三相同轴超导电缆瞬态热特性分析

Analysis of transient thermal characteristics of tri-axial superconducting cable

三相同轴超导电缆具有结构更加紧凑、节约带材用量、漏磁场小等诸多优点,是目前配电网应用的热点。通过对三相同轴超导电缆主要参数进行合理设计,提出在各相导体层并联铜稳定层的思路,并利用二维计算的传热分析,通过MATLAB数值计算与COMSOL建模进行联合仿真,模拟电缆瞬态热特性,分析得出了三相同轴超导电缆各导体层等效电阻的变化规律以及超导电缆各层的温度分布和故障下导体层与铜稳定层的分流情况,目的是研究在故障期间温度升高是否会导致电缆永久损坏。结果表明,加入铜稳定层后,在短时故障电流情况下,超导电缆失超,导体层失超电阻瞬间增大并随导体层电流动态变化。故障电流大部分通过铜稳定层进行流通,只有较小的一部分通过超导层,从而抑制电缆整体温度的升高,确保在保护装置动作时间内,超导带材不因温度过高损坏,因此电缆本身必须能够短时承受故障大电流。

The tri-axial superconducting cable has many advantages,such as a more compact structure,saving the amount of strip material,and a small leakage magnetic field.It is currently a hotspot in distribution network applications.In this paper,through the rational design of the main parameters of the tri-axial superconducting cable,the idea of paralleling the copper stabilization layer in each phase conductor layer was proposed,and the heat transfer analysis of two-dimensional calculation was used to conduct joint simulation by MATLAB numerical calculation and COMSOL modeling.Simulating the transient thermal characteristics of the cable,the analysis obtained the change law of the equivalent resistance of each conductor layer of the tri-axial superconducting cable and the temperature distribution of each layer of the superconducting cable and the shunting of the conductor layer and the copper stable layer under the fault.The purpose was to investigate whether an increase in temperature during a fault will cause permanent damage to the cable.The results show that after the copper stabilization layer is added,the superconducting cable quenches under short-term fault current,and the quench resistance of the conductor layer increases instantaneously and changes dynamically with the conductor layer current.Most of the fault current flows through the copper stable layer,and only a small part passes through the superconducting layer,thereby suppressing the rise of the overall temperature of the cable and ensuring that the superconducting tape is not damaged due to excessive temperature during the operation time of the protective device.The cable itself must be able to withstand high currents for short periods of time.