Interface Charge Accumulation Characteristics and Dynamic Process of Paraffine-Base and Naphthene-Base Transformer Oils under DC and Polarity Reversal Voltage
Zhang Shuqi1, Zhao Xiaolin2, Qi Bo1, Liu Xin3, Li Chengrong1
1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China; 2. China Electric Power Research Institute Beijing 100192 China; 3. State Grid Anhui Ultra High Voltage Company Hefei 230000 China
Abstract：Regarding naphthene-base transformer oil (N oil) and hydroisomerized paraffine-base transformer oil (P oil) as the research objects, the dynamic process of space electric field and interface charge of oil-pressboard insulation under DC voltage and polarity reversal (PR) voltage was obtained. Under constant DC voltage, the amount of charge accumulation at the interface of P oil-pressboard was 86% of that of N oil, and the rate of charge accumulation was less than 30% of that of N oil. Under the PR voltage, polarity reversal time had a great influence. While the polarity reversal time was 1s, the electric field of P oil was 0.54 times that of N oil after the first reversal, and while the polarity reversal time was 120 s, the electric field of P oil was 1.65 times that of N oil. The influence of oil character on the converter transformer insulation is revealed from the point of view different from the conventional performance indexes such as physical, chemical and electrical characteristics. It is that different types of transformer oil have different mobility of positive and negative ions, resulting in different distribution patterns at the oil-pressboard interface. It provides a new method and guidance for selecting transformer oil reasonably and optimizing insulation design of converter transformer.
2022, Vol. 37 
