基于电磁-热耦合的XLPE电缆缺陷暂态温度分布研究

Study on transient temperature distribution of defects in XLPE cables based on electromagnetic-thermal coupling

针对10 kV电缆常见的3种缺陷,本文建立了三维电缆缺陷模型并进行电磁-热耦合温度场分析,研究3种缺陷电缆的暂态温度模型,分析不同工作电流与不同敷设条件对3种缺陷电缆温度的影响。结果表明:缺陷对电缆的危害从大到小排序依次为金属尖端缺陷、气隙缺陷、划痕缺陷;在相同载流量的情况下,金属尖端缺陷处温度高于其他两种缺陷处温度;确定了电缆在出现缺陷时隧道敷设的散热效果最好;无缺陷试样电缆内部温度从线芯至外护套沿径向逐渐降低,在缺陷的作用下电缆内部温度场发生畸变;缺陷电缆线芯温度与外护套温度的拟合系数、电缆缺陷处温度与电缆线芯温度的拟合系数均接近1。仿真拟合结果为电缆缺陷的判断与识别提供了理论支撑。

In view of three common defects of 10 kV cables,three-dimensional cable defect models were established and conducted electromagnetic-thermal coupled temperature field analysis to study the transient temperature models of three defective cables.The effects of different operating currents and laying conditions on the temperature of three defective cables were analyzed.The results show that the harm of defects on the cable ranked from high to low is metal tip defect,air gap defect,and scratch defect.Under the same current carrying capacity,the temperature at the metal tip defect is higher than that at the other two defects.It is determined that the heat dissipation effect of tunnel laying is the best when the cable has defects.The internal temperature of the cable without defects decreases gradually from the core to outer sheath in the radial direction,and the internal temperature field of the cable is distorted under the action of defects.The fitting coefficients between core temperature and outer sheath temperature of the defective cable,and the fitting coefficients between temperature at the defect and the core temperature of cable are both close to 1.The simulation fitting results provide theoretical support for the judgment and identification of cable defects.