Modular Multilevel Converters: Control, Fault Detection, and Protection (IEEE

* Item Description

1 Modular Multilevel Converter 1 1.1 Introduction 1 1.2 MMC Configuration 2 1.2.1 Converter Configuration 2 1.2.2 Submodule Configuration 3 1.3 Operation Principles 3 1.3.1 Submodule Normal Operation 3 1.3.2 Submodule Blocking Operation 5 1.3.3 Converter Operation 6 1.4 Modulation Scheme 8 1.4.1 Phase-Disposition PWM 9 1.4.2 Phase-Shifted PWM 10 1.4.3 Nearest Level Modulation 12 1.5 Mathematical Model 13 1.5.1 Submodule Mathematical Model 13 1.5.1 Arm Mathematical Model 14 1.5.3 Three-Phase MMC Mathematical Model 16 1.6 Design Constraints 19 1.6.1 Power Device Design 19 1.6.2 Capacitor Design 21 1.6.3 Arm Inductor Design 23 1.7 Faults Overviews of MMCs 24 1.7.1 Internal Faults of MMCs 25 1.7.2 External Faults of MMCs 26 1.7 Summary 26 References 27 2 Control of Modular Multilevel Converter 30 2.1 Introduction 30 2.2 Overall Control of MMCs 31 2.3 Output Control of MMCs 32 2.3.1 Current Control 32 2.3.2 DC-Link Voltage and Power Control 35 2.3.3 Grid Forming Control 37 2.4 Centralized Capacitor Voltage Balancing Control 39 2.4.1 On-State SMs Number based VBC 39 2.4.2 Balancing Adjusting Number based VBC 40 2.4.3 IPS-PWM Harmonic Current based VBC 42 2.4.4 SHE-PWM Pulse Energy Sorting based VBC 51 2.4.5 PSC-PWM Pulse Energy Sorting based VBC 61 2.5 Individual Capacitor Voltage Balancing Control 73 2.5.1 Average and Balancing Control based VBC 73 2.5.2 Reference Modulation Index based VBC 75 2.5.3 Reference Phase Angle based VBC 79 2.6 Circulating Current Control 87 2.6.1 Proportional Integration Control 88 2.6.2 Multiple Proportional Resonant Control 90 2.6.3 Repetitive Control 91 2.7 Summary 92 References 93 3 Fault Detection of MMCs under IGBT Faults 96 3.1 Introduction 96 3.2 IGBT Faults 97 3.2.1 IGBT Short-Circuit Fault 98 3.2.2 IGBT Open-Circuit Fault 98 3.3 Protection and Detection under IGBT Short-Circuit Faults 99 3.3.1 SM under IGBT Short-Circuit Fault 99 3.3.3 Protection and Detection under IGBT Short-Circuit Fault 100 3.4 MMC Features under IGBT Open-Circuit Faults 102 3.4.1 Faulty SM Features under T1 Open-Circuit Fault 102 3.4.2 Faulty SM Features under T2 Open-Circuit Fault 103 3.5 Kalman Filter based Fault Detection under IGBT Open-Circuit Faults 110 3.5.1 Kalman Filter Algorithm 110 3.5.2 Circulating Current Estimation 111 3.5.3 Faulty Phase Detection 112 3.5.4 Capacitor Voltage 113 3.5.5 Faulty SM Detection 114 3.6 Integrator based Fault Detection under IGBT Open-Circuit Faults 119 3.7 STW based Fault Detection under IGBT Open-Circuit Faults 123 3.7.1 MMC Data 124 3.7.2 Sliding-Time Windows 125 3.7.3 Feature of STW 127 3.7.4 Features Relationships Between Neighboring STW 128 3.7.5 Features Extraction Algorithm 128 3.7.6 Energy Entropy Matrix 129 3.7.7 2D-CNN 130 3.7.8 Fault Detection Method 131 3.7.9 Selection of Sliding Interval 132 3.7.10 Analysis of Fault Localiztion Time 133 3.8 IF based Fault Detection under IGBT Open-Circuit Faults 140 3.8.1 IT for MMCs 141 3.8.2 SM Depth of IT 142 3.8.3 IF for MMCs 142 3.8.4 SM Average Depth in IF 143 3.8.5 IF Output 144 3.8.6 Fault Detection 144 3.8.7 Selection of mp 145 3.8.8 Selection of k 146 3.9 Summary 150 References 150 4 Condition Monitoring and Control of MMCs under Capacitor Faults 153 4.1 Introduction 153 4.2 Capacitor Equivalent Circuit in MMCs 154 4.3 Capacitor Parameter Characteristics in MMCs 156 4.3.1 Capacitor Current Characteristics 156 4.3.2 Capacitor Impedance Characteristics 158 4.3.3 Capacitor Voltage Characteristics 159 4.4 Capacitor Aging 161 4.5 Capacitance Monitoring 162 4.5.1 Capacitor Voltage and Current based Monitoring Strategy 162 4.5.2 Arm Average Capacitance based Monitoring Strategy 163 4.5.3 Reference SM based Monitoring Strategy 169 4.5.4 Sorting-based Monitoring Strategy 179 4.5.5 Temperature Effect of Capacitance 184 4.6 ESR Monitoring 185 4.6.1 Direct ESR Monitoring Strategy 185 4.6.2 Sorting-based ESR Monitoring Strategy 185 4.6.3 Temperature Effect of ESR 191 4.7 Capacitor Lifetime Monitoring 192 4.8 Arm Current Optimal Control under Capacitor Parameters Faults 193 4.8.1 Equivalent Circuit of MMCs 193 4.8.2 Arm Current Characteristics 194 4.8.3 Arm Current Optimal Control 195 4.9 SM Power Losses Optimal Control under Capacitor Aging 199 4.9.1 Equivalent SM Reference 199 4.9.2 SM Conduction Losses 201 4.9.3 SM Switching Losses 203 4.9.4 SM Power Losses Optimal Control 205 4.10 Summary 211 References 212 5 Fault Tolerant Control of MMCs under SM Faults 214 5.1 Introduction 214 5.2 SM Protection Circuit 215 5.3 Redundant Submodules 215 5.4 Fault Tolerant Scheme 217 5.4.1 Cold Reserve Mode 217 5.4.2 Spinning Reserve Mode- I 218 5.4.3 Spinning Reserve Mode- II 220 5.4.4 Spinning Reserve Mode- III 220 5.4.5 Comparison of Fault Tolerant Schemes 220 5.5 Fundamental Circulating Current Elimination based Tolerant Control 221 5.5.1 Equivalent Circuit of MMCs 221 5.5.2 Fundamental Circulating Current 223 5.5.3 Fundamental Circulating Current Elimination Control 224 5.5.4 Control Analysis 226 5.6 Summary 231 References 231 6 Control of MMCs under AC Grid Faults 233 6.1 Introduction 233 6.2 Mathematical Model of MMCs under AC Grid Faults 234 6.2.1 AC-Side Mathematical Model 234 6.2.2 Instantaneous Power Mathematical Model 237 6.3 AC-Side Current Control of MMCs under AC Grid Faults 238 6.3.1 Positive- and Negative-Sequence Current Control 238 6.3.2 Zero-Sequence Current Control 240 6.3.3 Proportional Resonant based Current Control 242 6.4 Circulating Current Suppression Control of MMCs under AC Grid Faults 244 6.4.1 Circulating Current of MMCs under AC Grid Faults 244 6.4.2 Single-Phase Vector based Control 246 6.4.3 Two-Phase Stationary Frame based Control 247 6.4.4 Three-Phase Stationary Frame based Control 250 6.5 Summary 253 References 254 7 Protection under DC Short-Circuit Fault in HVDC System 256 7.1 Introduction 256 7.2 HB-MMC under DC Short-Circuit Fault 257 7.2.1 System Configuration 257 7.2.2 AC Circuit Breaker 258 7.2.3 Protection Thyrsitor 259 7.2.4 Protection Operation 260 7.3 DC Circuit Breaker based Protection 265 7.3.1 Mechenical Circuit Breaker 265 7.3.2 Semiconductor Circuit Breaker 266 7.3.3 Hybrid Circuit Breaker 268 7.3.4 Multi-terminal Circuit Breaker 270 7.3.5 Superconducting Fault Current Limiter 272 7.3.6 SFCL-based Current Breaker 273 7.4 Fault Blocking Converter based Protection 276 7.4.1 FB SM and HB SM based Hybrid MMC 276 7.4.2 Fault Blocking Control 279 7.4.3 FB SM Ratio 280 7.4.4 Alternative Fault Blocking SM 281 7.5 Bypass Thyristor MMC based Protection 283 7.5.1 Bypass Thyristor MMC Circuit Configuration 283 7.5.2 SM Control 284 7.5.3 Current Interruption Control 285 7.5.4 Protection Operation 288 7.6 CTB-HMMC based Protection 292 7.6.1 Circuit Configuration 292 7.6.2 SMs Operation Principle 295 7.6.3 Operation Principle for DC Fault Protection 295 7.6.4 DC-Side Current Interruption Operation 296 7.6.5 Capacitor Voltage Increment 298 7.6.6 AC-Side Current Interruption Operation 299 7.6.6 MMC Comparison 301 7.7 Summary 308 References 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