Search

The ultra-high frequency (UHF) electromagnetic waves excited by PD (Partial Discharge) in GIS(Gas-Insulated Switchgear) are attenuated as they are affected by the GIS structure. A sensor positioned over the resin sprue in mental flange of the insulator can receive UHF signals radiated from within the GIS, which may be a way to analyze the characteristics of partial discharge. To study the effects of the resin sprue on the propagation of UHF electromagnetic waves, the finite difference time domain (FDTD) method is used. The characteristics of the amplitude and other parameters of the UHF waves in the middle of the resin sprue are studied. The resin sprue can be seen as a rectangular waveguide and the results show that outside the rectangular waveguide, the field strength component that along the conductor is much larger than the components of other two directions. There are stronger signals radiating from the resin sprue when the size of resin sprue gets larger. What's more, there are more low frequency components radiating from the resin sprue when the size of resin sprue gets larger. [ABSTRACT FROM PUBLISHER]

Ultra High Frequency (UHF) Partial Discharge (PD) location method is based on the time differences of UHF electromagnetic waves from PD source to different UHF couplers. Measuring arrival time of UHF electromagnetic waves accurately is very crucial to PD location. But the diffraction of UHF passing through windings may result in attenuation and time delay, which may lead to failure to locating PD. In order to indicate the feasibility of UHF location technique for PD sources in transformers, the influence of windings on the propagation of UHF electromagnetic wave is simulated using finite-difference time-domain (FDTD) method. Geometric analysis of UHF diffraction around windings is presented in this paper to calculate the time delay along the shortest propagation path, and an arrival time compensating method is suggested. To confirm the feasibility of the compensating method, experiments are carried out on a 220kV power transformer. It is suggested that arrival time PD inside windings can be compensated accurately. [ABSTRACT FROM PUBLISHER]