绕组和油温之间的温度梯度导致了绝缘纸的不均匀老化,绝缘纸的聚合度会影响水分在其中的分布情况。测试了5种不同聚合度绝缘纸含有相同水分含量以及不同聚合度绝缘纸浸渍于同一水分浓度绝缘油时水分扩散至稳态时的频域介电谱。制作了5种含有稳态水分含量的不同聚合度的绝缘纸叠加试样,用来模拟不均匀老化油纸绝缘含有稳态水分分布的试样,测试了该试样的频域介电谱,并采用分布阻抗的方法建立了油纸绝缘频域介电模型对其进行了数值计算。测试及计算结果表明:复介电常数实部、虚部及介质损耗随水分含量的增大而增大,随聚合度下降而增大;绝缘纸中水分含量对频域介电谱的影响要远远大于聚合度对频域介电谱的影响;不均匀老化油纸绝缘试样的频域介电谱测试结果与分布阻抗模型计算结果除在10^-3 Hz~10^-4 Hz频段内复介电常数虚部有5%的平均误差、实部有2%的平均误差外,其余频段基本相符,表明分布阻抗介电模型有效。
The temperature gradient between winding and oil will cause non-uniform aging of the paper, and the degree of polymerization (DP) of papers will affect the moisture distribution in oil-paper insulation. We tested the frequency domain dielectric spectroscopy (FDS) of five kinds of papers with the same moisture content but different DP immersed in oils with different water concentration, and five kinds of papers with different DP and different moisture contents immersed in oils with the same moisture concentration. Meanwhile, the later five kinds of paper were stacked to simulate the non-uniform aged oil-paper insulation with water content in equilibrium. We also calculated the non-uniform aged insula- tion's dielectric response after establishing an oil-paper insulation dielectric response model on the basis of the distribution impedance method. The test results indicate that the dielectric loss, the real part, and imaginary part of com- plex permittivity increase with increasing moisture content in paper and decreasing DP of paper. However, the impact of moisture content on FDS is much larger than that of DP. Except for 5% average error of real part and 3% average error of imaginary part of the complex permittivity in the frequency band of 10^-3~10^-4 Hz, the test results and calculations of non-uniform aging oil-paper model are basically consistent with each other, indicating that the proposed distribution im- pedance model is valid.