CAJ | 학술논문

利用实时显微数字摄像与局部放电连续测量系统,采用典型针-板电极结构,研究了高温下不同外施工频电压作用时110kV级交联聚乙烯（XLPE）电缆绝缘中典型电树枝的形态特征、引发、生长规律及其局部放电特性。实验结果表明,温度对XLPE电缆绝缘中典型电树枝的形态、引发与生长时间具有非常重要的影响。在高温下,不同外施工频电压作用时电树枝的形态呈现出多样性的特点,50°C下典型电树枝形态为枝状、枝-松枝状和丛状,70°C下为枝状,90°C下为滞长型和枝状。高温下电树枝引发时间随外施电压升高而减小,而且在同一外施电压下,电树枝引发时间随温度升高而减小,这是由于在高温下XLPE电缆绝缘中片晶熔化,无定形相增加,介质中自由体积扩大,从而更有利于电树枝引发。研究发现在低电压（9kV）下,电树枝生长过程中由于通道电导率增加而抑制了通道内局部放电的发展,局部放电作用减小,电树枝生长速度减慢,分形维数较高;而11kV以上电压作用时,电树枝在局部放电的连续作用下呈枝状向对面电极快速生长,同时高温下XLPE弹性模量下降,击穿场强降低,局部放电作用加剧,电树枝生长明显加速,电树枝分形维数较低。
이용실시현미수자섭상여국부방전련속측량계통,채용전형침-판전겁결구,연구료고온하불동외시공빈전압작용시110kV급교련취을희（XLPE）전람절연중전형전수지적형태특정、인발、생장규률급기국부방전특성。실험결과표명,온도대XLPE전람절연중전형전수지적형태、인발여생장시간구유비상중요적영향。재고온하,불동외시공빈전압작용시전수지적형태정현출다양성적특점,50°C하전형전수지형태위지상、지-송지상화총상,70°C하위지상,90°C하위체장형화지상。고온하전수지인발시간수외시전압승고이감소,이차재동일외시전압하,전수지인발시간수온도승고이감소,저시유우재고온하XLPE전람절연중편정용화,무정형상증가,개질중자유체적확대,종이경유리우전수지인발。연구발현재저전압（9kV）하,전수지생장과정중유우통도전도솔증가이억제료통도내국부방전적발전,국부방전작용감소,전수지생장속도감만,분형유수교고;이11kV이상전압작용시,전수지재국부방전적련속작용하정지상향대면전겁쾌속생장,동시고온하XLPE탄성모량하강,격천장강강저,국부방전작용가극,전수지생장명현가속,전수지분형유수교저。
Using the real-time microscopy digital imaging and partial discharge（PD） continuous measuring system,we studied the electrical tree shape properties,initiation,growth law,as well as PD characteristics in 110 kV cross-linked polyethylene（XLPE） power cable insulation under different applied voltages at high temperature by the typical needle-plane electrode geometry.The experimental results indicated that the effect of temperature on the shape,initiation and growth time of the typical electrical trees in XLPE cable insulation was dominant.The electrical tree shapes displayed the features of diversity under different stressing voltages at an elevated temperature.The typical tree shapes at 50°C are branch tree,branch-pine tree and bush tree.The trees at 70°C are branch trees,and the trees at 90°C are stagnation-type tree and branch tree.The electrical tree initial time declined with the increase of the applied voltages,and decreased with the increase of the temperature at the same applied voltage,which was due to the melting of the lamella in XLPE cable insulation at high temperatures,and the increase of the amorphous regions and free volumes in dielectrics.It was found that the electrical tree growth rate at low voltage（9 kV） declined due to the increase of the tree channel conductivity,which suppressed the PD activity in the tree structure.The tree growth rate decreased with higher fractal dimension.However,the electrical trees grew rapidly to the counter electrode in branch-type with the continuous PD activity under higher applied voltages（≥11 kV）.Meanwhile,the elastic modulus of XLPE decreased at high temperatures,the dielectric strength declined,the effect of PD activity was fiercer,which accelerated greatly the electrical tree growth at high temperatures,and the fractal dimension of the tree was lower.