纳米MMT改性绝缘纸板局部放电特性研究

Partial discharge characteristics of nano-MMT modified insulating pressboard

为抑制换流变压器油纸复合绝缘结构中的局部放电现象,利用纳米掺杂手段制备出纳米蒙脱土(Montmorillonite,MMT)改性绝缘纸板。实验测量了纳米掺杂对改性纸板的介电参数的影响,研究了其在两种电极结构下的局部放电特性,借助软件仿真分析了纳米改性对局部放电的抑制机理,并进一步探究了其对油纸复合绝缘结构击穿特性的影响。试验结果表明,改性纸板电导率随纳米掺杂比例的上升呈上升趋势,介电常数随之先下降后上升,击穿场强则先上升后下降,二者在纳米掺杂比例为1%时分别达到最低值和最高值。采用该浓度改性纸板会使油纸绝缘结构的局部放电起始电压升高,且相同电压下的最大放电量降低。仿真分析得出其对局放实验中油纸复合绝缘结构电场分布具有均化作用,并最终改善击穿特性。

In order to restrain partial discharge phenomenon of oil-paper insulation structure in convertor transformer,the nano-MMT modified insulating pressboard is developed by nano-doping method.The influence of nano-doping on dielectric parameters of modified pressboard is measured,and the partial discharge characteristics of the modified paperboard under two electrode structures are studied.Meanwhile,the inhibition mechanism of nano-doping on partial discharge is analyzed with the help of software simulation,and its impact on the breakdown characteristics of oil-paper insulation structure is further investigated.The results show that the conductivity of the modified pressboard rises with the increase of nano-doping ratio,while the relative permittivity falls firstly and then rises,and the breakdown field strength rises firstly and then falls.When the nano-doping ratio is 1%,the relative permittivity and the breakdown field strength reach the lowest value and the highest value respectively.The initial partial discharge voltage will increase and the maximum discharge quantity under same voltage level will decrease in oil-paper insulation structure by using nano-doping pressboards at this ratio.Moreover,it helps to homogenize the electric field distribution of oil-paper insulation structure in partial discharge experiments,and finally contributes to the improvement of breakdown characteristics.