基于时域介电法的变压器油纸绝缘老化特征参量分析

Aging Characteristic Parameters Analysis of Transformer Oil-paper Insulation Based on Time Domain Dielectric Method

为提取表征油纸绝缘老化状态特征参量,将时域介电法更好地应用于油纸绝缘老化状态无损检测,在实验室条件下对不同老化程度的油纸绝缘试样进行极化去极化电流法(PDC)试验,并求得其等效模型参数;然后提出系统极点Pi作为油纸绝缘老化特征参量,并建立其与油纸绝缘老化状态关系;最后验证了系统极点用于评估油纸绝缘老化程度评估的可行性。研究结果表明:扩展Debye模型参数对油纸绝缘老化程度比较敏感,特别是时间参数大于1000 s的极化支路,其时间常数随着老化时间的增加而呈现递增规律;对于时间常数大于1000 s的极化支路,极点与绝缘纸聚合度之间存在指数函数关系,且极点值越小的极化支路,拟合优度越高;优化得到的系统相对极点P与聚合度之间存在更好的指数函数关系,且此参数不受变压器几何尺寸的影响。极点验证试验验证了系统极点应用于变压器老化状态评估的可行性。

In order to extract characteristics of oil-paper insulation aging state and apply the time domain dielectric method to the nondestructive measurement of oil-paper insulation aging state better,the polarization and depolarization current(PDC)on oil-paper insulation sample with different aging state under laboratory conditions are performed;Then,the equivalent model parameters is obtained and system pole as characteristic parameter of oil-paper insulation aging state is put forward to established relationship between them;Finally,the feasibility of system poles used as oil-paper insulation aging characteristic is verified.The results show that:parameters of extended Debye model are very sensitive to oil-paper insulation aging state and time constant in branches whose time constant is greater than 1000 s increases with the aging time increasing;There is exponential function relation between polymerization degree and system poles came from branches whose time constant is greater than 1000 s.Poles with smaller value has the higher fitting goodness.The optimized relative system poles fitting better with degree of polymerization and isn’t affected by the transformer geometric dimensions.The test verifies the feasibility that system poles could be used as characteristic of oil-paper insulation aging state.