Preliminary Study on Detecting PD in the GIS via Sonic Method

Jiang Yingsheng, Wu Zhirong, Nie Dexin,Sheng Guozhao, Zhang Jinliang
HIMALAYAL - SHANGHAI - CHINA

Abstract: The paper introduces results of a preliminary research in partial discharge and free particle movement from the simulated protuberance of a 220kV GIS part by the sonic detection method. The results show that the sonic detection method is very sensitive, free of the environment EMI, and capable of distinguishing different kinds of defects.

Key words: GIS, partial discharge, sonic detection , research  

1.Introduction
Relying on its outstanding performance with high reliability, GIS is gradually gaining wider application. However, its structure is compact and the shell is sealed. In addition, it holds an important position in the electric power system. Thereby, once GIS breaks, it takes a long time to repair, resulting in great loss. Developing the technology of GIS fault preventive-monitoring and diagnosing is an important method for further improving reliability and reducing maintenance cost.

The insulation monitoring is one of major fault monitoring and diagnosing  projects. Besides simply monitoring SF6 density, its basic work is to detect partial discharge. But the vitro diagnosis is the development direction of this technology. In the aspect of detecting GIS partial discharge, the sonic detection method is a method of most practical value, and studied most at present. The main kinds of GIS insulation defect are fixed type (typical representative is acicular salient on the electron) and active type defect ( free conducting particle ). Under the action of electric field, they cause shell vibration through partial discharge while the collision of particle movement directly leads to shell vibration. This paper presents results of a preliminary test in using resonant sensor to detect insulation defects