采用频域介电谱法的高压干式套管屏间局部绝缘劣化诊断

Local Inter-Foil Insulation Deterioration Diagnosis of RIP Bushing Based on Frequency-Domain Dielectric Spectroscopy Method

干式套管作为变压器的重要组成部分,屏间局部绝缘劣化时有发生,严重威胁变电站的安全运行。为进一步研究干式套管屏间局部绝缘劣化的现象,构建了实验模型,通过并联电阻的方式模拟了屏间局部绝缘劣化的现象,并基于频域介电谱（frequency-domain dielectric spectroscopy,FDS）对其在室温下进行了相应的诊断。结果表明,随着屏间局部绝缘劣化的发展,套管电容和介质损耗因素的频响曲线存在明显的过渡过程,在绝缘劣化发生的早期,工频检测方法有效性较低,而FDS的有效性则较高,且测量频率越低,对屏间局部绝缘劣化早期缺陷的检出效果越好。此外针对tanδ-f曲线中出现的快速下降段,修正了CIGRE套管模型,计算结果与实验结果一致性较好。

Resin impregnated paper（RIP） bushing is an important component of transformer, and its failure caused by local inter-foil insulation deterioration may result in phase-to-ground fault or high energy explosion, seriously threatening safe operation of substation. To carry out further study of the phenomena of local inter-foil insulation deterioration of RIP bushing, a multilayer model of epoxy impregnated paper samples is established with different parallel resistors for indicating severity of insulation deterioration. Then a diagnosis method based on frequency-domain dielectric spectroscopy（FDS） is proposed and investigated under room temperature. Results indicate that, with deterioration of local inter-foil insulation, its C-f and tanδ-f curves have obvious transition process. In early stage of local insulation deterioration, detection method of power frequency is less effective. However, validity of FDS method shows better result. In addition, CIGRE bushing model is modified for rapid descending section of high frequency band of tanδ-f curve. The calculated results with the modified model are in good agreement with experimental results.