应用极化谱分析油纸变压器绝缘纸板水分含量的研究

Research on moisture content analysis of insulation pressboard in oil-paper transformer using polarization spectrum

油纸绝缘电力变压器受潮会加速固体绝缘材料老化,严重影响其运行寿命,因此评估变压器的绝缘纸板中的水分含量对确保其安全可靠运行具有重要意义。变压器绝缘纸板中的水分含量是评估其是否受潮和老化的重要指标之一,然而传统的化学分析方法需要在实验室环境下进行,有些甚至需要获取变压器内部纸样。基于回复电压的极化谱方法是一种无损的绝缘诊断方法,已经被用来评估变压器的绝缘状态,特别是绝缘纸板的水分含量。本文研究了回复电压极化谱评估变压器纸绝缘的受潮的有效性,提出了评估的判断方法。试验结果表明利用极化谱的主时间常数评估其水分含量是有效的。

The insulation fault diagnosis of power transformers is important to guarantee the safe and stable operation of the power system. Moisture and aging degree of oil-paper insulated power transformer has a sure influence on its insulation property. The water content in insulation pressboard is considered as an important indicator of insulation quality and the aging condition. Although chemical analyses can provide direct information on parameters, most chemical analyses must be performed under laboratory conditions and for some chemical analyses paper samples are needed. As a non-destructive diagnostic technique, return voltage measurements based on dielectric response theory have been introduced for condition assessment of transformer insulation, especially for the evaluation of water content in transformer pressboard. The study presented in this paper aims of further investigating the reliability of using the return voltage method to assess solid insulation of power transformer. The field test results show that this method is practical, which can estimate the water content in insulation paper using its polarization spectrum and dominant time constant.