Developmental Research on Prospective Power Transmission System Integrated under Superconducting Environment

这一开发性研究项目旨在验证下一代超导输电的技术可能性。为此，我们试建了一个在超导环境下集成的有前景的输电模型系统。该承诺包括超导变压器、故障限流器和电缆。这三个装置被封闭在一个长比例的低温恒温器中，以保持在4.2K的液氦温度下。其传输容量目标为6kV-1500kVA。在为期3年的研究项目中，进行了6次性能试验。取得的主要成果如下：1.经多次综合试验证明，该许诺的输电能力为6千伏-1000千伏安，为世界首创。在高压侧6千伏的线路对地电压作用下，成功地维持了177安的环流。The…更多的超导限流器实际上表现出了优良的限流性能，以防止其他装置因故障电流过大而陷入异常熄火。这意味着在未来的超导输电中，通过电流限制器来实现猝灭电平的协调。建立了5m电缆段和变电站段854升整体低温恒温器的大体积液氦注入技术。由电源导线导热引起的对低温恒温器的热侵入占总侵入的75%~90%。当超导线材中淬火部分受热产生大量气泡时，液氦的动态交流耐压水平急剧下降。实验上发现了液氮击穿电压的面积效应和体积效应。用威布尔分布进行统计分析，从理论上支持了这一结果。较少

This developmental research project aims at verifying the technical possibility of superconducting power transmission for the next generation. For this purpose, a prospective power transmission model system integrated under superconduction environment, abbreviated to PROMISE, has been constructed in trial. The PROMISE consists of a superconducting-transformer, -fault current limiter, and -cable. These three apparatus are enclosed in a long scaled cryostat to keep them at the liquid helium temperature, 4.2 K.The target of its transmission capacity is 6 kV - 1500 kVA.Performance tests were carried out 6 times during the 3-year research project. Major results obtained are as follows :1. It has been proved by a few times of synthetic tests that the PROMISE has the transmission capacity of 6 kV - 1000 kVA, which is the first achievement in the world. The circulating current of 177 A was successfully sustained under impression of 6 kV of line-to-ground voltage to the high tension side.2. The … More superconducting fault current limiter actually presented excellent current limiting performance to prevent the other apparatus from falling into abnormal quenching due to large fault current. This means that quenching current level coordination is realized by the current limiter in the future superconducting power transmission.3. The injection technique of large volume of liquid helium was established for the whole PROMISE cryostat of 854 liters with the cable section of 5 m as well as the substation section. The thermal invasion into the cryostat due to heat conduction along the power leads occupies 75 to 90 % of the total one.4. Drastic degradation of dynamic ac voltage withstand level of liquid helium was actually found when a number of bubbles occurred due to heating of quenched part in a superconducting wire.5. The area and volume effects experimentally emerged on the breakdown voltage of liquid nitrogen. The results were theoretically supported with statistical analyzes using Weibull distribution. Less