基于局部放电与PDC法的油膜介质老化程度研究

摘要:

电力电容器在其长达数十年的运行周期中会随时间不断老化,且以操作过电压造成的电老化为主。电容器的内绝缘——油膜介质在承受多次冲击电压后会发生绝缘性能下降,甚至出现绝缘早期失效的现象。为了对不同老化程度的油膜型介质有一个初步的判断,搭建了油膜介质老化与测试平台来对其施加不同次数的冲击电压,并分别采用交流下的局部放电法与极化去极化电流法进行实验研究。结果表明,随着油膜介质老化程度的加深,其交流下局部放电的起始放电电压是下降的,并且油膜介质PDC曲线去极化电流最大值呈上升的趋势。最后,结合油膜介质在冲击电压作用下内部分子结构的变化进行了相应的解释。

Abstract:

The power capacitor will age continuously with time in its long operation cycle of several decades,mainly caused by operating overvoltage. Internal insulation of capacitor — the oil-film dielectric will suffer from the decline of insulation state and even the early failure of insulation after it has been subjected to multiple impulse voltages. In order to have a preliminary judgment of oil-film dielectric with different aging degree,an oil-film dielectric aging and testing platform is established to apply multiple impulse voltage,and the partial discharge( PD) under AC and polarization and depolarization current( PDC)method are used respectively. The results show that the initial discharge voltage of PD decreases with the aging degree of oil film dielectric,and the maximum depolarization current of PDC curve increases. Finally,the above changes are explained by the changes of the internal molecular structure of oil-film dielectric under the impulse voltage.