Quench/Thermal Runaway Detection and Protection Technique for Conduction-cooled HTS Conductors

超导储能系统(SMES)有望在高可靠的电力系统中发挥重要作用。为了减小体积和降低成本，对Bi2212高温超导线材的SMES系统进行了研究。为了保证超导SMES的可靠运行，需要对Bi2212线圈的热失控特性进行评估和了解。本课题从上述观点出发，研究了4K-GM制冷机系统的Bi2212超导线圈的热失控特性。在5K到20K的不同环境温度下，测量了高温超导螺线管线圈的温度和电压分布，得到了负载波动补偿等典型电流模式。在电流模式下，螺线管线圈最内层的电压迅速升高，高温超导线圈达到热失控。然后，进行了导热冷却条件下的热分析，包括导热、导热和换热。通过热分析再现了实验结果，并对热失控特性进行了评价。热失控的临界电流随温度的降低而增大，在10K以下达到饱和。在此基础上，找出了评价导电冷却高温超导线圈热失控特性的关键参数，并提出了高温超导SMES系统的诊断判据。

Superconducting Magnetic Energy Storage (SMES) is expected to play a significant role in a highly reliable electric power supply system. For size and cost reduction, conduction-cooled SMES system with Bi2212 HTS wire has been investigated. For the reliable operation of conduction-cooled HTS SMES, thermal runaway characteristics of Bi2212 coil should be evaluated and understood.From the viewpoint mentioned above, this research project investigated thermal runaway characteristics of conduction-cooled Bi2212 HTS coil with 4K-GM cryocooler system. We measured temperature and voltage distribution of the HTS solenoidal coil for typical current patterns of load fluctuation compensation and so on at different ambient temperatures from 5K to 20K. The voltage in the innermost layer of solenoidal coil increased rapidly under the current pattern and the HTS coil reached thermal runaway. Then, we carried out thermal analysis including heat generation, conduction and transfer under conduction-cooling condition. We reproduced the experimental results by thermal analysis, and evaluated the thermal runaway characteristics. The critical current for thermal runaway increased with the temperature decrease and saturated at the temperature lower than 10K. Furthermore, we found key parameters for evaluation of thermal runaway characteristics of conduction-cooled HTS coils, and suggested a criterion for the diagnosis of HTS SMES system.