Preface xv 1 On the DC Microgrids Protection Challenges, Schemes, and Devices – A Review 1Mohammed H. Ibrahim, Ebrahim A. Badran and Mansour H. Abdel-Rahman 1.1 Introduction 2 1.2 Fault Characteristics and Analysis in DC Microgrid 4 1.3 DC Microgrid Protection Challenges 7 1.3.1 Low Inductance of DC System 7 1.3.2 Fast Rise Rate of DC Fault Current 7 1.3.3 Difficulties of Overcurrent (O/C) Relays Coordination 7 1.3.4 Fault Detection and Location 8 1.3.5 Arcing Fault Detection and Clearing 10 1.3.6 Short-Circuit (SC) Analysis and Change of Its Level 13 1.3.7 Non-Suitability of AC Circuit Breakers (ACCBs) 16 1.3.8 Inverters Low Fault Current Capacity 17 1.3.9 Constant Power Load (CPL) Impact 17 1.3.10 Grounding 18 1.4 DC Microgrid Protection Schemes 21 1.4.1 The Differential Protection-Based Strategies 25 1.4.2 The Voltage-Based Protection Strategies 27 1.4.3 The Adaptive Overcurrent Protection Schemes 28 1.4.4 Impedance-Based Protection Strategy (Distance Protection) 29 1.4.5 Non-Conventional Protection Schemes (Data-Based Protection Scheme) 32 1.5 DC Microgrid Protective Devices (PDs) 34 1.5.1 Z-Source DC Circuit Breakers (ZSB) 35 1.5.2 Hybrid DC Circuit Breakers (HCB) 38 1.5.3 Solid State Circuit Breakers (SSCBs) 42 1.5.4 Arc Fault Current Interrupter (AFCI) 45 1.5.5 Fuses 47 1.6 Conclusions 48 References 50 2 Control Strategies for DC Microgrids 63Bhabani Kumari Choudhury and Premalata Jena 2.1 Introduction: The Concept of Microgrids 63 2.1.1 DC Microgrids 64 2.2 Introduction: The Concept of Control Strategies 65 2.2.1 Basic Control Schemes for DC MGs 66 2.2.1.1 Centralized Control Strategy 66 2.2.1.2 Decentralized Controller 67 2.2.1.3 Distributed Control 68 2.2.2 Multilevel Control 68 2.2.2.1 Primary Control 69 2.2.2.2 Secondary Control 73 2.2.2.3 Tertiary Control 74 2.2.2.4 Current Sharing Loop 74 2.2.2.5 Microgrid Central Controller (MGCC) 74 2.3 Control Strategies for DGs in DC MGs 76 2.3.1 Control Strategy for Solar Cell in DC MGs 76 2.3.1.1 Control Strategy for Wind Energy in DC MGs 77 2.3.1.2 Control Strategy for Fuel Cell in DC MGs 77 2.3.1.3 Control Strategy for Energy Storage System in DC MGs 78 2.4 Conclusions and Future Scopes 79 References 80 3 Protection Issues in DC Microgrids 83Bhabani Kumari Choudhury and Premalata Jena 3.1 Introduction 83 3.1.1 Protection Challenge 84 3.1.1.1 Arcing and Fault Clearing Time 84 3.1.1.2 Stability 85 3.1.1.3 Multiterminal Protections 85 3.1.1.4 Ground Fault Challenges 85 3.1.1.5 Communication Challenges 86 3.1.2 Effect of Constant Power Loads (CPLs) 86 3.2 Fault Detection in DC MGs 87 3.2.1 Principles and Methods of Fault Detection 87 3.2.1.1 Voltage Magnitude-Based Detection 87 3.2.1.2 Current Magnitude-Based Detection 88 3.2.1.3 Impedance Estimation Method 88 3.2.1.4 Power Probe Unit (PPU) Method 88 3.3 Fault Location 92 3.3.1 Passive Approach 92 3.3.1.1 Traveling Wave-Based Scheme 92 3.3.1.2 Differential Fault Location 93 3.3.1.3 Local Measurement-Based Fault Location 93 3.3.2 Active Approach for Fault Location 94 3.3.2.1 Injection-Based Fault Location 94 3.4 Islanding Detection (ID) 94 3.4.1 Types of IDSs 95 3.4.2 Passive Detection Schemes (PDSs) for DC MGs 96 3.4.3 Active Detection Schemes (ADS) for DC MGs 96 3.5 Protection Coordination Strategy 97 3.6 Conclusion and Future Research Scopes 97 References 97 4 Dynamic Energy Management System of Microgrid Using AI Techniques: A Comprehensive & Comparative Study 101Priyadarshini Balasubramanyam and Vijay K. Sood Nomenclature 102 4.1 Introduction 103 4.1.1 Background and Motivation 103 4.1.2 Prior Work 103 4.1.3 Contributions 104 4.1.4 Layout of the Chapter 104 4.2 Problem Statement 104 4.3 Mathematical Modelling of Microgrid 105 4.3.1 Cost Functions 106 4.3.1.1 Diesel Generator 106 4.3.1.2 Solar Generation 106 4.3.1.3 Wind Generation Unit 106 4.3.1.4 Energy Storage System (ESS) 107 4.3.1.5 Transaction with Utility 108 4.3.2 Objective Function 109 4.3.3 Constraints 109 4.4 Optimization Algorithm 110 4.4.1 Heuristic-Based Genetic Algorithm (GA) 110 4.4.2 Pattern Search Algorithm (PSA) 111 4.5 Results 113 4.6 Conclusion 118 References 118 5 Energy Management Strategies Involving Energy Storage in DC Microgrid 121S. K. Rai, H. D. Mathur and Sanjeevikumar Padmanaban 5.1 Introduction 121 5.2 Literature Review 123 5.2.1 Classic Approaches of EMS 124 5.2.2 Meta-Heuristic Approach of EMS 129 5.2.3 Artificial Intelligence Approach of EMS 134 5.2.4 Model Predictive, Stochastic and Robust Programming Approach of EMS 139 5.3 Case Study 142 5.3.1 Energy Management System 144 5.3.2 Objective Functions 144 5.3.3 Result and Discussion 145 5.4 Conclusion 151 References 151 6 A Systematic Approach for Solar and Hydro Resource Assessment for DC Microgrid Applications 159Sanjay Kumar, Nikita Gupta, Vineet Kumar and Tarlochan Kaur 6.1 Introduction 160 6.1.1 Micro Hydro and Solar PV 162 6.1.2 Renewable Energy for Rural Electrification in Indian Perspective 162 6.1.3 Solar Resource Assessment 163 6.1.4 Hydro Resource Assessment 166 6.1.5 Demand Assessment 167 6.2 Methodology 168 6.2.1 Data Collection 168 6.2.1.1 Meteorological and Geographical Data 168 6.2.1.2 Discharge Data for Hydro Potential Estimation 168 6.3 Result and Discussion 172 6.3.1 ANN Architecture 172 6.3.2 Hydro Resource Estimation 176 6.4 Conclusion 178 References 179 7 Secondary Control Based on the Droop Technique for Power Sharing 183Waner W.A.G. Silva, Thiago R. de Oliveira, Rhonei P. Santos and Danilo I. Brandao 7.1 Introduction 184 7.2 Voltage Deviation and Power Sharing Issues in Droop Technique 186 7.2.1 Approaches for Correcting Power and Current Sharing 190 7.2.2 Hybrid Secondary Control: Distributed Power Sharing and Decentralized Voltage Restoration 197 7.2.2.1 Dynamics and Convergence of the Power Sharing Correction 200 7.2.2.2 Communication Delays in Consensus-Based Algorithm 203 7.2.2.3 Secondary Control Modeling 204 7.2.2.4 Computational and Experimental Validation 208 7.2.3 Secondary Level Control Based on Unique Voltage-Shifting (vs) 215 7.2.3.1 Power Sharing and Average Voltage Convergence Analysis 218 7.2.3.2 Secondary Control Level Modeling 223 7.2.3.3 Computational and Experimental Validation 226 7.3 Design and Implementation of the Communication System 230 7.4 Conclusions 234 References 235 8 Dynamic Analysis and Reduced-Order Modeling Techniques for Power Converters in DC Microgrid 241Divya Navamani J., Lavanya A., Jagabar Sathik, M.S. Bhaskar and Vijayakumar K. 8.1 Introduction 242 8.2 Need of Dynamic Analysis for Power Converters 243 8.3 Various Modeling Techniques 245 8.3.1 Analysis from Modeling Method 249 8.4 Reduce-Order Modeling 253 8.4.1 Faddeev Leverrier Algorithm 253 8.4.1.1 Procedure for Faddeev Leverrier Algorithm 253 8.4.1.2 Illustrative Example with Switched- Inductor-Based Quadratic Boost Converter 254 8.4.2 Order Reduction of Transfer Function 257 8.4.3 Techniques for Model Order Reduction 257 8.4.4 Pole Clustering Method 258 8.4.5 Procedure for Improved Pole Clustering Technique 258 8.4.5.1 Computation of Denominator Polynomial of Lower-Dimensional Model 259 8.4.5.2 Computation of Numerator Polynomial of Lower-Dimensional Model 261 8.4.5.3 Design of Controller 261 8.5 Illustrative Example with the Power Converter 262 8.5.1 Derivation of the Denominator 263 8.5.2 Derivation of the Numerator 264 8.6 Controllers for Power Converter 265 8.6.1 Need of Controller 265 8.6.2 Types of Controller 265 8.7 Conclusion 267 References 267 9 Matrix Converter and Its Probable Applications 273Khaliqur Rahman 9.1 Introduction 274 9.2 Classification of Matrix Converter 275 9.2.1 Classical Matrix Converter 277 9.2.2 Sparse Matrix Converter 277 9.2.3 Very Sparse Matrix Converter 277 9.2.4 Ultra-Sparse Matrix Converter 278 9.3 Problems Associated with the MC and the Drives 280 9.3.1 Commutation Issues 280 9.3.2 Modulation Issues 280 9.3.3 Common-Mode Voltage and Common-Mode Current Issues 280 9.3.4 Protection Issues 281 9.4 Control Techniques 282 9.5 Basic Components of the Matrix Converter Fed Drive System 283 9.6 Industrial Applications of Matrix Converter 289 9.7 Summary 294 References 294 10 Multilevel Converters and Applications 299P. Prem, Jagabar Sathik and K.T. Maheswari 10.1 Introduction 300 10.2 Multilevel Inverters 301 10.2.1 Multilevel Inverters vs. Two-Level Inverters 301 10.2.2 Advantages of Multilevel Converters Based on Waveforms 303 10.2.3 Advantages of Multilevel Converters Based on Topology 304 10.3 Traditional Multilevel Inverter Topologies 305 10.3.1 Diode Clamped Multilevel Inverter 305 10.3.1.1 Features of DCMLI 308 10.3.1.2 Advantages of DCMLI 308 10.3.1.3 Disadvantages of DCMLI 308 10.3.1.4 Applications of DCMLI 309 10.3.2 Flying Capacitor Multilevel Inverter 309 10.3.2.1 Features of FCMLI 312 10.3.2.2 Advantages of FCMLI 312 10.3.2.3 Disadvantages of FCMLI 312 10.3.2.4 Applications of FCMLI 313 10.3.3 Cascaded H Bridge Multilevel Inverter 313 10.3.3.1 Features of CHBMLI 315 10.3.3.2 Advantages of CHBMLI 315 10.3.3.3 Disadvantages of CHBMLI 316 10.3.3.4 Applications of CHBMLI 316 10.4 Advent of Active Neutral Point Clamped Converter 316 10.4.1 Comparison with Traditional Topologies 319 10.4.2 Advantages of ANPC MLI 320 10.4.3 Disadvantages of ANPC MLI 320 10.5 Conclusion 322 References 322 11 A Quasi Z-Source (QZS) Network-Based Quadratic Boost Converter Suitable for Photovoltaic-Based DC Microgrids 325Amir Ghorbani Esfahlan and Kazem Varesi 11.1 Introduction 326 11.2 Proposed Converter 328 11.3 Steady-State Analyses 331 11.4 Comparison with Other Structures 335 11.5 Converter Analyzes in Discontinuous Conduction Mode (DCM) 335 11.6 Simulation Results 342 11.7 Real Voltage Gain and Losses Analyzes 346 11.8 Dynamic Behavior of the Proposed Converter 352 11.9 The Maximum Power Point Tracking (MPPT) 354 11.10 Conclusions 356 11.11 Appendix 357 References 358 12 Research on Protection Strategy Utilizing Full-Scale Transient Fault Information for DC Microgrid Based on Integrated Control and Protection Platform 361Shi Bonian and Sun Gang 12.1 Introduction 362 12.2 Topological Structure and Grounding Model of Studied Microgrid 363 12.2.1 Proposed DC Distribution Network Topology 363 12.2.2 Neutral Grounding Model 366 12.2.2.1 Grounding Position Selection 366 12.2.2.2 Grounding Mode Selection 366 12.3 Fault Characteristics of DC Microgrid 367 12.3.1 DC Unipolar Fault Characteristics 368 12.3.2 DC Bipolar Fault Characteristics 370 12.4 DC Microgrid Protection Strategy 373 12.4.1 Protection Zone Division and Protection Configuration 373 12.4.1.1 Protection Zone Division 373 12.4.1.2 Protection Configuration 375 12.4.2 Integrated Control and Protection Platform 376 12.4.3 Fault Isolation and Recovery Strategy Utilizing Full-Scale Transient Fault Information 378 12.4.3.1 Unipolar Fault Isolation and Recovery of DC Line/Bus 378 12.4.3.2 Bipolar Fault Isolation and Recovery of DC Line/Bus 380 12.5 Simulation Verification 384 12.5.1 Verification under DC Unipolar Fault 386 12.5.1.1 Metal Short Circuit Fault of DC Line 386 12.5.1.2 Unipolar Fault with High Transition Resistance 386 12.5.1.3 High Resistance Unipolar Fault with Parallel Resistance Switching Strategy 386 12.5.2 Verification under DC Bipolar Fault 390 12.6 Conclusion 394 References 395 13 A Decision Tree-Based Algorithm for Fault Detection and Section Identification of DC Microgrid 397Shankarshan Prasad Tiwari and Ebha Koley Acronyms 398 Symbols 398 13.1 Introduction 398 13.2 DC Test Microgrid System 400 13.3 Overview of Decision Tree-Based Proposed Scheme 401 13.4 DC Microgrid Protection Using Decision Tree Classifier 403 13.5 Performance Evaluation 404 13.5.1 Mode Detection Module 408 13.5.2 Fault Detection/Classification 409 13.5.3 Section Identification 409 13.5.4 Comparative Analysis of the Proposed Scheme with other DC Microgrid Protection Techniques 412 13.6 Conclusion 416 References 417 14 Passive Islanding Detection Method Using Static Transfer Switch for Multi-DGs Microgrid 421Rahul S. Somalwar and S. G. Kadwane 14.1 Introduction 422 14.1.1 Technical Challenges of Microgrid and Benefits 424 14.1.2 System with Multi-DGs 425 14.1.3 Power Sharing Methods 426 14.1.3.1 Conventional Droop Control Method 426 14.2 Islanding 427 14.2.1 Challenges with Islanding 427 14.2.2 Different Standards for Microgrid 428 14.2.3 Islanding Detection Methods 428 14.3 Static Transfer Switch (STS) 431 14.3.1 Simulation Results of STS 432 14.4 Proposed Scheme of Islanding 435 14.4.1 Proposed PV System 435 14.4.2 Mathematical Analysis of Harmonic Extraction 436 14.5 Flow Chart 437 14.6 Simulation Results 438 14.7 Experimental Results 441 14.8 Conclusion 445 References 446 Index 449

Written and edited by a team of well-known and respected experts in the field, this new volume on DC microgrids presents the state-of-the-art developments and challenges in the field of microgrids for sustainability and scalability for engineers, researchers, academicians, industry professionals, consultants, and designers. The electric grid is on the threshold of a paradigm shift. In the past few years, the picture of the grid has changed dramatically due to the introduction of renewable energy sources, advancements in power electronics, digitalization, and other factors. All these megatrends are pointing toward a new electrical system based on Direct Current (DC). DC power systems have inherent advantages of no harmonics, no reactive power, high efficiency, over the conventional AC power systems. Hence, DC power systems have become an emerging and promising alternative in various emerging applications, which include distributed energy sources like wind, solar and Energy Storage System (ESS), distribution networks, smart buildings, remote telecom systems, and transport electrification like electric vehicles (EVs). All these applications are designed at different voltages to meet their specific requirements individually because of the lack of standardization. Thus, the factors influencing the DC voltages and system operation needed to be surveyed and analyzed, which include voltage standards, architecture for existing and emerging applications, topologies and control strategies of power electronic interfaces, fault diagnosis and design of the protection system, optimal economical operation, and system reliability.