDEM Concept 13

2.2 SYNDEM Rule of Law – Synchronization Mechanism of Synchronous Machines 15

2.3 SYNDEM Legal Equality – Homogenizing Heterogeneous Players as Virtual Synchronous Machines (VSM) 18

2.4 SYNDEM Grid Architecture 19

2.4.1 Architecture of Electrical Systems 19

2.4.2 Overall Architecture 22

2.4.3 Typical Scenarios 23

2.5 Potential Benefits 24

2.6 Brief Description of Technical Routes 28

2.6.1 The First-Generation (1G) VSM 28

2.6.2 The Second-Generation (2G) VSM 29

2.6.3 The Third-Generation (3G) VSM 29

2.7 Primary Frequency Response (PFR) in a SYNDEM Smart Grid 30

2.7.1 PFR from both Generators and Loads 31

2.7.2 Droop 31

2.7.3 Fast Action Without Delay 31

2.7.4 Reconfigurable Virtual Inertia 31

2.7.5 Continuous PFR 32

2.8 SYNDEM Roots 32

2.8.1 SYNDEM and Taoism 32

2.8.2 SYNDEM and Chinese History 33

2.9 Summary 34

3 Ghost Power Theory 35

3.1 Introduction 35

3.2 Ghost Operator, Ghost Signal, and Ghost System 36

3.2.1 The Ghost Operator 36

3.2.2 The Ghost Signal 37

3.2.3 The Ghost System 39

3.3 Physical Meaning of Reactive Power in Electrical Systems 41

3.4 Extension to Complete the Electrical-Mechanical Analogy 43

3.5 Generalization to Other Energy Systems 46

3.6 Summary and Discussions 47

Part II 1G VSM: Synchronverters 49

4 Synchronverter Based Generation 51

4.1 Mathematical Model of Synchronous Generatorss 51

4.1.1 The Electrical Part 51

4.1.2 The Mechanical Part 53

4.1.3 Presence of a Neutral Line 54

4.2 Implementation of a Synchronverter 55

4.2.1 The Power Part 56

4.2.2 The Electronic Part 56

4.3 Operation of a Synchronverter 57

4.3.1 Regulation of Real Power and Frequency Droop Control 57

4.3.2 Regulation of Reactive Power and Voltage Droop Control 58

4.4 Simulation Results 59

4.4.1 Under Different Grid Frequencies 60

4.4.2 Under Different Load Conditions 62

4.5 Experimental Results 62

4.5.1 Grid-connected Set Mode 63

4.5.2 Grid-connected Droop Mode 63

4.5.3 Grid-connected Parallel Operation 63

4.5.4 Seamless Transfer of the Operation Mode 64

4.6 Summary 67

5 Synchronverter Based Loads 69

5.1 Introduction 69

5.2 Modeling of a Synchronous Motor 70

5.3 Operation of a PWM Rectifier as a VSM 71

5.3.1 Controlling the Power 72

5.3.2 Controlling the DC-bus Voltage 73

5.4 Simulation Results 74

5.4.1 Controlling the Power 74

5.4.2 Controlling the DC-bus Voltage 76

5.5 Experimental Results 77

5.5.1 Controlling the Power 77

5.5.2 Controlling the DC-bus Voltage 77

5.6 Summary 79

6 Control of Permanent Magnet Synchronous Generator (PMSG) Based Wind Turbines 81

6.1 Introduction 81

6.2 PMSG Based Wind Turbines 83

6.3 Control of the Rotor-Side Converter 83

6.4 Control of the Grid-Side Converter 85

6.5 Real-time Simulation Results 86

6.5.1 Under Normal Grid Conditions 87

6.5.2 Under Grid Faults 89

6.6 Summary 90

7 Synchronverter Based AC Ward Leonard Drive Systems 91

7.1 Introduction 91

7.2 Ward Leonard Drive Systems 93

7.3 Model of a Synchronous Generator 95

7.4 Control Scheme with a Speed Sensor 96

7.4.1 Control Structure 96

7.4.2 System Analysis and Parameter Selection 97

7.5 Control Scheme without a Speed Sensor 98

7.5.1 Control Structure 98

7.5.2 System Analysis and Parameter Selection 99

7.6 Experimental Results 100

7.6.1 Case 1: With a Speed Sensor for Feedback 101

7.6.2 Case 2: Without a Speed Sensor for Feedback 104

7.7 Summary 106

8 Synchronverter without a Dedicated Synchronization Unit 107

8.1 Introduction 107

8.2 Interaction of a Synchronous Generator (SG) with an Infinite Bus 109

8.3 Controller for a Self-synchronized Synchronverter 110

8.3.1 Operation after Connection to the Grid 112

8.3.2 Synchronization before Connection to the Grid 113

8.4 Simulation Results 114

8.4.1 Normal Operation 114

8.4.2 Operation under Grid Faults 118

8.5 Experimental Results 119

8.5.1 Case 1: With the Grid Frequency Below 50 Hz 119

8.5.2 Case 2: With the Grid Frequency Above 50 Hz 123

8.6 Benefits of Removing the Synchronization Unit 123

8.7 Summary 124

9 Synchronverter Based Loads without a Dedicated Synchronisation Unit 125

9.1 Controlling the DC-bus Voltage 125

9.1.1 Self-synchronization 125

9.1.2 Normal Operation 126

9.2 Controlling the Power 127

9.3 Simulation Results 127

9.3.1 Controlling the DC-bus Voltage 128

9.3.2 Controlling the Power 130

9.4 Experimental Results 131

9.4.1 Controlling the DC-bus Voltage 132

9.4.2 Controlling the Power 132

9.5 Summary 134

10 Control of a DFIG Based Wind Turbine as a VSG (DFIG-VSG) 135

10.1 Introduction 135

10.2 DFIG Based Wind Turbines 137

10.3 Differential Gears and Ancient Chinese South-pointing Chariots 138

10.4 Analogy between a DFIG and Differential Gears 139

10.5 Control of a Grid-side Converter 140

10.5.1 DC-bus Voltage Control 141

10.5.2 Unity Power Factor Control 141

10.5.3 Self-synchronization 142

10.6 Control of the Rotor-Side Converter 142

10.6.1 Frequency Control 143

10.6.2 Voltage Control 143

10.6.3 Self-synchronization 144

10.7 Regulation of System Frequency and Voltage 145

10.8 Simulation Results 146

10.9 Experimental Results 150

10.10 Summary 153

11 Synchronverter Based Transformerless Photovoltaic Systems 155

11.1 Introduction 155

11.2 Leakage Currents and Grounding of Grid-tied Converters 156

11.2.1 Ground, Grounding, and Grounded Systems 156

11.2.2 Leakage Currents in a Grid-tied Converter 158

11.2.3 Benefits of Providing a Common AC and DC Ground 159

11.3 Operation of a Conventional Half-bridge Inverter 160

11.3.1 Reduction of Leakage Currents 161

11.3.2 Output Voltage Range 161

11.4 A Transformerless PV Inverter 161

11.4.1 Topology 161

11.4.2 Control of the Neutral Leg 161

11.4.3 Control of the Inversion Leg as a VSM 164

11.5 Real-time Simulation Results 165

11.6 Summary 167

12 Synchronverter Based STATCOM without an Dedicated Synchronization Unit 169

12.1 Introduction 169

12.2 Conventional Control of STATCOM 170

12.2.1 Operational Principles 171

12.2.2 Typical Control Strategy 172

12.3 Synchronverter Based Control 173

12.3.1 Regulation of the DC-bus Voltage and Synchronization with the Grid 173

12.3.2 Operation in the Q-mode to Regulate the Reactive Power 175

12.3.3 Operation in the V-mode to Regulate the PCC Voltage 176

12.3.4 Operation in the V_D-mode to Droop the Voltage 176

12.4 Simulation Results 177

12.4.1 System Description 177

12.4.2 Connection to the Grid 179

12.4.3 Normal Operation in Different Modes 180

12.4.4 Operation under Extreme Conditions 181

12.5 Summary 185

13 Synchronverters with Bounded Frequency and Voltage 187

13.1 Introduction 187

13.2 Model of the Original Synchronverter 188

13.3 Achieving Bounded Frequency and Voltage 189

13.3.1 Control Design 190

13.3.2 Existence of a Unique Equilibrium 193

13.3.3 Convergence to the Equilibrium 197

13.4 Real-time Simulation Results 199

13.5 Summary 202

14 Virtual Inertia, Virtual Damping, and Fault Ride-through 203

14.1 Introduction 203

14.2 Inertia, the Inertia Time Constant, and the Inertia Constant 204

14.3 Limitation of the Inertia of a Synchronverter 206

14.4 Reconfiguration of the Inertia Time Constant 210

14.4.1 Design and Outcome 210

14.4.2 What is the Catch? 211

14.5 Reconfiguration of the Virtual Damping 212

14.5.1 Through Impedance Scaling with an Inner-loop Voltage Controller 213

14.5.2 Through Impedance Insertion with an Inner-loop Current Controller 214

14.6 Fault Ride-through 214

14.6.1 Analysis 214

14.6.2 Recommended Design 215

14.7 Simulation Results 215

14.7.1 A Single VSM 216

14.7.2 Two VSMs in Parallel Operation 217

14.8 Experimental Results 221

14.8.1 A Single VSM 221

14.8.2 Two VSMs in Parallel Operation 222

14.9 Summary 225

Part III 2G VSM: Robust Droop Controller 227

15 Synchronization Mechanism of Droop Control 229

15.1 Brief Review of Phase-Locked Loops (PLLs) 229

15.1.1 Basic PLL 229

15.1.2 Enhanced PLL (EPLL) 230

15.2 Brief Review of Droop Control 232

15.3 Structural Resemblance between Droop Control and PLL 234

15.3.1 When the Impedance is Inductive 234

15.3.2 When the Impedance is Resistive 236

15.4 Operation of a Droop Controller as a Synchronization Unit 238

15.5 Experimental Results 239

15.5.1 Synchronization with the Grid 239

15.5.2 Connection to the Grid 240

15.5.3 Operation in the Droop Mode 241

15.5.4 Robustness of Synchronization 241

15.5.5 Change in the Operation Mode 242

15.6 Summary 243

16 Robust Droop Control 245

16.1 Control of Inverter Output Impedance 245

16.1.1 Inverters with Inductive Output Impedances (L-inverters) 245

16.1.2 Inverters with Resistive Output Impedances (R-inverters) 246

16.1.3 Inverters with Capacitive Output Impedances (C-inverters) 247

16.2 Inherent Limitations of Conventional Droop Control 248

16.2.1 Basic Principle 248

16.2.2 Experimental Phenomena 250

16.2.3 Real Power Sharing 251

16.2.4 Reactive Power Sharing 252

16.3 Robust Droop Control of R-inverters 252

16.3.1 Control Strategy 252

16.3.2 Error due to Inaccurate Voltage Measurements 253

16.3.3 Voltage Regulation 254

16.3.4 Error due to the Global Settings for E^∗ and 𝜔^∗ 254

16.3.5 Experimental Results 255

16.4 Robust Droop Control of C-inverters 261

16.4.1 Control Strategy 261

16.4.2 Experimental Results 262

16.5 Robust Droop Control of L-inverters 262

16.5.1 Control Strategy 262

16.5.2 Experimental Results 265

16.6 Summary 268

17 Universal Droop Control 269

17.1 Introduction 269

17.2 Further Insights into Droop Control 270

17.2.1 Parallel Operation of Inverters with the Same Type of Impedance 271

17.2.2 Parallel Operation of L-, R-, and R_L-inverters 272

17.2.3 Parallel Operation of R_C-, R-, and C-inverters 273

17.3 Universal Droop Controller 275

17.3.1 Basic Principle 275

17.3.2 Implementation 276

17.4 Real-time Simulation Results 277

17.5 Experimental Results 277

17.5.1 Case I: Parallel Operation of L- and C-inverters 277

17.5.2 Case II: Parallel Operation of L-, C-, and R-inverters 279

17.6 Summary 281

18 Self-synchronized Universal Droop Controller 283

18.1 Description of the Controller 283

18.2 Operation of the Controller 285

18.2.1 Self-synchronization Mode 285

18.2.2 Set Mode (P-mode and Q-mode) 286

18.2.3 Droop Mode (P_D-mode and Q_D-mode) 286

18.3 Experimental Results 287

18.3.1 R-inverter with Self-synchronized Universal Droop Control 288

18.3.2 L-inverter with Self-synchronized Universal Droop Control 290

18.3.3 L-inverter with Self-synchronized Robust Droop Control 294

18.4 Real-time Simulation Results from a Microgrid 297

18.5 Summary 300

19 Droop-Controlled Loads for Continuous Demand Response 301

19.1 Introduction 301

19.2 Control Framework with a Three-port Converter 302

19.2.1 Generation of the Real Power Reference 302

19.2.2 Regulation of the Power Drawn from the Grid 304

19.2.3 Analysis of the Operation Modes 305

19.2.4 Determination of the Capacitance for Grid Support 306

19.3 An Illustrative Implementation with the 𝜃-converter 308

19.3.1 Brief Description about the 𝜃-converter 309

19.3.2 Control of the Neutral Leg 310

19.3.3 Control of the Conversion Leg 311

19.4 Experimental Results 311

19.4.1 Design of the Experimental System 311

19.4.2 Steady-state Performance 312

19.4.3 Transient Performance 315

19.4.4 Capacity Potential 317

19.4.5 Comparative Study 318

19.5 Summary 319

20 Current-limiting Universal Droop Controller 321

20.1 Introduction 321

20.2 System Modeling 322

20.3 Control Design 323

20.3.1 Structure 323

20.3.2 Implementation 323

20.4 System Analysis 326

20.4.1 Current-limiting Property 326

20.4.2 Closed-loop Stability 327

20.4.3 Selection of Control Parameters 328

20.5 Practical Implementation 329

20.6 Operation under Grid Variations and Faults 330

20.7 Experimental Results 331

20.7.1 Operation under Normal Conditions 332

20.7.2 Operation under Grid Faults 334

20.8 Summary 338

Part IV 3G VSM: Cybersync Machines 339

21 Cybersync Machines 341

21.1 Introduction 341

21.2 Passivity and Port-Hamiltonian Systems 343

21.2.1 Passive Systems 343

21.2.2 Port-Hamiltonian Systems 343

21.2.3 Passivity of Interconnected Passive Systems 345

21.3 System Modeling 346

21.4 Control Framework 348

21.4.1 The Engendering Block Σ_e 349

21.4.2 Generation of the Desired Frequency 𝜔_d and Flux 𝜑_d 350

21.4.3 Design of Σ_𝜔 and Σ_𝜑 to Obtain a Passive Σ_C 351

21.5 Passivity of the Controller 352

21.5.1 Losslessness of the Interconnection Block Σ_I 352

21.5.2 Passivity of the Cascade of Σ_C and Σ_I 354

21.6 Passivity of the Closed-loop System 355

21.7 Sample Implementations for Blocks Σ_𝜔 and Σ_𝜑 355

21.7.1 Using the Standard Integral Controller (IC) 355

21.7.2 Using a Static Controller 356

21.8 Self-Synchronization and Power Regulation 357

21.9 Simulation Results 358

21.9.1 Self-synchronization 360

21.9.2 Operation after Connection to the Grid 360

21.10 Experimental Results 362

21.10.1 Self-synchronization 362

21.10.2 Operation after Connection to the Grid 363

21.11 Summary 364

Part V Case Studies 365

22 A Single-node System 367

22.1 SYNDEM Smart Grid Research and Educational Kit 367

22.1.1 Overview 367

22.1.2 Hardware Structure 368

22.1.3 Sample Conversion Topologies Attainable 369

22.2 Details of the Single-Node SYNDEM System 375

22.2.1 Description of the System 375

22.2.2 Experimental Results 377

22.3 Summary 378

23 A 100% Power Electronics Based SYNDEM Smart Grid Testbed 379

23.1 Description of the Testbed 379

23.1.1 Overall Structure 379

23.1.2 VSM Topologies Adopted 379

23.1.3 Individual Nodes 382

23.2 Experimental Results 384

23.2.1 Operation of Energy Bridges 384

23.2.2 Operation of Solar Power Nodes 384

23.2.3 Operation of Wind Power Nodes 386

23.2.4 Operation of the DC-Load Node 388

23.2.5 Operation of the AC-Load Node 389

23.2.6 Operation of the Whole Testbed 391

23.3 Summary 393

24 A Home Grid 395

24.1 Description of the Home Grid 395

24.2 Results from Field Operations 396

24.2.1 Black start and Grid forming 396

24.2.2 From Islanded to Grid-tied Operation 399

24.2.3 Seamless Mode Change when the Public Grid is Lost and Recovered 400

24.2.4 Voltage/Frequency Regulation and Power Sharing 400

24.3 Unexpected Problems Emerged During the Field Trial 402

24.4 Summary 404

25 Texas Panhandle Wind Power System 405

25.1 Geographical Description 405

25.2 System Structure 406

25.3 Main Challenges 407

25.4 Overview of Control Strategies Compared 407

25.4.1 VSM Control 408

25.4.2 DQ Control 410

25.5 Simulation Results 411

25.5.1 VSM Control 412

25.5.2 DQ Control 415

25.6 Summary and Conclusions 416

Bibliography 417

Index 441