Study On AC Loss And Its Distribution In Like-Quasi-isotropic Conductor

As the preparation process of the second-generation high-temperature superconducting tape has become more mature,its applications in fields such as nuclear fusion and power transmission have become more extensive.However,the current-carrying and mechanical properties of a single superconducting tape are limited,and it is difficult to meet the application requirements in the field of high current and strong magnetic fields.Therefore,the parallel operation of superconducting tapes has become a trend.Internationally,such as Roebel conductors,TSTC(Twisted Stacked-Tapes Cable)conductors,CORC(Conductor On Round Core)conductors,quasi-isotropic conductors and like quasi-isotropic conductors have also been proposed.Like-quasi-isotropic conductors have high engineering current-carrying density,and its AC loss analysis and the use of efficient simulation model analysis are of great significance to its engineering applications.In this thesis,a method for preparing like-quasi-isotropic conductors is provided.Compared with conventional methods,the manufacturing method is easier to process for a wider range of occasions.This thesis proposes an accelerated formulation for studying AC losses based on finite element analysis and a method of simplifying mesh,which can efficiently analyze the complex and compact coated conductor structure.This method can improve the efficiency of mesh generation,with the advantages of low computational freedom and a wide range of applications.Using the proposed formulation and experiment,this thesis studies the influence principle of internal Q-IS pitch length and external CORC pitch on transmission AC loss.Under the premise of comprehensively considering the influence of pitch length on the critical current,the conductor structure with the best pitch length is found to maximize the AC transmission performance of the like quasi-isotropic conductor.And through the proposed formulation,the magnetic field and current distribution of each part of the conductor under different pitch length are analyzed,and the main factors to improve the AC transmission performance are found.In the aspect of AC loss under alternating magnetic field,the detection coil is used to measure the AC loss under different pitch length and frequencies of background magnetic field.The results are in good agreement with those calculated by the proposed formulation.Finally,the distribution of AC loss in each area of conductor will be studied,the method and principle of reducing AC loss will be analyzed by simulation.This thesis provides a more efficient formulation for the calculation of the AC loss of the second-generation high-temperature superconducting conductor.What's more,it also provides a simple preparation method for the industrial production of like-quasi-isotropic conductor.The result of this study can be an important theoretical basis for the application of like-quasi-isotropic conductor in electric power transmission and high field environment.