Partial discharge appears when GIS is contaminated by the defects such as needle protrusion

metallic particle

etc.

exciting ultra high frequency（UHF）electromagnetic waves ranging from several hundreds of MHz to several GHz in GIS.In this paper

the finite difference time domain method is used to simulate the relationship between PD waveform and PD-induced UHF electromagnetic wave in GIS.Firstly

the relationship between PD magnitude and the peak to peak（p-p）value of PD-induced electromagnetic wave is evaluated

and the simulation results show that p-p value of PD-induced electromagnetic wave is not sensitive to the variation of PD magnitude.Secondly

the relationship between PD current change rate and p-p value of PD- induced electromagnetic wave is studied

and the simulation results show that the two factors are about correlated linearly. Finally

the relationship between PD current change rate and the proportion of higher order modes in the PD induced electromagnetic wave is investigated using the coefficient of variation

and the simulation results show that the proportion of higher order modes increases when the change rate of PD current increases.