变压器油纸绝缘频域介电特征量与绝缘老化状态的关系

为了更好地将频域介电谱技术用于无损诊断变压器油纸绝缘老化状态,通过频域介电谱测试了不同老化程度油纸绝缘试品的频域介电特征量。研究了油纸绝缘试品的相对介电常数、介质损耗因数、电容、体积电导率与频率和绝缘纸老化状态的关系,在分析温度对油纸绝缘试品频域介电特征量影响规律的同时,提出了求解油浸绝缘纸活化能的新方法。结果表明:油纸绝缘试品在10 3～100Hz的频域介电特征量能反映其老化状态;不同老化程度油纸绝缘的电容C(DPt)或相对介电常数r(DPt)在10 3Hz、10 2Hz、10 1Hz的值分别与绝缘纸聚合度差值(DP0 DPt)存在二次多项式函数关系;利用油纸绝缘试品tan曲线求解出的油浸绝缘纸(DP=880)活化能为96.65kJ/mol,利用"频温平移因子"可将已知测试温度下的频域介电特征量推广到未知温度,解决了测试温度不同对FDS结果带来的影响。

Relationship Between Frequency Domain Dielectric Characteristic Quantity and Aging Status of Transformer Oil-Paper Insulation

In order to better apply frequency domain dielectric spectroscopy(FDS) in non-destructive diagnosis of transformer aging status,frequency domain dielectric characteristic quantity of the oil-paper insulation sample with different aging status are tested by FDS.The law of relative permittivity,dielectric loss factor,capacitance and volume conductivity of the oil-paper insulation sample changing with frequency and insulation paper aging status are analyzed.The temperature effects on frequency domain dielectric characteristic quantity of the oil-paper insulation sample are studied and a new method to calculate the activation energy of insulation paper is proposed.The results show that the frequency domain dielectric characteristic quantity of the oil-paper insulation sample in 10?3～100Hz can reflect the aging status of insulation paper.There is a secondary polynomial function between the values of C(DPt) or ?r(DPt) at 10?3Hz,10?2Hz,10?1Hz and the polymerization degree difference(DP0?DPt) of the insulation paper.The paper activation energy calculated by tan? curves of oil-immersed paper insulation sample(DP=880) is 96.65KJ/mol.The temperature impact on the FDS results can be solved by using the "frequency temperature shift factor" to calculate the FDS results at different temperatures.