Development And Application Of Uhf-Ultrasonic Detection Method For Partial Discharge In GIS

With development of national economics and increase of life quality,Gas Insulated Switchgear(GIS)is widely used in the field of power transmission due to its advantage of high reliability,small area,high integration and long period of maintenance.The stable operation of GIS has become a key to the safety of power grid.Efficient detection of the GIS defects can eliminate power grid security risks and avoid unplanned outages.Partial discharge of GIS refers to the local non-penetrating discharge of insulating materials in the equipment.Long-term partial discharge at the same location will lead to deterioration or even breakdown of insulation materials.Detection of partial discharge signals is important for keeping the GIS devices running stably.In this paper,the phenomenon of partial discharge in GIS is studied.By comparing the principle and characteristics of partial discharge in different positions,the partial discharge is detected and localized by conjoint analyzing the Ultra-High Frequency(UHF)and ultrasonic singles.The research mainly consists of three parts:Firstly,the principle and production process of partial discharge defects,such as: insulation discharge,suspended discharge,tip discharge and free particle discharge,are analyzed.The characteristic spectra UHF and ultrasonic singles are compared.Secondly,principles of UHF method and ultrasonic method are studied,and the UHF-ultrasonic joint method and system are proposed.Finally,the proposed method and system are applied on the detection of the partial discharge of GIS equipment in a communication substation in Tianjin.