基于温度测量和气体分析的高压电缆缓冲层烧蚀故障检测技术

Detection Technology of Buffer Layer Ablation Failure in High Voltage Cables Based on Temperature Measurement and Gases Analysis

高压电缆缓冲层烧蚀是近年频繁发生的故障,严重威胁电缆系统的安全运行。为此提出一种基于温度测量和气体分析的技术,用以检测缓冲层烧蚀故障。实验室条件下的烧蚀实验表明电缆烧蚀部位存在发热现象,并伴随有甲烷(CH_(4))、乙烷(C_(2)H_(6))、乙烯(C_(2)H_(4))、乙炔(C_(2)H_(2))、一氧化碳(CO)、二氧化碳(CO_(2))等产物的释放。有限元仿真研究发现电缆内的电接触不良会导致局部高温,超过缓冲层的起始分解温度进而引起材料破坏。分析认为实验中测得的烧蚀气体产物来自缓冲层的受热分解过程。将上述结果应用于北京地区的实际电缆线路检测,通过红外测温发现某电缆外护套存在异常温度升高现象,并在电缆内部检出了CH_(4)、C_(2)H_(6)、C_(2)H_(4)等气体成分。随后解体观察到该段电缆存在烧蚀特征,验证了该方法的正确性和可行性。该研究结果表明温度测量结合气体分析的技术可以检测出高压电缆缓冲层烧蚀故障,有望在实际电缆线路中获得广泛应用。

The buffer layer ablation of high voltage cables is frequently reported in recent years,which threatens the safe operation of cable systems.As a result,a method is proposed for detecting the buffer layer ablation failure based on tem-perature measurement and gases analysis.The temperature rise was detected at the cable ablative site in laboratory,which was accompanied by the release of gas products,such as CH_(4),C_(2)H_(6),C_(2)H_(4),C_(2)H_(2),CO,and CO_(2).The finite element simu-lation revealed that partial high temperature exceeding the initial decomposition temperature of the buffer layer could be induced by poor electrical contact in cables.Therefore,the ablative gas products were released by the thermal decomposi-tion of buffer layer.Subsequently,the above method was applied on the failure detection of practical cable lines in Beijing area.An abnormal temperature rise was found in a cable outer sheath and the gas components such as CH_(4),C_(2)H_(6),C_(2)H_(4) were detected.The buffer layer ablation failure was observed by cable disassembly,verifying the feasibility of this meth-od.Relevant results show that the technology based on temperature measurement and gases analysis can detect the buffer layer failure of high voltage cables and have prospects of wide application in the practical cable lines.