基于末端双点解析法的变压器油纸绝缘新特征量提取及老化诊断

Extraction of New Characteristic Parameters and Aging Diagnosis for Transformer Oil-paper Insulation Based on Terminal Two-point Analytical Method

在时域介电响应法变压器油纸绝缘老化诊断的研究中,介电响应谱线的解谱一直存在不确定性,且参数计算过程复杂,间接提取的特征量物理意义较难描述。针对电路模型的确定和特征量的提取问题,提出1种诊断变压器油纸绝缘老化状态的新方法。首先采用去极化电流谱线末端双点解析法确定变压器油纸绝缘等效电路模型,提出新型极化最大直谱线,直接提取3个新特征量:极化小电阻支路数l Low_R、极化最大斜率aτmax、最大截距bτmax;经研究分析证实:油纸绝缘老化程度越严重,l Low_R越多,aτmax、bτmax越大。多台变压器实验数据分析计算表明:依据新特征量能有效诊断出油纸绝缘老化状态;确定等效电路的新方法和新特征量为诊断油纸绝缘老化提供了新的思路。

In the research of time-division dielectric response for oil-paper transformer insulation aging diagnosis, there always exists uncertainty in the solution spectrum of the dielectric response spectra, the parameter calculation process is complex, and it is difficult to describe the physical meaning of the indirect extracted feature quantity. In accordance with the problem in the circuit model determination and the feature extraction, we propose a new method to diagnose the aging condition for transformer oil-paper insulation. Firstly, a terminal two-point analytical method of depolarization current spectrum is put forward to determine the insulation equivalent circuit for transformer oil-paper insulation, a new type of polarization maximum straight spectrum is drawn, and three new characteristic parameters, such as, the number of polari- zation low resistances l Low_R , the maximum slope of polarization a τmax , and the maximum intercept of polarization b τmax , are directly extracted. It is confirmed that, the more serious the aging of oil-paper insulation is, the larger the number of l Low_R will be, and the greater value of a τmax and b τmax will be. The analysis and calculation of experimental data of several transformers prove that the aging status for transformer oil-paper insulation can be effectively diagnosed through new characteristic parameters. The new method and characteristic quantity of equivalent circuit provide a new way to diagnose the aging of oil-paper insulation.