Electromagnetic Response of DC Type-II SC Wires Under Oscillating Magnetic Excitations

Abstract

Type-II superconductors are expected to be extensively used in the designing of DC power grids due to their reduced use of space, high transport current capability, and nearly-zero resistive losses. Nevertheless, these systems will have to share the right of way of the currently installed AC network, reducing the costs of development associated to the superconducting cables without the need of increasing the right of way. Under the theoretical framework of the critical state model and the numerical solution of Maxwell equations in the magneto quasi-steady approach, in this paper we present a comprehensive study of the effects of applying an AC transverse magnetic field to a type-II SC wire of rounded cross section it utilized for direct current power transmission. Our numerical results can be used as a practical benchmark for determining the minimal losses and magnetic impact of DC SC lines subjected to external oscillating magnetic fields. The local dynamics of the flux front profile of current density, the resulting density of magnetic flux, the total magnetic moment of the wire, and the curve of AC losses for different conditions of DC current and transverse AC magnetic field are presented. Our results are compared with simplified analytical approaches, demonstrating the importance of considering the concomitant action of DC current and AC magnetic field by the use of numerical methods, mainly at low values of applied magnetic field relative to the intensity of transport current and the full penetration profile of current density.

Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

“…This fact sets a benchmark for which any design of rounded SC wires must be tested 53 – 56 , and from which possible pathways for the reduction of its energy losses can be assessed. Thus, in the CSM only J is constrained by , allowing to calculate the minimum energy losses per unit volume of a cylindrical wire of SC cross section area, , by 57 with the ratio between the amplitude of the transport current, , and the critical current, .…”

Computational Modelling of Russia's First 2G-HTS Triaxial Cable

“…Therefore when constructing a HTS cable, further thought needs to be put into the configuration of the cable with the three concentric phases resulting in the most compact design and therefore lowest material consumption [3]. This is especially important when considering a three phased system due to the added energy losses imposed by the alternating currents, which although could be significantly reduced by considering DC currents, depending on the amount of current being transmitted [4][5][6][7], all major transmission applications and nearly all distribution systems operate under AC conditions. Thus, for the development of three-phase networks aided by superconducting cables, one configuration of great interest is the Table 1.…”

Critical State Theory for the Magnetic Coupling between Soft Ferromagnetic Materials and Type-II Superconductors

“…However, it is precisely for this geometry where a certain amount of magnetic field has been observed in regions where no transport current is expected to flow, at least under the classical conception of the CST regime for a bare SC at self-field conditions. A significant rise and drop of the local magnetic field within the SC core near the surface of the SFM sheath has also been observed [ 41 ], both of these features being in apparent disagreement with the CST, despite its largely recognized success for all known type-II superconductors [ 10 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ].…”

“…Therefore, inspired by the pioneering research on circular magnets for high-energy particle accelerators at CERN [ 67 , 68 , 69 , 70 ] and the general CST by Badía, López and Ruiz [ 45 ], in this paper we included a multipole expansion in the integral formulation of the CST for type-II SC rounded wires [ 10 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ], allowing a direct inclusion of the magnetostatic coupling between the SC and a rounded SFM sheath ( Section 2 ). In this way, we disclose the electromagnetic behavior of the current density and magnetic field resulting from the coupling of the SC and the SFM in Section 3 , explaining with semi-analytical and numerical methods the actual causes behind the increment of the AC losses in an SC-SFM cylindrical metastructure in Section 4 .…”