变压器油和绝缘纸老化对扩展Debye模型参数的影响研究

Aging Effects of Transformer Oil and Insulation Paper on Extended Debye Model Parameters

为研究变压器油和绝缘纸老化对扩展Debye模型参数的影响,以及确定变压器油换油时间,首先在实验室条件下对油纸绝缘试样进行130℃加速老化试验和PDC试验,然后建立不同试样相对应的扩展Debye模型,深入研究变压器油和绝缘纸老化时扩展Debye模型支路参数的变化规律,最后提出用中间时间常数分支电容变化率作为变压器的换油阈值。结果表明:变压器油主要影响扩展Debye模型时间常数小于500 s的支路参数,随着变压器油老化天数增加,油老化产物会增加油中偶极子组的转向极化及油纸界面极化,去极化电流起始部分幅值增大,较小时间常数支路电阻变小,电容变大;绝缘纸主要影响扩展Debye模型时间常数大于500 s的支路参数,随着绝缘纸老化天数增加,纸老化产物仅会增加纸内总体极化强度,去极化电流曲线末端升高,较大时间常数支路电阻变小,电容变大;扩展Debye模型中间时间常数支路电容变化率可作为换油阈值,当电容变化率大于0.36%时变压器油介损值达到4.0%,此时应进行换油处理。

To investigate the aging effects of transformer oil and insulation paper on the extended Debye model parameters and determine oil change time, accelerated aging experiment at 130 ℃ and PDC test on oil-paper insulation samples were carried out in laboratory. Then corresponding extended Debye models corresponding to every sample were established, and the changing rules of those models＇ branch parameters with aging of transformer oil and insulation paper were analyzed, respectively. It is suggested that the capacitance variation rate of intermediate time constant branch be taken as a threshold for changing transformer oil. It is demonstrated that：1）Transformer oil mainly influences the branch parameters with time constant less than 500 s,oil aging products will increase steering polarization of dipoles in oil and oil-paper interface polarization, the initial part amplitude of depolarizing current rises, the resistance of smaller time constant branch decreases while the capacitance increases; 2）Insulation paper mainly influences branch parameters with time constant larger than 500 s, paper aging products only enhance the overall polarization in paper with aging time increasing,the end of depolarizing current curve rises, the branch resistance with larger time constant decreases while the capacitance increases; and 3）The apacitance variation rate of intermediate time constant branch of extended Debye model can be taken as a threshold for changing oil. When capacitance change rate rises over 0.36% and dielectric loss of transformer oil reaches 4.0%, oil should be changed.