Search

In this paper, the ac losses mainly about hysteresis loss in the preliminary design of Rutherford cable (Rfc) made from high-temperature superconducting (HTS) Quasi-isotropic Strands (Q-ISs) are evaluated by numerical simulations. A 2-D structure for Rfc including 10 Q-ISs is proposed. Then, transport ac loss in the cable made from Q-ISs under different frequencies and amplitudes of transport currents, and the magnetization loss under external ac magnetic fields of different magnitudes with different orientations are separately calculated using T-A formulation at 77 K. Additionally, the simulated results of the Rfc are compared with those of a directly stacked conductor (DSC). The results show that the transport ac loss of the Rfc made from Q-ISs is smaller than that composed of DSCs. The magnetization loss of Rfc made from Q-ISs is also smaller than that of DSCs in some certain range of external field orientation. The proposed Rfc is a potential and promising solution for superconducting cables for ac applications of feeder line and bus with high current capacity.

In practical applications, the stacking pattern of superconducting tapes has vital influence on the loss and the current quality of superconducting conductors during the current transmission. Based on the structure of quasi-isotropic superconducting strand (Q-IS), the distribution of magnetic field at the ends of the strand is simulated and measured. In order to investigate the distinction for different structures, a kind of quasi-isotropic superconducting strand made by REBCO coated conductors (CC) only (Q-IS1), and the other kind of quasi-isotropic superconducting strand stacked by copper tapes and REBCO CCs alternately (Q-IS2) are studied. Results show that Q-IS1 has better current transfer performance.

The critical current of a REBCO tape is a crucial factor in describing its quality. The orientation of applied field has a significant impact on it which is different under different temperatures and amplitudes of applied field. In this paper, we construct a cryogen-free Ic measurement system with a wide range of temperature (20–100 K), magnetic field (0–3 T), angle of the magnetic field (0°–360°), and current (0–875 A). The results of the measurements demonstrate that the system can accurately measure the critical current. The magnetic field angle dependency curves of three types of REBCO tapes (MOCVD, MOD, and PLD) are measured. The offset angles near θ = 0° and 180°, impact of the parallel field's direction, and uplifts near θ = 90° appear in all REBCO tapes. The effect of temperature and magnetic field on these characteristics depends on the tape's technique. These features are essential in the selection of REBCO tapes for different applications and the structure design of HTS facilities.

Self-shielding high-temperature superconducting (HTS) DC cables made of REBCO tapes can almost eliminate the magnetic field within the cable layers, which can improve the uniformity of current distribution and magnetic field. In this paper, two self-shielding HTS DC cables made of REBCO tapes with different-direction currents under fault current are simulated based on H-formula and external circuit model. And the abilities of limiting fault current are also compared. Results show the design of “+−+” can limit DC fault currents better in restricting both the rising rate and the peak value of fault current. Self-shielding HTS cable can inhibit fault currents due to its magnetic shielding. And the “+−+” configuration performs better for limiting DC fault current than the “+−+−” configuration.

Compared with high temperature superconducting (HTS) ac cable, HTS dc cable has the advantages of large transmission capacity, low ac loss and strong controllability. Self-shielded HTS dc cables with different current directions in adjacent layers can reduce the magnetic field interaction between layers, so as to increase the critical current of the cables and reduce ripple loss. In this paper, a novel self-shielded dc cable is proposed, which is made of REBCO tapes with different widths. The magnetic field distribution, ac ripple loss of the novel cable and Ampere force are studied based on T-A formula. The results show that the wider outer tapes can counteract the magnetic field in the inner tapes, and the novel self-shielded dc cable has smaller magnetic field between layers, lower ripple loss and smaller Ampere force than the previous self-shielded dc cable made by tapes with the same width. This novel self-shielding structure provides a new idea for the design of dc cable for large dc applications.

High-temperature superconducting (HTS) magnets have huge advantages for providing strong magnetic fields within a compact structure and saving energy. However, it is almost impossible for them to operate in persistent current mode (PCM) since the soldering technique without resistance is unavailable. A gourd-shape HTS plate-loop configured by partial central cutting REBCO HTS tape with a function of flux density amplification is proposed. It consists of two circular holes with different diameters connected by a single slit. The conventional copper coil with an iron core is positioned within the big loop. This arrangement allows for a higher flux density in the small loop compared to the big loop by the field cooling (FC) exciting method, which can be seen as a form of flux density amplification. Flux density amplifying function of the gourd-shape HTS loop is confirmed by performing experiments and numerical simulation in 77 K. The results suggest that the gourd-shape HTS loop design offers significant advantages. It can provide higher magnetic field strength than the big loop, operate in PCM without current leads, and have a wider operational temperature range than LTS magnets. These attributes make it highly promising for various applications, such as magnetic resonance imaging (MRI), accelerator technology, and other fields that require high magnetic fields. Additionally, this design has the potential to lower manufacturing costs and facilitate easier implementation of HTS permanent magnets, thus promoting the widespread utilization of HTS technology in the industrial sector.