Partical discharge on-line monitoring system for GIS using UHF method

Gas Insulated Substation (GIS) has obtained widespread application in power system because of its advantages of compact structure, easy maintenance, and reliable operation. However, hidden defects resulting from errors in manufacturing, shipping and other undetected scratches may lead to different degrees of partial discharge (PD) after long run of GIS. In this paper, method based on UHF is introduced to study the on-line monitor system of GIS. Firstly FDTD method is used to create models of GIS and calculate the propagation characteristic of electromagnetic wave inside the cylinder. Then on-line monitor system consist of hardware and software are introduced respectively. 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. Finally, some typical signal spectrum is given to judging test signal.