Switchgear Partial Discharge Detection And Pattern Recognition Based On TEV

With the development of economy, the power industry has made considerable progress, the stability of power systems is closely related to social stability and economic development, switchgear is an important part in power system. In order to ensure its operation, switchgear partial discharge testing has become an increasingly important issue.A variety of switchgear partial discharge detection methods were compared, including Transient Earth Voltage (TEV), which is a new detection method for its reliability, stability, strong anti-noise, etc.. So it is suitable for the detection of partial discharge in switchgear. A system of partial discharge signal detecting based on TEV was built, composed of TEV sensor, filter circuit and a wave recorder. And interference is filtered to meet the experimental requirements.To study the spread of TEV signals on the surface of metal shielding, 40 measurement points on the surface were chosen to detect the TEV signals. And the signals were analyzed to prove that the spread of TEV was affected by the shape of the shield, the gaps and the distance from the PD resource.Three typical PD models were set up in the lab for the research of pattern recognition, which were corona discharge in the air, surface discharge and the internal discharge. Spectrums of the 3 kinds of discharge were drawn and analyzed. The spectrums of Ku(△t-n)and Ku(q-n)were picked out to be the characteristic parameters.A TEV detector was manufactured and used in an 35 kV substation,obtained results show that partial discharge inside the switchgear can be detected.