Research On AC Losses Of CORC Superconducting Cable

Superconducting Conductor on Round Core(CORC)cable is one of the high temperature superconducting(HTS)cables.Compared with other cables,CORC cable has the advantages of high flexibility,high mechanical strength and easy manufacturing.Because of the special structure of CORC cable,CORC cable can effectively reduce the coupling current and magnetization loss in superconducting tapes.However,when CORC cable transmits alternating current or is in a changing magnetic field,AC losses will be occured,which will increase the cost of refrigeration system,reduce the operating efficiency and reduce the safety and stability of the system.Therefore,it is necessary to study how to reduce AC losses.This thesis mainly focuses on the AC loss characteristics of CORC cable.Based on the research methods of theoretical numerical calculation,finite element simulation and experimental measurement,this thesis mainly completes the following work:(1)Based on the finite element method,a two-dimensional numerical simulation model of AC loss of HTS tape is established.In this thesis,AC loss is calculated based on H formulation.The simulation results are compared with the theoretical calculation formulation of AC loss to verify the correctness of the simulation model.(2)Based on the finite element method,a three-dimensional numerical simulation model of AC loss of CORC cable is established.In this thesis,the E-J exponential characteristics of H formulation and Kim critical state theoretical model are used to calculate AC loss.The simulation analysis results are compared with the experimental measurement results to verify the validity of the simulation model.The influences of different round core tube materials,different copper tube thicknesses and different copper tube diameters on the AC losses of the CORC cables are calculated and analyzed by using the simulation platform.(3)Based on the electrical measurement method,the AC loss experimental measurement platform was built independently,the laboratory hardware equipment was connected and the Lab VIEW software was designed,and the AC loss of HTS tapes was measured.Compared with Norris formulation,the effectiveness of the measurement platform was verified.The influence of different current frequency and different thickness of reinforcing layer on the AC loss of superconducting tapes is also discussed.The critical current of the tape is measured by the laboratory critical measurement system.(4)The CORC cable samples were made,and the critical current of the CORC cable was measured experimentally.AC loss of CORC cable was measured by the self-built AC loss measurement platform,and the influence of different frequencies on the AC loss of the CORC cable was discussed.(5)The influence of copper tube filamentation on AC loss of CORC cable is calculated and analyzed by using the built 3D simulation model,and the effect of the shape and number of etched grooves in filamentation on reducing AC loss of CORC cable is analyzed.