基于极化/去极化电流法的油纸绝缘时域电导模型

Time Domain Conductivity Model of Oil-paper Insulation Using Polarization and Depolarization Current Method

时域介质响应法是一种评估变压器绝缘状态的新方法,然而目前尚无公认的时域特征量能很好地表征油纸绝缘的极化特性。基于极化/去极化电流法提出了新的时域介质响应法的特征量—极化电导率,并建立了时域电导模型。搭建了用来测试油纸绝缘极化电导率的实验平台,测试了不同温度下油纸绝缘的极化电导率,并计算了油浸纸的极化电导率。实验结果表明:油隙作为油纸绝缘极化特性的影响因素之一,在测试分析过程中应当予以考虑。极化电导率随温度升高而增大,充电时间一定时,极化电导率对数与温度倒数成线性关系。极化电导率能很好地表征油纸绝缘的极化特性,与频域响应法特征量—复介电常数的关系明确,为评估油纸绝缘状态提供了新的思路和有益参考。

Time-domain dielectric response method is a new method for assessing oil-paper insulations; however, no universally accepted parameters can be used to characterize the polarization of oil-paper insulation. We proposed a parameter, namely, polarization conductivity, by polarization and depolarization-current method to model oil-paper insulation systems in time domain. An experimental system was established to measure the polarization conductivity of oil-paper insulations at different temperatures, thereby the polarization conductivity of oil-immersed paper was calculated. The results show that oil gap is one of the factors influencing the polarization characteristics of oil-paper insulation, and it should be taken into consideration in tests. The polarization conductivity increases with temperature, and its natural logarithm is linear to the reciprocal of temperature, if the charging time is constant. It is concluded that polarization conductivity characterizes the polarization of oil-paper insulation well, and has a definite relationship with complex permittivity, the frequency-domain characteristic parameter.