高压电缆接头压接缺陷下复合材料界面温度和应力变化规律的有限元计算

Finite element calculation of temperature and stress variation of composite interface under high voltage cable joint crimping defects

目前针对高压电缆接头压接缺陷故障发展机制主要从接触电阻过大进而引起过热的角度展开,少有加入应力耦合。然而,高压电缆接头的故障发展涉及到电-热-应力场相互耦合的复杂过程。运用有限元软件建立了220 kV高压电缆接头压接缺陷下的电-热-应力耦合模型,基于该模型主要研究了电缆接头压接缺陷等工况下复合材料界面温度和应力特性的变化规律。研究表明,电缆接头的温度和应力都随接触系数的增加而增加。相较于正常运行时,复合材料界面上的温度和应力均发生了二次畸变,其中应力畸变最明显,复合界面上靠近压接管处的应力值增长了63倍。结合220 kV高压电缆接头故障实例统计,认为压接缺陷引发复合材料界面应力的二次畸变是造成接头故障的重要原因。通过仿真计算得到了接头复合材料界面温度和应力随负荷电流和接触系数变化的多元拟合函数,可为存在压接缺陷故障评估提供经验参考。该研究对指导电缆接头的施工工艺改良和工程实际应用具有重要的理论意义及实用价值。

At present, the development mechanism of the crimping faults for high-voltage cable joints is mainly from the aspect of excessive contact resistance and thus causing overheating. However, the failure development of high voltage cable joint involves a complex process in which the electro-thermal-stress fields are coupled to each other. The electrothermal-stress coupling model of 220 kV high-voltage cable joint crimping defects is established by using finite element software. Based on the model, the variation of temperature and stress characteristics of composites under the conditions is studied of cable joint crimping defects interface. The study that temperature and stress of the cable joint increase with the increase of the contact coefficient. Compared with normal operation, the temperature and stress at the composite interface material are subject to secondary distortion, wherein the stress distortion is most obvious, and the stress value at the composite interface near the crimping pipe is increased by 63 times. Combined with the example of 220 kV high-voltage cable joint failure, it is considered that the secondary distortion of the composite interface stress caused by the crimping defect is an important cause of joint failure. Through the simulation calculation, the multivariate fitting function of the temperature and stress of the joint composite interface with load current and contact coefficient is obtained, which can provide an empirical reference for the fault assessment of crimp defects. This research has important theoretical significance and practical value for guiding the construction process improvement of cable joint and practical application of engineering.