缺陷带材对多层高温超导电缆交流损耗的影响

Effect of Defective Tapes on AC Loss of Multi-layer HTS Cables

在拉伸、扭转和弯曲条件下,超导带材会出现缺陷,从而导致临界电流的降低,为了对钇钡铜氧(yttrium barium copper oxide,YBCO)涂层导体组成的多层高温超导电缆进行缺陷情况下的数值仿真分析,建立了不同分布的缺陷带材在同一导体层和不同导体层中的仿真模型,研究了不同分布的缺陷带材在不同临界电流退化率下对多层高温超导电缆交流损耗的影响。结果表明:当缺陷发生在同一层时,交流损耗与缺陷的数量和程度有关,但与缺陷的分布无关;多层高温超导电缆在不同导体层发生缺陷时,靠近最外层缺陷越多,损耗越大,而靠近中间层缺陷越多,损耗越小;当56根超导带材中出现8根缺陷带材时,D34(40)的最大交流损耗相比于无缺陷超导带材增加了18.80%,为了避免缺陷造成的额外交流损耗,需要在实际运行中考虑保留冷却系统一定的余量。所做工作为缺陷带材对多层高温超导电缆交流损耗的研究提供了理论依据和应用参考。

Under tensile,torsional and bending conditions,the superconducting tape may become defective,reducing its critical current.In this paper,the numerical simulation analysis of multi-layer high-temperature superconducting cable composed of yttrium barium copper oxide(YBCO)coated conductors was carried out in the case of defects.Different models of defective tapes with different distributions in the same and different conductor layers were built.From these models,the effects of different distributions of defective tapes on the critical current and in turn,the AC loss in multi-layer HTS cables were analyzed.It is found that,in the case of defective tapes in the same conductor layer,the AC loss depends on the quantity and degree of defect,whereas it is independent of defect distribution.In the case of defects in different conductor layers in multi-layer HTS cable,a higher loss is observed when most defects are located near the outermost layer,whereas a smaller loss is observed when most defects are present near the middle layer.When 8 defective tapes are present in 56 tapes,the maximum AC loss is observed in C3 and C4 conductor layers with a critical current degradation rate of 40%,which is 18.80%higher than that of non-defective tapes.In order to avoid the additional AC loss caused by defects,it is necessary to consider retaining a certain margin of the cooling system in actual operation.The work provides a theoretical basis and application reference for the study of AC loss of multi-layer HTS cable with defective tapes.