Ali Keyhani and Muhammad Marwali (Eds.)

Smart Power Grids 2011

ÖSpr i nger

Contents

1 Smart Power Grids 1 Ali Keyhani 1.1 Introduction 1 1.2 Solar Energy 2 1.3 Wind Energy 3 1.4 Microgrid of Renewable and Green (MRG) Power Grids 6 1.5 Control Operation of Interconnected Network Bulk Power Grids 6 1.6 Smart Power Grid 10 1.7 Cyber Controlled Smart Power Grids 13 1.8 Research Issues 18 References 20

2 Integration of Intermittent Resource in a Real Time Scheduling 27 Muhammad Marwali 2.1 Introduction 27 2.2 Intermittent Resource Integration in Short Term Generation

Scheduling 28 2.3 Scheduling Problem Formulation 30 2.4 Proposed Method for Scheduling 33

2.4.1 Initial Feasible Solution 34 2.4.2 Thermal Unit Commitment 35 2.4.3 Dynamic Economic Dispatch 38 2.4.4 Battery Storage Model 39

2.5 Case Studies 42 List of Symbols 46 References 48

3 Load Frequency Control in a Microgrid: Challenges and Improvements 49 Ritwik Majumder, Arindam Ghosh, Gerard Ledwich 3.1 Introduction 49 3.2 Conventional Droop Control Method 50 3.3 Angle Droop Control for VSC Interfaced DGs 51

3.3.1 Angle Droop 51 3.3.2 Angle Droop Control and Power Sharing 52

Contents

3.3.3 Angle Droop and Frequency Droop Controller 52 3.3.4 Simulation Results 54

3.4 Supplementary Control Loop for Improved Power Sharing and System Stability 56 3.4.1 Test System 58 3.4.2 Simulation Studies with Supplementary Droop Controller 59

3.4.2.1 Case 1: Full System of Fig. 3.11 with Lower Droop Gains 59

3.4.2.2 Case 2: Reduced System with Lower Droop Gains 59 3.4.2.3 Case 3: System Stability with High Droop Gain 60 3.4.2.4 Case 4: Power Sharing with the Proposed

Supplementary Controller 60 3.5 Droop Control for Rural Area with High R/X Ratio 63

3.5.1 Simulation Studies 65 3.6 The Improvement in Load Sharing with Unbalanced Loads and

Application of Back To Back Converters 68 3.6.1 Power Quality Enhanced Operation of a Microgrid 68

3.6.1.1 System Structure and Reference Generation 69 3.6.1.2 Simulation Studies 70

3.6.2 Application of Back to Back Converters in Power Sharing and Power Management 75 3.6.2.1 System Structure and Operation 75

3.6.3 Back-to-Back Converter Reference Generation 76 3.6.3.1 VSC-1 Reference Generation 76 3.6.3.2 VSC-2 Reference Generation in Mode-1 77 3.6.3.3 VSC-2 Reference Generation in Mode-2 77

3.6.4 Reference Generation for DG Sources 78 3.6.5 Simulation Studies 78

3.6.5.1 Case-1: Load Sharing of the DGs with Utility 79 3.6.5.2 Case-2: Change in Power Supply from Utility 80 3.6.5.3 Case-3: Power Supply from Microgrid to Utility 80

3.7 Conclusions 81 References 81

Fuzzy Control of Multilevel Inverters for Fuel Cell Generator Sets 83

Concettina Buccella, Carlo Cecati, Antonio Piccolo, Pierluigi Siano 4.1 Introduction 83 4.2 Mathematical Model of the System and Its Fuzzy Logic Control 85 4.3 Simulation Results 90

4.3.1 General Description 90 4.3.2 Variation of the Active Power Reference 91 4.3.3 Variation of the Active Power Requested by the Load 95 4.3.4 Symmetrical Voltage Sag 97 4.3.5 Transition between the PQ Control and the PV Control 97 4.3.6 Transient Response of the Fuel Cell System 98

Contents XI

4.4 Experimental Results 98 4.4.1 Hardware Description 98

4.5 Conclusion 100 References 101

5 Control of Three-Phase Inverters in Microgrid Systems 103 Sachin Puranik, Ali Keyhani, Abir Chatterjee 5.1 Problem Statement 104 5.2 Problem Description 105

5.2.1 State Space Model of Three-Phase Inverter System 107 5.3 Control Development for Three-Phase Inverter System 116

5.3.1 Discrete-Time PID Control Design for Three-Phase Inverter 116 5.3.1.1 PID Controller Gains Tuning Steps for Three-Phase

Inverter 119 5.3.2 Discrete-Time Robust Servomechanism Problem (RSP)

Control and Discrete-Time Sliding Mode Control Design for Three-Phase Inverter 120 5.3.2.1 Design Steps for Discrete-Time RSP Control and

Discrete-Time Sliding Mode Control Design for Three-Phase Inverter 120

5.3.2.2 STEP I - Design of Discrete-Time Sliding Mode Current Control for Three-Phase Inverter 121

5.3.2.3 STEP II - Formulation of the Plant for Discrete-Time RSP Voltage Controller 124

5.3.2.4 STEP III- Design of Discrete-Time Robust Servomechanism Problem (RSP) Voltage Controller for Three-Phase Inverter 134

5.3.2.5 Necessary Conditions for the Existence of Solution of Robust Servomechanism Problem 135

5.3.2.6 Internal Model Principle 136 5.3.2.7 Design Steps for the Discrete-Time RSP Voltage

Controller for Three-Phase Inverter 138 5.3.2.8 Current Limiter for Three-Phase Inverter 155

5.4 Comparison and Tabulation of Results for the Proposed Control Techniques for Three-Phase Inverter 156

5.5 Simulation Results of Three-Phase Inverter System 158 5.6 Conclusion 174 References 175

6 Sizing High Speed Micro Generators for Smart Grid Systems 177 Adel El Shahat, Ali Keyhani 6.1 Introduction 177 6.2 Basic Selections 178

6.2.1 Permanent Magnets 178 6.2.2 Stator and Rotor Material 178

Contents

6.3 Machine Design Parameters 179 6.3.1 Stator Mechanical Design 179 6.3.2 Rotor Mechanical Design 179 6.3.3 Number of Poles and Magnets Pole Design 180 6.3.4 Magnetic Dimensions 181 6.3.5 Slots per Pole, per Phase 181 6.3.6 Stator Windings 182 6.3.7 Machine Calculated Parameters 182 6.3.8 Winding Resistances 183 6.3.9 Winding and Magnet Factors 185 6.3.10 Flux and Voltage 185 6.3.11 Machine Inductances 187 6.3.12 Basic Losses 187

6.4 Classical Sizing Results 189 6.4.1 Machine Initial Sizing 189 6.4.2 Detailed Sizing 190

6.5 Unconstrained Non-linear Optimization 194 6.5.1 Trust-Region Methods 194 6.5.2 Fminsearch Algorithm 195 6.5.3 Total Losses Minimization Sizing 196

6.6 Simple Constrained Optimization 199 6.6.1 fmincon Active Set Algorithm 199 6.6.2 Large-Scale vs. Medium-Scale Algorithms 200 6.6.3 Total Mass Minimization Sizing 201

6.7 Genetic Algorithm HSPMSG Sizing 205 6.7.1 How the Genetic Algorithm Works 205 6.7.2 Description of the Non-linear Constraint Solver 206

6.8 Efficiency Maximizer Genetic Sizing 206 6.9 Min. Mass Genetic Sizing, Constrained by Min. Losses 210 6.10 Optimum Torque per Ampere Genetic Sizing 211 6.11 Comparative Analytical Models 214

6.11.1 Rotational Stress and Retaining Sleeve 214 6.11.2 Rotor Losses 215

6.11.2.1 Model for Time Harmonics and Winding Space Harmonics 215

6.11.2.2 Model for Stator Slot Effects 218 6.11.3 Comparison Results 219

6.11.3.1 THD Comparisons 219 6.11.3.2 Parameters Comparisons 223

6.12 Conclusions 230 References 231

Control of Single-Phase DC-AC Inverters in Residential Microgrid Systems 235 Sachin Puranik, Ali Keyhani, Abir Chatterjee 7.1 Introduction 235 7.2 Model of a Single-Phase Full Bridge Inverter 237

Contents XIII

7.3 Control Development for Single-Phase Inverter System 240 7.4 Discrete-Time PID Voltage and Current Control Design 240 7.5 Discrete-Time Robust Servomechanism Problem (RSP) Control and

Discrete-Time Sliding Mode Control Design 242 7.5.1 Design Steps for Discrete-Time RSP Voltage Controller and

Discrete-Time Sliding Mode Current Controller 243 7.5.2 Step 1 - Design of Discrete-Time Sliding Mode Current

Control 243 7.5.3 Step 2 - Formulation of the Plant for Discrete-Time RSP

Voltage Controller 245 7.5.4 Step 3- Design of Discrete-Time Robust Servomechanism

Problem (RSP) Voltage Controller 248 7.6 Necessary Conditions for the Existence of Solution of Robust

Servomechanism Problem 248 7.7 Internal Model Principle 249

7.7.1 Design Steps for RSP Voltage Controller 250 7.7.2 Step (i): Servocompensator Design 250 7.7.3 Step (ii): Determination of the Augmented System 252 7.7.4 Step (iii): Design of Stabilizing Compensator 254

7.8 Simulation Results 256 7.8.1 Simulation Results with Discrete-Time PID Voltage and

Current Controllers 258 7.8.2 Simulation Results with Discrete-Time RSP Voltage

Controller and Discrete-Time Sliding Mode Current Controller 261

7.9 Conclusion 262 Acknowledgments 263 References 263

8 Intelligent Power Management of a Hybrid Fuel Cell/Energy Storage Distributed Generator 265 Amin Hajizadeh, Ali Feliachi, Masoud Aliakbar Golkar 8.1 Introduction 265 8.2 Dynamic Modeling of a Hybrid Distributed Generation (HDG)

System 266 8.2.1 Fuel Cell Model 267 8.2.2 Battery Energy Storage Model 271 8.2.3 Modeling of Grid Connected Inverter 272

8.3 Intelligent Power Management 273 8.3.1 Neuro-fuzzy Control Strategy 276

8.4 Control Design for Voltage Source Converter 278 8.5 Simulation Results 279 8.6 Summary 284 Acknowledgment 284 References 285

XIV Contents

9 Analysis and Minimization of Harmonics on the AC and DC Sides of PWM Inverters 287 PekikArgo Dahono 9.1 Introduction 287

9.1.1 Analysis and Minimization of Harmonics on the AC Side Current 288

9.2 Analysis and Minimization of Ripples on the DC Side Current and Voltage 296

9.3 Validity of the Derived Expressions 302 References 302

10 Worst Case Voltage Variation on Microgrid 305 MA. Mahmud, M.J. Hossain, H.R. Pota 10.1 Introduction 306 10.2 Voltage Variation in Conventional Distribution Network 308 10.3 Voltage Variation on Microgrid 309 10.4 Case Study: Validation of Voltage Variation Formula 311 10.5 Worst Case Voltage Variation 313 10.6 Mitigation of Voltage Variation Based on Worst Case Scenario 315

10.6.1 Mitigation of Voltage Variation by Regulating Primary DS Voltage (VS) 315

10.6.2 Mitigation of Voltage Variation by Reducing Line Resistance 316

10.6.3 Mitigation of Voltage Variation by Using Reactive Power Control 316

10.7 Voltage Level and Connection Cost 316 10.8 Conclusion 317 References 317

11 Impact of Plug-In Hybrid Electric Vehicles on Electricity Demand Profile 319

Zahra Darabi, Mehdi Ferdowsi 11.1 Introduction 319 11.2 Plug-In Hybrid Electric Vehicles 323

11.2.1 Architectures 323 11.2.2 Batteries 325

11.3 Market Penetration 326 11.4 Statistical Study of the Sides Which Form the Base of the PCLP

Prism 328 11.4.1 Vehicle Daily Mileage Analysis 328 11.4.2 Vehicles Arrival Time Analysis 331 11.4.3 Vehicles Type Analysis 331

11.5 Other Factors Associated with the PCLP Prism 332 11.5.1 Charging Infrastructure and Charging Levels 332 11.5.2 Proportional Energy Needed (PEN) ...334 11.5.3 Charging Schedule 335

XV

11.6 Developing the PCLP Curves 336 11.7 Improving Policies and Coordinated Charging 340

11.7.1 Other Charging Levels 340 11.7.2 Policy 1 341 11.7.3 Policy 2 341

11.8 Smart PHEV and Smart Grid 342 11.9 Impact on Emission 344 Summary 347 References 347

MicroGrids Operation and Control under Emergency Conditions ...351 C.L. Moreira, J.A. Pecas Lopes 12.1 Introduction 351

12.1.1 An Overview of MG Operation 352 12.2 MicroGrids Dynamic Modelling 354

12.2.1 Fuel Cells 355 12.2.1.1 Solid Oxide Fuel Cell Modelling 356

12.2.2 Microturbines 361 12.2.2.1 SSMT Active Power Control 363 12.2.2.2 SSMT Engine 364 12.2.2.3 Permanent Magnet Synchronous Generator 364 12.2.2.4 PMSG Side Converter 365

12.2.3 Micro-wind Turbines 366 12.2.4 Photovoltaic Panels 367 12.2.5 Power Electronic Interfaces Connected to the Grid 368

12.2.5.1 PQ Inverter Control 369 12.2.5.2 Voltage Source Inverter Control 371 12.2.5.3 Inverter Modelling during Short-Circuits 373

12.3 MicroGrids Emergency Control Strategies 374 12.3.1 MicroGrid Control for Islanding Operation 375

12.3.1.1 Single Master Operation 376 12.3.1.2 Multi Master Operation 377

12.3.2 Emergency Strategies 377 12.3.2.1 Frequency Control 378

12.3.3 Exploiting Low Voltage MicroGrids for Service Restoration 381 12.3.3.1 MicroGrid Black Start 383 12.3.3.2 General Requirements for MicroGrid Black

Start 384 12.3.3.3 Sequence of Actions for MicroGrid Black

Start 385 12.4 Application Example 386

12.4.1 Moving to Islanding Operation 386 12.4.2 MicroGrid Black Start 391

12.5 Final Remarks 395 References 397

XVI Contents

13 Decentralized STATCOM/ESS Control for Wind Generators 401 M.J. Hossain, H.R. Pota, M.A. Mahmud 13.1 Introduction 402 13.2 Grid-Code Requirements for Wind Farm Connections 404

13.2.1 Fault Ride-Through 405 13.2.2 Frequency-Power Variations 405 13.2.3 Frequency Control 405 13.2.4 Reactive Power Range Capability 405 13.2.5 Voltage Control 405 13.2.6 Fault Ride-Through Schemes for Wind Turbines 406

13.3 Power System Model 407 13.3.1 Modeling of Synchronous Generators 408 13.3.2 Modeling of Wind Generators 409 13.2.3 Modeling of STATCOM 410 13.3.4 Modeling of Supercapacitor 411 13.3.5 Critical Clearing Time (CCT) and Critical Voltage 412

13.4 Test System and Control Task 413 13.5 Problem Formulation 414 13.6 Decentralized Control Design Using Rank Constrained LMIs 418 13.7 Control Design Algorithm 419 13.8 Controller Performance Evaluation 421

13.8.1 Enhancement of Voltage and Transient Stability Margins ...421 13.8.2 Real and Reactive Power Output during Low Voltages 422 13.8.3 Comparisons with Standard LVRT Requirements 422 13.8.4 Performance under Different Operating Conditions 423 13.8.5 Impact of Adding Supercapacitors 423

13.9 Conclusions 423 Appendix-1 423 Appendix- II 425 Appendix-Ill 432 References 436

14 State Estimation in Smart Power Grids 439 Ali Arefi, Mahmood-Reza Haghifam 14.1 Introduction 439 14.2 The Role of State Estimation in Smart Power Grids 441 14.3 Observability Analysis 445

14.3.1 Background 445 14.3.2 The Effect of Branch Impedance Values on

Observability 446 14.3.2.1 Example 1.1: IEEE-14 Bus Test Network 449 14.3.2.1 Example 1.2: Six-Bus Network 453

14.3.3 Radial System Observability Analysis 456 14.3.3.1 Example 1.3: 17-Bus Radial Distribution

System 458

Contents XVII

14.4 Distribution State Estimation (DSE) 458 14.4.1 Conventional Weighted Least Square (WLS) 460 14.4.2 Load Correlation in a Distribution Networks 461

14.4.2.1 Load Correlation 461 14.4.2.2 The Effect of Load Correlations on DSE 463 14.4.2.3 Examplel .3: 6-Bus Radial Distribution

Feeder 463 14.5 Distribution Harmonic State Estimation (DHSE) 470 14.6 Meter Placement 471 References 471

15 Modeling, Control and Simulation of Cascaded 3-5-9 Hybrid Inverter Topology for Grid Interface Application 479 T. Wanjekeche, Dan V. Nicolae, Adisa A. Jimoh 15.1 Introduction 480 15.2 Main System Configuration 481 15.3 Principle of Operation 482

15.3.1 Phase Shifted PWM Control Technique 482 15.3.1.1 Theoretical Analysis of the Proposed PWM

Control Strategy 485 15.3.2 Development of the Switching Control Law for the

3-5-9 Hybrid Topology Model 488 15.4 Modeling and Analysis the Cascaded Hybrid Model 489

15.4.1 Average Model in ABC Co-ordinates 489 15.4.2 Development of Average Model in DQO Co-ordinates 494 15.4.3 Small Signal Analysis 497

15.5 Converter Control 498 15.5.1 Feedback Control 498 15.5.2 Balancing of the DC Capacitor Voltage 498

15.6 Simulation Analysis of a Cascaded 3-5-9 Hybrid Inverter Topology Based Grid Connected System 500 15.6.1 Simulation Results and Discussions 502

15.6.1.1 Model Response to Step Change in Load 507 15.7 Conclusion 512 References 513

16 Intelligent Multi-agent System for Smart Grid Power Management...515 Ali Feliachi, Rabie Belkacemi 16.1 Introduction 515 16.2 A Multi-agent System 516 16.3 Immune Based Multi-agent System 519 16.4 Application to Power Distribution Systems 525

16.4.1 Shipboard Power Distribution System 525 16.4.2 Analog Power Distribution System Simulator 535

16.5 Conclusion 541 Acknowledgment 541 References 542

Contents

Grid-Fault Ride-Through Control Method for a Wind Turbine Inverter 543 Ana Vladan Stankovic, Dejan Schreiber, Xiangpeng Zheng 17.1 Introduction 543 17.2 Recent Studies on Grid-Fault Ride-Through Control Methods for

Wind Turbine Inverter 544 17.3 Grid-Side Converters under Unbalanced Operating Conditions 549

17.3.1 Analysis of the Grid-Side Converter under Unbalanced Operating Conditions 550

17.4 Grid-Fault Ride-Through Generalized Control Method for a Wind Turbine Inverter 552 17.4.1 Theoretical Approach 553

17.4.1.1 Derivation 553 17.4.1.2 Critical Evaluation 556

17.4.2 Generalized Method for Grid-Fault Ride through Control for a Wind Turbine Inverter 557

17.5 Example 558 17.6 Conclusion 561 References 561

Synchronized Phasor Measurement in Smart Grid Situational Awarenes 565 Yang Jia, R. Matthew Gardner, Tao Xia, Yilu Liu 18.1 Introduction 565 18.2 Event Detection and Location 566

18.2.1 Event Trigger and Size Estimation 567 18.2.2 Event Location 570

18.3 Inter-area Oscillation Analysis 576 18.3.1 Oscillation Detection 576 18.3.2 Oscillation Mode Analysis 579

18.4 Wide-Area Frequency and Angle Visualization 582 18.4.1 Wide-Area Frequency Visualization 583 18.4.2 Wide-Area Angle Visualization 586

18.5 Summary 589 References 589

Synthesis of Droop-Based Distributed Generators in a Micro Grid System 593 Mahesh S. lllindala 19.1 Introduction 594 19.2 Droop-Based Generation Control in a Distributed Generator 595 19.3 Micro Grid System with Series Connection of Distributed

Generators 598 19.3.1 Small-Signal Dynamic Behavior 598 19.3.2 Design Guidelines 604

Contents XIX

19.4 Micro Grid System with Parallel Connection of Distributed Generators 606 19.4.1 Small-Signal Dynamic Behavior 606 19.4.2 Design Recommendations 617

19.5 Effect of Variation in Tie-Line R/X Ratio on the Dynamic Behavior of Micro Grid System 619 19.5.1 Design Recommendations 622

19.6 Summary 622 References 623

20 Modeling and Control of Fuel Cells as Distributed Generators in Smart Grids 625 Kourosh Sedghisigarchi, Ali Feliachi 20.1 Introduction 625 20.2 SOFC and РЕМ Dynamic Models 626

20.2.1 Literature Survey 626 20.2.2 РЕМ and SOFC Principles 627

20.2.2.1 РЕМ: Proton Exchange Membrane Fuel Cells 627 20.2.2.2 SOFC: Solid Oxide Fuel Cells 628

20.2.3 SOFC Dynamic Modeling 629 20.2.3.1 Component Material Balance Equations 629 20.2.3.2 Energy Balance Equations (Thermal Model) 631 20.2.3.3 Nernst's Voltage Equations 632 20.2.3.4 Developed SOFC Dynamic Model 633

20.2.4 Comparison of SOFC and РЕМ Dynamic Models 636 20.2.5 Simulation Results for a Standalone SOFC 637

20.3 Power Flow Control Strategies 639 20.3.1 Literature Survey 639 20.3.2 Active and Reactive Power Flow Control 640

20.3.2.1 Fuel Cell Control (Primary Control Loop) 641 20.3.2.2 Standalone Mode of Operation

(Secondary Control Loop) 642 20.3.2.3 Grid-Connected Mode of Operation

(Secondary Control Loop) 643 20.3.3 Simulation Results 646

20.3.3.1 Single Phase Connection 646 20.3.3.2 Three Phase Connection 647

20.4 Conclusion 650 References 651

21 Predictive Smart Grid Control with Exact Aggregated Power Constraints 655 Klaus Trangbaek, Mette Pedersen, Jan Bendtsen, Jakob Stoustrup 21.1 Introduction 655 21.2 System Description 658 21.3 Intelligent Consumers 659

XX Contents

21.4 Minkowski Addition of Resource Polytopes 660 21.5 Distribution 664

21.5.1 Mid-Ranging 666 21.6 Simulation Example 666

21.6.1 Problem Formulation 667 21.6.2 Simulation Data and Parameters 668 21.6.3 The Cautious Method 669 21.6.4 Simulation Results 669 21.6.5 Parameter Dependency 669 21.6.6 Computational Burden 672 21.6.7 Communication Load 673

21.7 Discussion 673 References 674

Author Index 675