油纸不均匀热老化对变压器频域谱的影响研究

Research on Influence of Uneven Thermal Aging of Oil Paper on Frequency Domain Spectrum of Transformer

油浸式电力变压器内部绝缘结构由于运行工况改变,会导致热老化不平衡的情况。为进一步研究绝缘纸不均匀老化对频域参数的影响,对制备样品进行叠放分组,针对不同老化样品开展多组频域分析,对比得出试品受热不均匀给样品频域谱的作用情况和对试品水分含量评估的作用。结论如下:均匀老化和不均匀老化样品的频域参数在不同组测试时幅值均随着频率的变大而逐渐下降,但在不同频率段内的变化趋势则不尽相同;受样品内部水分的作用,老化均匀样品频域曲线随水分含量的升高趋向于高频方向,介电常数实部、虚部大小伴随纸样品中水分含量升高而变大;绝缘纸受热均匀可对评估样品内部含水量影响较小,而受热不均匀时对测试结果影响较大,不利于含水量评估。

The oil paper insulation system of oil immersed power transformer would result in uneven heating due to the change of operation conditions.In order to further study the influence of uneven aging of insulating paper on the frequency domain parameters,the samples are stacked and grouped,and the frequency domain analysis is carried out for different aging samples.The influence of uneven heating on the frequency domain spectrum of samples and the impact on the moisture content evaluation of samples are compared.The conclusions are as follows.The amplitudes of the frequency domain parameters of the homogeneous aging and the inhomogeneous aging samples decrease with the increase of the frequency in different groups of tests,but the change tendency in different frequency ranges is not the same.Affected by the internal moisture of the samples,the frequency domain curves of the aged homogeneous samples move to the high frequency direction with the increase of the moisture content,and the amplitudes of the real part and the virtual part of the dielectric constant follow the paper samples.The moisture content of the sample increases with the increase of the moisture content.Even heating of the insulating paper has little effect on the internal moisture content of the evaluation sample,while uneven heating has great influence on the test results,which is not conducive to the moisture content evaluation.