高压XLPE绝缘电力电缆放电因素及仿真分析

Discharge Factors Analysis and Simulation of High-voltage XLPE Insulated Power Cable

电力电缆结构相对单一,作为城市输变电的主线路,质量安全不可忽视。66 kV及以上额定电压等级的电力电缆交联线芯绝缘屏蔽表面采用绕包半导电缓冲(阻水)带结构,再加金属护套。缓冲层与金属护套之间的间隙等参数标准中并没有明确的要求,都是各个厂家根据自己设计的工艺进行生产制造。当电力电缆缓冲层存在某种缺陷,存在悬浮电位差等,会引起缓冲层烧蚀、白斑生成等,引起电缆局部放电,严重的甚至会引起电缆击穿故障。运用工频串联谐振试验系统和局部放电试验仪,研究缓冲层不同缺陷对电力电缆的影响,结合仿真分析,分析各影响因素的权重,优化电缆工艺,提高技术水平。缓冲层与金属护套存在较大间隙接触不良时,当场强大于气隙击穿场强就会引起局部放电;缓冲层电阻高,阻碍与金属护套电气接触时,有可能会引起烧蚀放电。通过实验结合仿真分析,为电力电缆合理化设计提供建议,达到生产制造高质量水平、更安全可靠运行的电力电缆的目的。

The power cable structure is relatively single,as the main line of urban power transmission and transformation,the quality and safety can not be underestimated.The insulation shield surface of the cross-linked line core of the power cable with the rated voltage level of 66kV and above is made of the semi-conductive buffer(water resistance)belt structure,and then adds a metal sheath.There is no clear requirement in the gap between the buffer layer and the metal sheath and other parameters,which are made according to their own design process for manufacturing.When there is some defect in the buffer layer of the power cable,there is a suspension potential difference,it will cause the buffer layer ablation,white spot formation,cause local discharge of the cable,and even serious cable breakdown failure.The power frequency series resonance test system and local discharge tester are used to study the influence of different defects of buffer layer on power cable,and analyze the weight of each influencing factor,optimize the cable process and provide the technical level combined with simulation analysis.When there is a large gap between the buffer layer and the metal sheath,the high resistance of the buffer layer prevents electrical contact with the metal sheath.Through the experiment and simulation analysis,to provide suggestions for power cable design,reasonable design,to achieve the production of high quality level,safe and reliable operation of power cable purpose.