局部放电作用下油浸绝缘纸的微观结构及电气性能

Microstructure and Electrical Performance of Oil-immersed Insulation Paper Under Partial Discharge

对局部放电损伤过程中油浸绝缘纸的微观结构及其与电气性能的关系进行研究。使用原子力显微镜和X射线衍射仪等材料分析手段与介电谱仪、高阻仪和柱–柱电极等电气分析手段相结合的方法,分析损伤过程中油浸绝缘纸分子链结构、聚集态结构及介电常数、介质损耗因数、体积电导率和电气强度。结果表明:损伤过程中,绝缘纸结晶区比无定形区更易受到局部放电破坏;结晶度呈上升趋势且晶粒取向加强,但晶粒大小、晶体类型和二相共存结构未发生改变;结晶度升高和晶粒取向加强造成介电常数、体积电导率和介质损耗因数呈下降趋势,但电气强度呈上升趋势;结晶和取向改变了分子、离子和电子的活动性,是造成电气性能变化的重要原因。

Microstructure and relationship between microstructure and electrical performance were studied for oil-immersed insulation paper during partial discharge （PD） damage process. Material analysis apparatuses such as atomic force microscopy （AFM） and X-ray diffraction （XRD） instrument, combined with electrical apparatuses such as high-resistance meter, dielectric spectra instrument and cylinder-cylinder electrodes, were employed to investigate molecule chain structure, aggregation state structure, permittivity, dielectric loss factor, volume conductivity, and electrical strength for oil-immersed insulation paper during the damage process. The results reveal that： during PD damage process, crystalline regions of insulation paper suffer much severer damage from PD than amorphous regions; crystallinity exhibits an increasing trend and crystal grain orientation is enhanced, while crystal grain size, crystal type and two-phase-coexistent structure keep unchanged; the increase of erystallinity and the enhancement of crystal grain orientation cause permittivity, volume conductivity and dielectric loss factor to decrease, and electrical strength increase; the change in activity of molecules, ions and electrons, resulted from variations of crystallinity and orientation, is the important reason for the change in electrical performance.