Study on Stability of Superconducting Cables for AC Application

1.多股超导电缆的暂态稳定性我们开发了一个基于三维Funite单元法的计算机程序和一个分布式电路，用来模拟三股超导电缆的暂态行为，如电缆和电缆内的温度变化，以及失超过程中电流在各股之间的分布。重点研究了铜铜矩阵对暂态稳定性的影响。根据本项目期间获得的这些结果，为交流用高稳定超导电缆的设计和开发提供了指导方针。超导圆柱形直线感应电机的发展我们设计并制造了一台具有超导初级绕组的圆柱形直线感应电机模型，以阐明交流超导绕组在实际电机运行环境中的行为(交流损耗、稳定性等)。推力特性和Ele…等基本运行特性研究了超导绕组中更多的反磁现象和力学现象。优化了一次绕组的电流分布，提高了电机的推力特性，提出了一种适合超导电机实际运行的失超保护电路。提出了用GM制冷机冷却高温超导体(HTS)的导热冷却系统的磁化技术。利用GM制冷机测量了高温超导带材(Bi2223/Ag、Bi2212/Ag带材)在超导冷却系统中的失超特性，并编制了基于有限元的计算程序来研究高温超导带材的热行为和电磁行为。利用模拟程序，讨论了制冷机冷却高温超导盘管的稳定性判据。选择发生“热失控”的电流作为稳定性判据，该电流取决于GM制冷机的冷却功率与高温超导盘管内发热量之间的关系。我们还研究了高温超导线圈在失超过程中的瞬时热行为和电磁行为，以确定实际操作中的热裕度和电流裕度。较少

1. Transient stability of multi-strand superconducting cablesWe developed a computer code based on 3D funite element method and a distributed circuit to simulate transient behaviors of three- strand superconducting cables such as temperature evolution in strand and cables, and current distribution among strands in quench process. Especially, we focused on the effect of cupper matrix on the transient stability. From these results obtained for the term of this project, the guideline for the design and development of highly stabilized superconducting cables for AC use.2. Development of superconducting cylindrical linear induction motorWe have designed and constructed a model cylindrical linear induction motor (SCLIM) with superconduting primary windings to clarify the behaviors (AC loss, stability and so on) of AC superconducting windings in a realistic operational environment of electrical rotating machines. The fundamental operational properties such as thrust characteristic and the ele … More ctro-magnetic and mechanical phenomena in the superconducting windings were investigated. And we optimized the current distribution in primary windings to enhance the thrust characteristic and proposed a newly quench protection circuit for a realistic operation of superconducting electrical machines.3. Stability Criterion for Cryocooler-cooled HTS CoilsMagnet technology of high-temperature superconductor (HTS) with conduction cooling system by GM cryocooler have been advanced. We have measured the quench characteristics of HTS tapes (Bi-2223/Ag, Bi2212/Ag tapes) with conduction cooling system by GM cryocooler and developed a computer program based on the finite element to investigate the thermal and electromagnetic behaviors within HTS tapes. Using the simulation code, we discussed a stability criterion for cryocooler-cooled HTS coils. The current at which "thermal runaway" occurs, depends on the relationship between the cooling power of GM cryocooler and heat generation within HTS coils, is chosen as a stability criterion. We also investigate the transient thermal and electromagnetic behaviors in HTS coils during a quench process to determine the thermal and current margin in a realistic operation. Less