Development of high-temperature superconductor cables for high direct current applications / / Alan Preuß.

• VerfasserIn: Preuß, Alan,
• Place / Publishing House: Karlsruhe : : KIT Scientific Publishing,, 2021.
• Year of Publication: 2021
• Language: English
• Physical Description: 1 online resource (194 pages)

A design process for HTS DC cables was developed for high current applications. Based on the design process, a 35 kA HTS DC cable demonstrator was developed. The superconducting elements of the demonstrator were manufactured and tested individually at 77 K. Afterwards, the demonstrator cable was assembled and tested at 77 K. The assembled demonstrator successfully reached 35 kA at 77 K and self field conditions.

Table of Contents

1 Acknowledgments . I -- 2 Zusammenfassung III -- 3 Introduction . 1 -- 4 Basics of high temperature superconductivity 3 -- 4.1 Critical values of superconductivity 3 -- 4.1.1 Critical temperature . 4 -- 4.1.2 Critical current density . 4 -- 4.1.3 Critical magnetic field 6 -- 4.2 Technical superconductors . 6 -- 4.3 Second generation HTS 7 -- 4.3.1 Structure and properties of REBCO wires . 9 -- 4.3.2 Critical current magnetic field dependence 10 -- 4.3.3 Critical current temperature dependence . 11 -- 4.3.4 Critical current strain dependence . 13 -- 5 State of the art of REBCO high current transmission 15 -- 5.1 High current applications . 15 -- 5.2 High current conductor concepts . 16 -- 5.2.1 Co-axial winding concept 16 -- 5.2.2 Roebel concept 18 -- 5.2.3 Stack concepts 19 -- 5.2.4 Cross Conductor . 21 -- 5.2.5 Concept comparison . 22 -- 5.3 Summary of HTS DC cable projects 25 -- 6 Conceptual design of REBCO DC cables . 29 -- 6.1 Temperature and pressure proile . 29 -- 6.2 Fault mitigation 32 -- 6.3 Critical current calculation 33 -- 6.4 Electric insulation . 34 -- 6.5 Cable losses . 36 -- 6.6 Strain 38 -- 6.7 Design procedure 40 -- 6.8 Design study of 35 kA REBCO DC cable demonstrator . 48 -- 7 HTS CroCo Manufacturing 55 -- 7.1 Thermal stability of REBCO tapes . 55 -- 7.1.1 Experimental setup and procedure . 56 -- 7.1.2 Results 57 -- 7.1.3 Conclusion 63 -- 7.2 CroCo manufacturing process and machine . 64 -- 7.3 Manufacturer qualication . 66 -- 7.4 CroCo strand manufacturing . 70 -- 7.4.1 Preliminary CroCo manufacturing tests 70 -- 7.4.2 CroCo manufacturing 71 -- 7.4.3 CroCo residual production strain 73 -- 7.4.4 CroCo jacket . 75 -- 8 35 kA REBCO DC cable test . 79 -- 8.1 Single CroCo characterization . 79 -- 8.1.1 Electric CroCo characterization . 79 -- 8.1.2 Microscopic characterization 85 -- 8.1.3 Current distribution simulation . 88 -- 8.2 Demonstrator cable setup . 89 -- 8.2.1 Cryostat . 89 -- 8.2.2 35 kA cable demonstrator 91 -- 8.2.3 Current source and quench detection 92 -- 8.2.4 Data acquisition . 94 -- 8.3 Demonstrator cable test 94 -- 8.3.1 Cryostat cool down and warm up 94 -- 8.3.2 Cable test . 96 -- 8.3.3 CroCo performance post cable operation . 100 -- 8.4 Chapter summary and outlook 103 -- 9 Application of HTS DC cables in aluminum plants . 105 -- 9.1 Aluminum production . 105 -- 9.2 Superconducting cable systems within aluminum plants 106 -- 9.2.1 Superconducting cable use cases 106 -- 9.2.2 Cryogenic system 107 -- 9.2.3 Current leads . 110 -- 9.3 Primary circuit . 111 -- 9.4 Secondary circuit 115 -- 9.5 Aluminum bus bar . 118 -- 9.6 System comparison . 120 -- 9.6.1 General properties 120 -- 9.6.2 Annual losses and operating cost . 120 -- 9.6.3 Investment cost 123 -- 9.7 Chapter summary . 128 -- 10 Summary and outlook . 129 -- A Appendix 131 -- A.1 Order of magnitude estimation of the coolant friction 131 -- A.2 Relevant copper material properties for the use as stabilizer material . 131 -- A.3 Temperature incremental code to calculate stabilizer cross section 132 -- A.4 Darcy friction factor for smooth and corrugated pipes . 134 -- A.5 Critical current calculation of manufactured CroCos 135 -- A.6 Thermal contraction of superconducting cables . 137 -- A.7 Cryocooler capacity maps . 138 -- B List of abbreviations . 141 -- C List of symbols . 145 -- D Publications . 149 -- E Bibliography 151.