采用回复电压法分析油纸绝缘老化特征量

Analysis of Oil-paper Insulation Aging Characteristics Using Recovery Voltage Method

为将回复电压法用于电力变压器绝缘老化状态的无损诊断,通过实验室加速热老化实验,研究了不同老化程度下油纸绝缘回复电压各参数(回复电压最大值、初始斜率、中心时间常数)的变化规律;考虑到水分对回复电压参数的影响,亦对比分析了老化油纸绝缘试品干燥处理前后回复电压参数的变化。在原有回复电压参数的基础上,提出了一种新的可用于评估油纸绝缘老化状态的参数—电压相对稳定值。该参数可以反映回复电压曲线的后期信息,而且与油纸绝缘老化程度和水分质量分数都有着密切的关系。研究结果表明:回复电压各参数与老化有很好的线性关系,但水分的增加会降低其线性优度;随着老化程度的增加,回复电压最大值增大,中心时间常数减小,初始斜率增大,电压相对稳定值增大;充电时间对回复电压参数也有影响。

In order to obtain non-destructive diagnosis of the aging state of power transformer insulation by the recovery voltage method（RVM）,the variation of the RVM parameters of oil-paper insulations with the aging degrees was investigated using the accelerated thermal aging and the recovery voltage method tests.On the basis of the effect of water on RVM parameters,RVM parameters of aged oil-paper samples before and after drying treatment were comparatively analyzed.A new RVM parameter,namely,relatively constant voltage,was proposed to assess the aging state of oil-paper insulation.The new parameter is able to characterize the longer portion of the RVM curves and is highly related to both the aging stage and the moisture of the oil-paper insulation.Results show that there is a close linear relation between each RVM parameter and the aging stage,but the goodness of linearity decreases with the increase of the moisture content;With the increasing of aging degree,the maximum of RVM as well as the initial slope and relatively constant voltage increases,but the central time constant decreases;Charging time also has effect on the RVM parameters.