Research On Magnetic Field Distribution And Ripple Loss Of High Temperature Superconducting DC Cable With Medium/Low Voltage And Large Current

In this paper,a global magnetic leak-free high temperature superconducting DC cable for medium/low voltage and large current is studied.The design of this new cable is not limited by the number of layers.The magnetic fields of adjacent layers cancel each other,which can weaken the interaction of magnetic fields between layers,and thus effectively improve the current carrying capacity of the DC cable.In this paper,the global magnetic leak-free high temperature superconducting DC cable is systematically studied:According to the existing design methods and principles and the characteristics of the multi-conductor layer structure of the global magnetic leak-free cable,the central skeleton,the number of conductor layers,the number of tapes in each layer,the winding pitch,the insulation material and the thickness of the global magnetic leak-free high temperature superconducting DC cable are designed.The global magnetic leak-free cable has strong current-carrying capacity and many conductor layers.In order to make full use of the outer superconductor,the global magnetic leak-free cable adopts the principle of equal ratio for iterative calculation of winding angle.In this paper,the four-lead method for measuring critical current is introduced in detail,and the critical current of the two mm wide REBCO superconducting tape is obtained through experiments.In this paper,two numerical algorithms(H algorithm and T-A algorithm)aiming at the special electromagnetic characteristics of high temperature superconducting materials and a self-consistent model which can quickly solve the critical current of global magnetic leak-free cable are introduced.Aiming at the disadvantage that the magnetic field of odd-layer conductor is larger than that of even-layer conductor of magnetic leak-free cable,this paper puts forward the solution of global magnetic leak-free current transmission mode(the two adjacent layers of the cable current are in opposite directions with different sizes,and the overall positive and negative currents are in opposite directions with equal sizes).The global magnetic leak-free optimization method can effectively improve the uniformity of magnetic field distribution from the perspective of changing the current distribution between layers by adjusting the quantity and layout of each layer tape of cable.Aiming at the disadvantage of uneven distribution of magnetic field along the width of the superconducting tape of the global magnetic leak-free cable,this paper proposes the optimization method of superconducting tape filamentation,which can significantly improve the uniformity of magnetic field in the each layer by changing the current distribution in the each layer of cable.In this paper,T-A algorithm is used to verify the rationality and correctness of two methods of optimizing the magnetic field distribution of cable,namely global magnetic leak-free and tape filamentation.The results show that both methods can uniform the magnetic field distribution,increase the critical current and reduce the ripple energy loss.The research content of this paper provides a reference for the design of the structural parameters of the global magnetic leak-free cable,and provides a thought for the calculation and evaluation of the critical current and ripple loss of the magnetic leak-free high temperature superconducting DC cable.The two methods of optimizing magnetic field of cable can make the magnetic leak-free cable better meet the requirements of the actual engineering transmission.