基于电热耦合法的XLPE电缆缓冲层烧蚀特性研究

Research on ablation characteristics of XLPE cable buffer layer based on electrothermal coupling method

对高压XLPE事故电缆进行拆卸后,发现其缓冲层上均附着有烧蚀白斑。为了研究缓冲层的烧蚀特性,采用能谱仪(EDS)对缓冲层不同位置白斑的化学元素进行分析,并测量白斑缓冲层的电导率,然后基于电导率测量结果,建立高压XLPE电缆电热耦合仿真模型,对高频过电压作用下白斑缓冲层的产热特性进行计算。结果表明:缓冲层烧蚀区域的白斑为其自身析出的阻水粉,析出白斑后缓冲层的电导率明显降低。在高频过电压作用下,过电压频率越高,在缓冲层白斑局部外围产生的电阻热越大,引起的温升越高,最终可能致使缓冲层过热而烧蚀。

It is found that ablative white spots are often attached to the buffer layer by disassembling high-voltage XLPE fault cables.To study the ablation characteristics of buffer layer,the chemical elements of white spot at different positions of buffer layer were analyzed by using energy dispersive spectrometer(EDS),and the conductivity of the white spots buffer layer were measured.Then on the basis of the measurement results of conductivity,an electrothermal coupling simulation model of high voltage XLPE cable was established,and the heat production characteristics of white spot buffer layer under the action of high frequency overvoltage were calculated.The results show that the white spots in the ablative area of buffer layer are the water-blocking powder precipitated by the buffer layer,and the conductivity of the buffer layer decreases obviously after the white spots are precipitated.Under the action of high frequency overvoltage,the higher the overvoltage frequency,the greater the resistance heat generated in the local periphery of buffer layer white spot,and the higher the temperature rise,which may eventually cause overheating and erosion of the buffer layer.