Research on GIS corona discharge PRPD pattern based on optical detection

In order to study the detection effect of optical detection on corona discharge in gas insulated switchgear (GIS), a photomultiplier tube (PMT) based optical detection method test platform is built. The needle-plate electrode is used to simulate corona discharge. An oscilloscope is used to collect the optical signal of corona discharge, a high-voltage probe is used to obtain the reference voltage, and the phase resolved partial discharge (PRPD) pattern of the optical signal is analyzed. The results show that with the development of partial discharge (PD), the PRPD pattern can obviously unfold in different stages, which indicates that the optical detection for GIS has high detection sensitivity and good discrimination of the severity of discharge development. By combining the results of the PRPD pattern and previous studies, it is inferred that the negative half cycle discharge of AC corona discharge mainly depends on the electron avalanche ($\alpha$-process) and the secondary electron avalanche on the cathode surface ($\gamma$-process), and the light radiation is mainly excitation radiation and bremsstrahlung. The positive half cycle mainly depends on spatial photoionization (anode streamer), and the light radiation mainly consists of recombination radiation, excitation radiation and bremsstrahlung. This paper can provide a reference for the application of photoelectric devices used in GIS.