Superconducting technology is potentially important as one of the future smart grid technologies. It is a combination of superconductor materials, electrical engineering, cryogenic insulation, cryogenics and cryostats. There has been no specific book fully describing this branch of science and technology in electrical engineering. However, this book includes these areas, and is essential for those majoring in applied superconductivity in electrical engineering.
Recently, superconducting technology has made great progress. Many universities and companies are involved in applied superconductivity with the support of government. Over the next five years, departments of electrical engineering in universities and companies will become more involved in this area. This book:
- will enable people to directly carry out research on applied superconductivity in electrical engineering
- is more comprehensive and practical when compared to other advances
- presents a clear introduction to the application of superconductor in electrical engineering and related fundamental technologies
- arms readers with the technological aspects of superconductivity required to produce a machine
- covers power supplying technologies in superconducting electric apparatus
- is well organized and adaptable for students, lecturers, researchers and engineers
- lecture slides suitable for lecturers available on the Wiley Companion Website
Fundamental Elements of Applied Superconductivity in Electrical Engineering is ideal for academic researchers, graduates and undergraduate students in electrical engineering. It is also an excellent reference work for superconducting device researchers and engineers.
Table of Contents
Preface xiii
Acknowledgments xv
Abbreviations and Symbols xvii
1 Introduction 1
References 3
2 Superconductivity 5
2.1 The Basic Properties of Superconductors 5
2.1.1 Zero-Resistance Characteristic 5
2.1.2 Complete Diamagnetism – Meissner Effect 11
2.1.3 Josephson Effects 15
2.2 Critical Parameters 17
2.2.1 Critical Temperature Tc 18
2.2.2 Critical Field Hc 18
2.2.3 Critical Current Density Jc 18
2.3 Classification and Magnetization 19
2.3.1 Coherence Length 19
2.3.2 Classifications 21
2.3.3 Type I Superconductor and Magnetization 22
2.3.4 Type II Superconductor and Magnetization 22
2.4 Measurement Technologies of Critical Parameters 27
2.4.1 Cryogenic Thermometers 27
2.4.2 Measurement of Critical Temperature 27
2.4.3 Measurement of Critical Current Ic 33
2.4.4 Measurement of Critical Magnetic Field 40
References 43
3 Mechanical Properties and Anisotropy of Superconducting Materials 45
3.1 Mechanical Properties 45
3.1.1 General Description of Mechanical Properties 45
3.1.2 Tensile Properties 46
3.1.3 Bending Properties 47
3.2 Electromagnetic Anisotropy 48
3.2.1 Anisotropy of Critical Current in HTS Materials 49
3.2.2 Anisotropy of Critical Current in 1G HTS Tape 50
3.2.3 Anisotropy of Critical Current in 2G HTS Tape 53
3.2.4 Anisotropy of Critical Current in Bi-2212 Wire 55
3.2.5 Anisotropy of n Value for HTS Tape 55
3.2.6 Anisotropy of Critical Current Density in HTS Bulk 56
3.3 Critical Current Characteristics of LTS Materials 57
3.3.1 Dependence of Critical Current Density of NbTi on Magnetic Field 58
3.3.2 Dependence of Critical Current Density of NbTi on Magnetic Field and Temperature 58
3.3.3 Dependence of Critical Current Density of Nb3Sn on Magnetic Field 59
3.4 Irreversible Fields of Superconducting Materials 60
3.5 Critical Temperature of Several Kinds of HTS Materials 61
3.6 Thermodynamic Properties of Practical Superconducting Materials 62
3.6.1 Thermal and Mechanical Characteristics of Practical
Superconducting Materials 62
3.6.2 Thermal Contraction of Superconducting Materials 65
References 67
4 Stability of Superconductors 71
4.1 Critical States 72
4.2 Adiabatic Stabilization 72
4.3 Adiabatic Stability with Flux Jump 75
4.4 Self-Field Stability 79
4.5 Dynamic Stability 82
4.5.1 Stability of Composite Superconducting Slab with Cooled Side 83
4.5.2 Stability of Composite Superconducting Slab with Cooled Edge 87
4.5.3 Dynamic Stability of Current-Carrying Composite Superconductor Slab 89
4.5.4 Dynamic Stability of Current-Carrying Composite Superconductor with Circular Cross-Section 91
4.6 Cryostability 95
4.6.1 Stekly Parameter 96
4.6.2 One–Dimensional Normal Zone Propagation 100
4.6.3 Three-Dimensional Normal Propagation Zone and Minimum Quench Energy 101
4.7 NPZ Velocity in Adiabatic Composite Superconductors 105
4.7.1 Longitudinal Propagation Velocity 105
4.7.2 Transverse Propagation Velocity 107
4.8 Stability of HTS Bulks 109
4.8.1 Evolution of Super-Current Density 109
4.8.2 Magnetic Relaxation 110
4.9 Mechanical Stability of Superconducting Magnets 112
4.10 Degradation and Training Effect of Superconducting Magnets 113
4.10.1 Degradation of Superconducting Magnets 113
4.10.2 Training Effects of Superconducting Magnets 114
4.11 Quench and Protection of Superconducting Magnets 114
4.11.1 Resistance Increase and Current Decay in Quench Processes 115
4.11.2 Factors Causing Quench 122
4.11.3 Active Protection 124
4.11.4 Passive Protection 128
4.11.5 Numerical Simulation on Quench 134
4.12 Tests of Stability 135
4.12.1 Flux Jump Experiments 135
4.12.2 Measurement of Quench Parameters 138
References 139
5 AC Losses 141
5.1 AC Losses of Slab 142
5.1.1 Slab in Parallel AC Magnetic Field 142
5.1.2 Slab in Perpendicular AC Magnetic Field 144
5.1.3 Self-Field Losses 144
5.1.4 Slab-Carrying DC and AC Currents Located in Parallel DC/AC Magnetic Fields 146
5.1.5 Slab-Carrying AC and DC Currents 147
5.1.6 Slab with AC Transport Current in Perpendicular AC Magnetic Field 148
5.1.7 Slab in AC and DC Magnetic Fields 150
5.1.8 Flux-Flow Loss of Slab with Combinations of AC and DC Transport Currents in Perpendicular and Parallel AC and DC Magnetic Fields 151
5.1.9 Total AC Losses of Slab with any AC/DC Current and AC/DC Magnetic Field 155
5.2 AC Losses of Concentric Cylinder 156
5.2.1 Rod in Longitudinal AC Magnetic Field 156
5.2.2 Rod in Transverse AC Magnetic Field 157
5.2.3 Rod in Transverse AC Magnetic Field and Carrying DC Transport Current 160
5.2.4 Rod in Self-Magnetic Field 161
5.2.5 Rod-Carrying AC Transport Current in AC Transverse Magnetic Field with Same Phase 163
5.2.6 Flux-Flow Losses of Rod-Carrying AC/DC Transport Currents Subjected to AC/DC Magnetic Field 165
5.3 AC Losses of Hybrid Concentric Cylinder 165
5.4 AC Losses of Concentric Hollow Cylinder in Longitudinal Field 167
5.5 AC Losses for Large Transverse Rotating Field 167
5.6 AC Losses with Different Phases between AC Field and AC Current 168
5.6.1 Slab-Carrying Current Exposed to AC Magnetic Field Parallel to its Wide Surface with Different Phases 169
5.6.2 Slab-Carrying Current Exposed to Parallel AC Magnetic Field at One Side with Different Phases 170
5.6.3 AC Losses of Slab-Carrying AC Current and Exposed to Symmetrical Parallel AC Magnetic Field with Different Phases 172
5.7 AC Losses for other Waves of AC Excitation Fields 175
5.8 AC Losses for other Critical State Models 177
5.8.1 Kim Model 177
5.8.2 Kim–Anderson Model 178
5.8.3 Voltage-Current Power-Law Model – Nonlinear Conductor Model 179
5.8.4 Combination of Kim-Anderson Model and Voltage-Current Power-Law Model 181
5.9 Other AC Losses 182
5.9.1 Eddy Current Losses 182
5.9.2 Penetration Loss in Transverse AC Magnetic Field 184
5.9.3 Twist Pitch 186
5.9.4 AC Losses in Longitudinal AC Magnetic Field 187
5.9.5 Coupling Losses 189
5.9.6 Measures for Reducing AC Losses 193
5.10 Measurements of AC Loss 194
5.10.1 Magnetic Method 194
5.10.2 Electrical Method 196
5.10.3 Thermal Method 200
5.10.4 Comparison of Electrical with Calorimetric Measuring Method 204
5.11 AC Losses Introduction of Superconducting Electrical Apparatus 204
References 206
6 Brief Introduction to Fabricating Technologies of Practical Superconducting Materials 209
6.1 NbTi Wire 211
6.2 Nb3Sn Wire 213
6.2.1 Internal Diffusion Process 213
6.2.2 External Diffusion Process 214
6.3 Nb3Al Wire 215
6.4 MgB2 Wire 216
6.5 BSCCO Tape/Wire 216
6.6 YBCO Tape 221
6.6.1 Substrate and Textured Insulated Layer 222
6.6.2 Deposition of Superconducting Layer with High Critical Current Density 222
6.7 HTS Bulk 223
6.7.1 Melt-Texture-Growth (MTG) Process 224
6.7.2 Quench-Melt-Growth (MTG) Process/Melt-Powder-Melt-Growth (MPMG) Process 224
6.7.3 Powder-Melting-Process (PMP) 224
6.7.4 Melt Cast Process (MCP) 225
References 226
7 Principles and Methods for Contact-Free Measurements of HTS Critical Current and n Values 229
7.1 Measurement Introduction of Critical Current and n Values 229
7.2 Critical Current Measurements of HTS Tape by Contact-Free Methods 230
7.2.1 Remanent Field Method 230
7.2.2 AC Magnetic Field-Induced Method 232
7.2.3 Mechanical Force Method 233
7.3 n Value Measurements of HTS Tape by Contact-Free Methods 235
7.3.1 Hysteretic Loss Component – Varying Amplitude Method 235
7.3.2 Fundamental Component Method – Varying Frequency 236
7.3.3 Third Harmonic Component Voltage Method 237
7.4 Analysis on Uniformity of Critical Current and n Values in Practical Long HTS Tape 238
7.4.1 Gauss Statistical Method 238
7.4.2 Weibull Statistical Method 239
7.5 Next Measurements of Critical Currents and n Values by Contact-Free Methods 240
References 240
8 Cryogenic Insulating Materials and Performances 243
8.1 Insulating Properties of Cryogenic Gas 243
8.1.1 Insulating Properties of Common Cryogenic Gas 244
8.1.2 Insulating Properties of Other Gases 248
8.2 Insulating Characteristics of Cryogenic Liquid 248
8.2.1 Comparison of Cryogens 248
8.2.2 Electrical Properties of Cryogens 248
8.3 Insulating Properties of Organic Insulating Films 256
8.3.1 Thermodynamic Properties of Organic Films 258
8.3.2 Resistivity of Organic Films 260
8.3.3 Permittivity of Organic Films 260
8.3.4 Dielectric Loss 260
8.3.5 Breakdown Voltage 263
8.3.6 Electrical Ageing Characteristics 267
8.4 Cryogenic Insulating Paints and Cryogenic Adhesive 269
8.4.1 Epoxy Resin 269
8.4.2 GE7031 Varnish 271
8.4.3 Polyvinyl Acetal Adhesive and other Cryogenic Adhesives 271
8.5 Structural Materials for Cryogenic Insulation 271
8.5.1 Polymer Materials 271
8.5.2 Epoxy Resin Composites 272
8.6 Inorganic Insulating Materials 273
8.6.1 Thermodynamic Properties of Glasses 273
8.6.2 Electrical Properties of Ceramics 274
8.6.3 Thermodynamic and Electrical Properties of Mica Glass 276
References 278
9 Refrigeration and Cryostats 279
9.1 Cryogens 280
9.2 Cryostat 281
9.2.1 Cryogenic Thermal Insulation 282
9.2.2 Basic Classification and Structure of Cryogenic Thermal Insulation 290
9.2.3 Structure Design of Cryostats 304
9.2.4 Cryogenic Transfer Lines and Flexible Pipes 307
9.2.5 Ultra-Cryogenic Cryostat with Dual-Cryostat Structure 309
9.3 Refrigeration 310
9.3.1 Principle of Refrigeration and Performance of Refrigerators 310
9.3.2 Choice of Refrigerator Suitable for Superconducting Power Apparatus 317
9.4 Cooling Technologies of Superconducting Electric Apparatus 317
9.4.1 Open-Cycle Cooling 318
9.4.2 Closed-Cycle Cooling by Reducing Pressure 319
9.4.3 Closed-Cycle Cooling by Refrigerator 319
9.4.4 Forced-Flow Circulation Cooling 320
9.4.5 Direct Cooling by Refrigerator 322
References 323
10 Power Supplying Technology in Superconducting Electrical Apparatus 325
10.1 Current Leads 326
10.1.1 Conduction-Cooled Current Leads 326
10.1.2 Approximate Design of Conduction-Cooled Current Lead 329
10.1.3 Demountable Current Leads 335
10.1.4 Gas-Cooled Current Leads 336
10.1.5 HTS Current Leads 340
10.1.6 Peltier Thermoelectric (TE) Effect 343
10.1.7 Gas-Cooled Peltier Current Leads (PCL) 345
10.2 Superconducting Switch 352
10.2.1 Design of LTS Switch 353
10.2.2 Design of HTS Switch 354
10.2.3 Fabrication of Superconducting Switches 355
10.3 Flux Pump 357
10.3.1 Principle of Superconducting Flux Pump 357
10.3.2 Transformer-Type Superconducting Magnetic Flux Pump 358
10.3.3 HTS Permanent Magnetic Flux Pump 359
References 361
11 Basic Structure and Principle of Superconducting Apparatus in Power System 363
11.1 Cable 363
11.2 Fault Current Limiter 366
11.2.1 Classifications 367
11.2.2 Resistive Type 367
11.2.3 Saturated Iron Core Type 368
11.2.4 Transformer Type 370
11.2.5 Shielded Iron Core Type 370
11.2.6 Bridge Type 371
11.2.7 Hybrid Type 372
11.2.8 Three-Phase Reactance Type 373
11.3 Transformer 374
11.3.1 Configuration 374
11.3.2 Advantages 375
11.3.3 Further Key Technology 375
11.4 Rotating Machine-Generator/Motor 376
11.4.1 Configuration 376
11.4.2 Advantages 377
11.4.3 Electric Machine with HTS Bulk 378
11.4.4 Applications 378
11.5 Superconducting Magnetic Energy Storage (SMES) 379
11.5.1 Principle and Basic Topology 379
11.5.2 Application in Grid System 381
11.6 Superconducting Flywheel Energy Storage (SFES) 382
11.6.1 Principle and Structure 382
11.6.2 Application in Grid System 383
11.7 Other Industrial Applications 384
11.7.1 High Magnetic Field 384
11.7.2 Low Magnetic Field 385
11.7.3 Maglev Transportation 387
References 387
12 Case Study of Superconductivity Applications in Power System-HTS Cable 389
12.1 Design of AC/CD HTS Cable Conductor 389
12.1.1 Former Size 389
12.1.2 Number of Tapes 391
12.1.3 Number of Layers 391
12.1.4 Number of Tapes on Layer 392
12.1.5 Insulation 393
12.1.6 Shielding and Protection Layers 395
12.2 Electromagnetic Design of AC/CD Cable Conductor 395
12.2.1 Range of Winding Angle (Pitch) 395
12.2.2 Design of CD Cable Conductor 396
12.3 Analysis on AC Losses of DC HTS Cable 399
12.3.1 Magnetic Field Analysis 399
12.3.2 AC Losses of HTS CD Cable Conductor 400
12.4 Design of AC WD HTS Cable Conductor 404
12.4.1 Eddy Current Loss in Cryostat 405
12.4.2 Dielectric Loss 405
12.5 Design of DC HTS Cable Conductor 405
12.6 Design of Cryostat 408
12.7 Manufacture of CD HTS Cable Conductor 410
12.8 Bending of HTS Cable 412
12.9 Termination and Joint 412
12.9.1 Termination 412
12.9.2 Joint 414
12.10 Circulating Cooling System and Monitoring System 415
12.10.1 Cooling System 415
12.10.2 Monitoring System 418
References 419
Appendix 421
A.1 Calculations of Volumetric Heat Capacity, Thermal Conductivity and Resistivity of
Composite Conductor 421
A.2 Eddy Current Loss of Practical HTS Coated Conductor (YBCO CC) 422
A.2.1 Eddy Current Loss with Transporting Alternating Current 423
A.2.2 Eddy Current Loss of YBCO CC Exposed to Perpendicular AC Magnetic Field 423
A.2.3 Eddy Current Loss Exposed to Parallel AC Magnetic Field 424
A.2.4 Iron Losses of Substrate 424
A.3 Calculation of Geometrical Factor G 425
A.4 Derivation of Self and Mutual Inductances of CD Cable 426
A.4.1 Self Inductance of Layer 426
A.4.2 Mutual Inductances amongst Layers 428
A.5 Other Models for Hysteresis Loss Calculations of HTS Cable 429
A.6 Cooling Arrangements 430
A.6.1 Counter-Flow Cooling 430
A.6.2 Counter-Flow Cooling with Sub-Cooled Station 434
A.6.3 Parallel-Flow Cooling 435
References 438
Index 439
