大功率暂态热冲击下电阻型高温超导限流器的热力学过程研究

The over-proof problems of short-circuit current in transmission network of 220 kV and above level are serious. Based on the characteristics of zero resistance and state transition, resistive type superconducting fault current limiter (FCL) is one of the effective ways to solve short-circuit current over-proof problems. State transition trigger and large resistance appears in the non-inductive coils when a short-circuit current occurs. At the same time, large number joule heat generated. Instantaneous power up to gigawatt. The study of the thermodynamic process and laws of non-superconducting coils during the fault limit process, is one of the basic scientific problems of resistance type high temperature superconducting (HTS) FCL. Drawing up from the theory analysis and finite element modeling and Simulations, this topic carry out the study on transient high power thermal shock thermodynamic process, heat transmission mechanism, heat accumulation and performance influence rule, limiting process thermal safety margin during the limiting process and so on; They were checked and verified through the R&D several non-inductive coils and the experimental prototype and a series of experiments. Thermodynamic process during the process fault current limiting of the HTS non-inductive coil should be master systematic. The establishment of the corresponding physical model, thermodynamics, heat accumulation effect are obtained. The current limiting performance and change law, safety margin criterion with large power heat pulse were mastered. These researches and studies will provide theoretical guide and basis data for the R&D, operations of the resistive type FCL and setting reclosing time in power system with resistive type FCL.

电阻型超导限流器是解决220kV电网短路电流超标问题的有效技术方案之一。电阻型限流器中的无感线圈在故障触发限流的瞬间从超导态转变为高阻态，在故障限流的同时产生大量焦耳热，瞬时发热功率高达千兆瓦级，严重危及到电阻型超导限流器系统的稳定性和可靠性，是电阻型超导限流器研发的最大瓶颈。故障限流过程中无感超导线圈的热力学过程及其物理规律研究，是解决上述瓶颈的基础科学问题。本课题以220kV电阻型超导限流器为研究对象，开展故障限流过程中大功率暂态热冲击下系统热力学过程、热传播机理、热积累规律及其对限流过程和限流性能的影响规律研究并建立数理模型；通过无感线圈及试验样机的研制和系列实验对模型验证，并给出故障限流过程中大功率暂态热冲击下的安全热裕度判据，为电阻型高温超导限流器的设计、运行和系统重合闸时间整定等提供理论依据和工程指导准则。

短路故障是危及电力系统安全运行、导致大面积停电事故最为严重的故障之一。电阻型超导限流器利用超导体的状态转变特性，结构简单、短路电流自动触发，应用在输电网具有独特的优势。在故障限流的瞬间，利用电阻限流，发热功率巨大（峰值50kA、限流电阻5欧姆，瞬时功率高达12.5GW），在这种大功率热源的暂态冲击下，无感线圈因为迅速升温、液氮迅速汽化而形成膜态沸腾，超导绕组瞬间处于一种近似绝热状态。这种暂态高功率热冲击，不仅对电阻型HTS-FCL的限流过程和限流性能产生重大影响，还严重危及到电阻型超导限流器系统的稳定性和可靠性，是电阻型超导限流器研发的最大瓶颈。本项目研究了暂态高功率热冲击过程中，电阻型高温超导限流器瞬态生热、换热等物理模型，以及无感绕组的限流电阻的影响因素及变化规律、温升与安全判据等系列瓶颈问题，可以为提高电阻型限流器的稳定性和可靠性提供科学指导，是电阻型超导限流器研发与应用的核心基础科学问题。