Emission Spectrum Analysis of Two Typical Partial Discharge Forms Under High Frequency Square Wave Voltages

Although the increase in frequency improves the transmission efficiency of high-frequency transformer, a higher probability of insulation failure is caused by high-frequency partial discharges. Through a high-frequency experimental platform, emission spectrum tests on two types of insulation faults were carried out under high-frequency square wave voltages. Subsequently, the influence of frequency and voltage amplitude on the light intensity and the number of photons of emission spectrum caused by air corona were studied. Finally, the variation of the spectrum of the partial discharge occurring at the interface of gas-solid insulation with frequency was analyzed. The results show that, the characteristic spectrum of air corona is composed of the near-ultraviolet spectrum, which is caused by the energy level transition of N-2 molecules, and the number of photons of air corona is positively correlated with voltage amplitude and frequency. Partial discharges at the gas-solid insulation interface have band spectrums in the visible light region and the near-infrared light region except for the near-ultraviolet spectrum due to the energy level transitions of outer layer electronics and the vibrations of C-H chemical bonds of PET molecules. This paper preliminarily verified the feasibility of applying the emission spectrum diagnostic method to two typical partial faults under high-frequency square wave voltages.