35kV/90MVA高温超导限流器低温系统

Cryogenic system for a 35kV/90MVA saturated iron-core superconducting fault current limiter

35kV/90MVA高温超导限流器的低温系统是一个开放式的液氮制冷系统,包括一个环形不锈钢杜瓦、真空绝热管、压力及温度传感器、低温阀门以及监控系统。高温超导磁体放置在杜瓦中;监控系统检测杜瓦内液氮的液面,并控制往杜瓦内进行补液。杜瓦内蒸发的氮气通过真空绝热管道直接排放到大气中。分别对不同工况下的液氮蒸发量进行了测量。进行了不通直流励磁电流、通150A的直流励磁电流、同时通交流及直流工况下的测量。测量结果表明,同时通交流及直流工况下液氮蒸发量比不通直流励磁电流时增加20%。

A cryogenic system was built as an open system for a 35kV/90MVA saturated iron- core superconducting fault current limiter which consisted of an annular cylindrical liquid nitrogen dewar, cryogenic pipes, sensors, valves, and a control unit. A HTS dc bias coil was immersed with liquid nitrogen in the dewar. The control circuit constantly monitored the liquid nitrogen level and controlled the supply of liquid nitrogen in accordance with the liquid nitrogen level change. Nitrogen vapor was directly released into the environment. Heat loss under different working conditions, such as no magnetization current, 150 A magnetization current, and on -grid condition, was measured to evaluate the performance of the system. As compared with no magnetization current of the dc bias coil, evaporation of liquid nitrogen increases about 20% under the on - grid condition.