Study of partial discharge monitoring system for GIS based on UHF method

GIS has the advantage of compact structure, small size and high reliability, and now it is widely used in power system. But partial discharge (PD) in GIS will cause further deterioration of insulation and finally cause the huge losses of power system. So it is necessary to detect the PD signals in GIS. In this paper, firstly FDTD method is used to create models of GIS and calculate the propagation characteristic of electromagnetic wave inside the cylinder and draw the conclusions that the energy of PD signals is focused on GHz. So it is practicable to monitor the PD using the UHF method. Then PD monitoring system for GIS based on UHF method is introduced. The monitoring system can detect and monitor the real-time PD peak values and phase positions, and finally it calculated the spectrograms such as N-φ, H_n(φ) and φ-Q-N. Using the spectrograms one can get the level of PD and then take the measures to handle the fault.