面向高温超导同步调相机的应用需求，本论文围绕高转速高温超导磁体技术、旋转低温氦气分布式冷却方法、快速励磁调节过程磁体热稳定性等关键问题，开展了高温超导同步调相机转子磁体及低温研究，研究工作包括：1. 从超导材料、电磁性能、低温可靠性、结构安全以及状态感知等多维度对REBCO高温超导转子磁体进行了设计研究。针对REBCO涂层导体环氧浸渍的破坏风险，本论文提出了REBCO磁体无环氧浸渍工艺。为了提高转子磁体低温性能，本论文在转子磁体间设计了分布埋入式传导冷却结构，并制作了模型磁体进行低温可靠性验证。2. 针对磁体叠分布埋入式传导冷却结构的需求，本论文从降低转子冷却管路的流动阻力和提高返流通道的流动阻力两方面出发，研究了旋转低温氦气循环冷却系统的设计方法。一方面研究了氦气管道阵列的对流换热热阻与流动阻力的相互影响，提出了转子低温管路的设计方法；另一方面研究了返流通道流动阻力增强方法，开发了氦气旋转传输装置，并进行了常温试验验证。3. 本论文开发了一台300 kvar高温超导同步调相机试验平台，对转子磁体开展了低温与电学性能试验。试验中，转子磁体冷却至25 K以下，实现了在1500 rpm、200 A下接近100 kW的功率输出，以及在1500 rpm下从170 A到200 A的快速励磁试验。基于上述设计研究与试验验证，本论文取得的主要创新成果包括：1. 提出了采用低表面粘附力材料真空浸渍、高机械强度结构预应力增强、分布埋入式管道传导冷却的无环氧浸渍REBCO磁体技术，解决了 REBCO 磁体在高应力作用下浸渍引起的脱层破坏、快速励磁调节过程中结构件发热损耗大的问题，技术可靠性在磁体模块试验、300 kvar电机试验中得到了验证。2. 建立了旋转低温氦气循环冷却系统的设计方法，并开发出了低温氦气旋转传输装置，解决了低温氦气在电机转子与静止低温制冷单元之间的双向旋转传输问题，实现了300 kvar电机1500 rpm转速下稳定冷却。3. 开发了基于REBCO导体的高温超导同步调相机转子磁体，并应用于300 kvar高温超导同步调相机中，通过高转速下的快速励磁试验，验证了REBCO导体应用于同步调相机场景的可行性。
Facing the requirements of high-temperature superconducting (HTS) synchronous condenser application, this dissertation is focused on key issues such as HTS magnet technology, rotor helium gas circulating cooling circuit, and superconducting magnet thermal stability during rapid excitation adjustment. Main research work includes: 1. The design and fabrication process of $\rm RE_1Ba_2Cu_3O_{7?δ}$ (REBCO, RE:Rare Earth) rotor magnet. To avoid the risk of REBCO coated conductors damage caused by epoxy impregnation, this dissertation proposed a paraffin impregnation process to replace the epoxy impregnation process. A distributed helium-gas tube conduction cooling structure was designed to improve the cryogenic performance of the epoxy-free impregnation magnets and a magnet module was fabricated and tested to verify the new fabrication process and cooling structure. 2. The design method of rotor low-temperature helium circulating cooling circuit was studied from two aspects: how to reduce the flow resistance of rotor cooling pipeline and how to enhance the flow resistance of the return path of the helium rotating transfer device. On the one hand, parametric studies of pipeline structures regarding the thermal resistance and flow resistance were carried out, and the design method of rotor cooling pipelines was proposed; On the other hand, the method of enhancing the flow resistance in the return path was studied and the helium rotating transfer device was developed according to the study. 3. A synchronous condenser rotor based on REBCO conductors was developed and assembled in a 300 kvar high-temperature superconducting synchronous condenser (HTSSC). The cooling testing and electrical performance testing of the rotor magnet were carried out. The results showed the rotor magnet was cooled below 30 K, and the output power of the machine reached nearly 100 kW with a transport current of 200 A at 1500 rpm. During the rapid excitation experiment, the magnet was successfully ramped from 170 A to 200 A in 1 second at 1500 rpm. Based on the above research, the main innovative achievements of this dissertation include:1. The epoxy-free impregnation method for REBCO magnet was proposed, which could be used to avoid the risk of conductors delamination caused by epoxy impregnation at cryogenic temperature. The technical feasibility has been verified in the magnet module testing and the 300 kvar HTSSC testing.2. The design method of the rotor low-temperature helium gas circulating cooling circuit was established, and the key device--a low-temperature helium gas rotating transfer device was developed, which enabled the low-temperature helium gas bidirectional rotating transfer between the rotor and the static cryogenic unit, and maintained the thermal stability of the rotor magnets in the 300 kvar HTSSC prototype during rotating excitation tests.3. A high-temperature superconducting rotor based on REBCO conductors was successfully developed and applied in the 300 kvar HTSSC prototype. Through the rapid excitation testing at high rotation speed, the feasibility of applying REBCO conductors in the synchronous condenser field was verified.
