气体绝缘系统中典型缺陷的超宽频带放电信号的分形分析

要提高气体绝缘系统(GIS)放电在线监测与诊断的准确性，需要研究其典型缺陷的超宽频带放电特征。但GIS中放电频率高、频带宽，基于IEC60270标准的常规低频局部放电统计分析方法难以对放电特征进行分析。文中提出应用基于小波提取技术的放电信号的分形分析方法，对GIS中典型缺陷放电的各频段信号进行分维数计算，用分维数来量化分析GIS中超宽频带局部放电的频谱特性，发现了GIS中不同金属性表面缺陷的超宽频带放电分形特征的明显差异，对进一步将超宽频带放电检测技术用于GIS局部放电在线监测具有重要意义。

STUDY ON THE FRACTAL CHARACTERISTICS OF ULTRA-WIDEBAND PARTIAL DISCHARGE IN GAS-INSULATED SYSTEM (GIS) WITH TYPICAL DEFECTS

In order to improve the correctness of the on-line monitoring and diagnosis of partial discharge (PD) for gas-insulated system (GIS), the characteristic of the typical PD defects in GIS is studied. Since PD in the insulation of GIS has a high frequency distribution and a wide frequency band, it is hard to analyze the characteristic of the PD by using conventional PD statistic analysis method based on IEC60270. So a new signal processing method called fractal analysis of ultra-wideband PD signals based on wavelet is introduced for analyzing the characteristic of ultra-wideband discharge in this paper. The fractal dimensions of PD signals of typical defects in each frequency-band can be calculated. So characteristics of PD signals can be expressed in numerical quantities with fractal dimensions. And we obtain some discrepancy of characteristic of different PD defects on surface of insulator. Moreover, it is the base for the further study to apply ultra-wideband PD measuring to the on-line monitoring PD for GIS.