Analysis on Equivalence Between UHF Discharge Signals Caused by Voltage Pulses Artificially Injected Into GIS and That Caused by Actual Partial Discharge Signals Inside GIS
LI Duanjia · Power System Technology · 2014
It is the key procedure for on-site calibration of the sensitivity of(ultra-high-frequency) UHF test system by artificially injecting the voltage pulse into GIS, which is equivalent to the partial discharge(PD) inside the GIS. The distribution differences of time-domain amplitudes and frequency spectrum of UHF signals caused by artificial voltage pulse and actual PD inside the GIS are researched by experiments. A PD testing platform based on 220 kV GIS equipments is constructed and inside the cavity near the outgoing line the UHV electromagnetic waves caused by artificial voltage pulses and PD defects are transmitted respectively and the UHF signals are received by four disc antennae fixed on typical positions. The amplitudes of UHF signals at different positions are measured and the attenuation degrees of UHF signals caused by artificial voltage pulses and PD signals are contrasted. Applying Fourier transform to signal waves, the frequency spectrum distributions of the two kinds of UHF signals are contrasted. Research results show that the UHF signal caused by artificial voltage pulse and passed through the circuit breaker is attenuated a little bit more than the UHF signals caused by PD; the frequency spectrum distribution of the UHF signal caused by artificial voltage pulse is close to that of the UHF signal caused by PD, besides, the rising time of the voltage waveform of artificial voltage pulse varies within the range from 0.3ns to 1ns and it does not influence the frequency spectrum distribution of UHF electromagnetic wave. The obtained research results are available for reference to the on-site calibration of sensitivity of UHF test system.