Research And Identification Of Partial Discharge In GIS

With the development of science and technology and the requirement of construction and environment protection, Gas Insulated Switchgear (GIS) is used in the field of power transmission and distribution widely. Because of the short insulation distance and high electric intensity, faults maybe appear in the GIS after long time operation. So it is necessary to make the state of the GIS clear. The detection of partial discharge (PD) in the GIS under the alternating voltage is one of the important approaches to know the state of the GIS. The different spectrum of PD will be produced by the different types of defects. To investigate the characteristic of the spectrum from various defects and distinguish the defects is very important to the safe operation of the GIS. A set of spectrum of PD in GIS is obtained through the experiments addressed in this thesis.In the thesis, UHF method is applied in the experiment to detect PD in the GIS. PRPD and STT chart are used to represent the partial discharge in the GIS. A set of spectrum of PD is gained through simulating various defects appearing in the GIS.Firstly, the concept and category of the PD are illustrated. Three main kinds of PD detection method– conventional method, acoustic method and UHF method– are depicted. Then some kinds of visual method to show the partial discharge are described. A set of UHF PD detection system is introduced. The main content of the thesis is about the experiment to get the spectrum of the PD in the GIS, it involves introducing the test object, simulating various defects in the GIS, detecting the PD under different SF6 pressure and different voltage. The characteristics of the spectrum of PD which are obtained from different defects in the GIS are described. The confusion among the spectrum is clarified. The result of the experiment is estimated.