High Temperature Superconducting (HTS) transformers are one of the potential technologies for power systems connected to offshore wind farms and stand-alone and bulk power grids. In such systems, proper fault performance of any electric device including HTS transformer is a vital factor to ensure a safe, and reliable delivery of electric power as well as power quality in electric grid. Short circuits can increase the risk of developing hot spots in superconducting tapes and as a consequence burning the windings in severe fault current cases. One important way to limit the temperature increase of the superconducting winding during short circuit is to increase the heat transfer of the liquid nitrogen (LN) during fault. In this paper, the impact of increasing the turbulence of the inlet fluid on the Hot Spot Point (HSP) temperature of superconducting windings of a 120 kVA HTS transformer was investigated during a short circuit fault. To increase turbulence and consequently, heat transfer, a device known as Perlator was used. Then, the impact of the Perlator structure and the location and angle of inlet valves were investigated on the HSP temperature of an HTS transformer, under 65 K and 77 K operating temperatures. The results indicated that by using a Perlator and adjusting valve number and location in the cryostat structure, the HSP temperature of the HTS transformer under the fault current was significantly reduced by about 46.2 K which can be vital to save the transformer from failure.

中文翻译：

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通过修改低温恒温器结构降低短路故障下高温超导变压器的温度：Perlator 和阀门位置的影响

高温超导（HTS）变压器是连接海上风电场和独立大电网的电力系统的潜在技术之一。在此类系统中，包括高温超导变压器在内的任何电力设备的正确故障性能是确保安全可靠地输送电力以及电网电能质量的重要因素。短路会增加超导带中形成热点的风险，从而在严重故障电流情况下烧毁绕组。限制短路期间超导绕组温度升高的一种重要方法是增加故障期间液氮（LN）的传热。本文研究了短路故障期间增加入口流体湍流对 120 kVA HTS 变压器超导绕组热点 (HSP) 温度的影响。为了增加湍流，从而增加传热，使用了一种称为 Perlator 的装置。然后，研究了 Perlator 结构以及入口阀的位置和角度对 HTS 变压器在 65 K 和 77 K 工作温度下的 HSP 温度的影响。结果表明，通过使用Perlator并调整低温恒温器结构中阀门的数量和位置，故障电流下高温超导变压器的HSP温度显着降低了约46.2 K，这对于挽救变压器的故障至关重要。