大截面高压电缆金具电磁-结构瞬态耦合分析

Electromagnetic-Structure Transient Coupling Analysis of LargeCross-Sectional High Voltage Cables

电缆金具对电缆起着固定和支撑作用,电网短路时,电缆金具将承受巨大的电动力,其机械性能劣化,会对电网的稳定运行构成严重威胁。采用载荷传递的顺序耦合方法,建立电缆金具系统的电磁-结构有限元模型,以虚位移法和麦克斯韦电磁理论为基础,对电缆金具系统进行瞬态电磁场分析,得到其短路电动力和磁场分布情况,将电动力作为激励源对电缆金具进行结构瞬态动力学分析,研究其力学特性。结果表明:电缆所受瞬态电动力呈周期性变化,周期与工频周期有关,随周期增加,每个周期的瞬态电动力峰值逐步衰减;中间相电缆夹具应力水平最大,在夹具底座安装板拐角处出现了塑性变形;相对于电缆支架,电缆夹具的应力水平受静力、动力分析方法影响较小,若只对电缆夹具的应力水平做定性分析,可以采用静力分析方法,若想准确、定量分析电缆夹具的应力水平,建议采用瞬态动力学方法。电缆支架的应力水平受静力、动力分析方法影响较大,当电缆夹具采用水平“一”字形布置时,宜采用瞬态动力学分析方法。

The cable cleats play a role in fixing and supporting the cables.The cable cleats will withstand very large electromotive force when the grids are short-circuited.The deterioration of their mechanical properties may cause a serious threat to the stable operation of the grids.In this paper,the sequential coupling method of load transfer was used to establish the electromagneticstructure finite element model of the cable cleats system.Based on Maxwell's electromagnetic theory and virtual displacement method,the transient electromagnetic field analysis of the cable was performed to obtain its magnetic field distribution and shortcircuit electromotive force.As an excitation source,the transient dynamic analysis of the cable cleats was carried out to study its mechanical properties.The results show that the transient electromotive force of the cable changes periodically with the power frequency period,and the peak value of the electromotive force gradually reduced in every cycle.The stress of the intermediate phase cable fixture is the largest,and plastic deformation occurs at its corner of the fixture base mounting plate;Compared with the cable support,the stress of the cable fixture is less affected by the static and dynamic analysis methods.It recommended that the static analysis can be used for qualitative analyzing of the cable fixture stress while the transient dynamics method can be used for accurately quantitatively analyzing.As the calculated stress of the cable support is greatly affected by the analysis methods,so when the cable fixture is arranged in a horizontal linear shape,the transient dynamic analysis method should be used.