Han, Shuai

Huang, Xuwei

Li, Qingmin

Liu, Tao

Lu, Xu

Lu, Yangfei

Wang, Zhongdong

Partial discharge (PD) is one of the most important causes of insulation aging and failure in high frequency power transformers. In order to accurately evaluate the influences of frequency and temperature on PD characteristics of polyimide films under high frequency sinusoidal waveform, a PD test system with variable frequency and temperature was established. The phase spectrum, repetition rate and amplitude of PD pulses along with insulation life were investigated at different frequencies (0.5~40 kHz) and temperatures (30~200℃). Experiment results indicate that with the rising of frequency, the average number and amplitude of PD pulses in a cycle increase first and decrease afterwards, showing an inflection point in the variation curves, and the inflection point will move gradually toward the low frequency direction when the temperature is higher; while the discharge number and amplitude increase monotonically with temperature rise. Based on the correlation between spaces charges and characteristic parameters of PD pulses, influence mechanism of temperature on PD properties, combined with frequency-induced thermal effect and the impact of frequency on space charge dissipation process, the mathematical model and formation mechanism of inflection point phenomenon are presented in this paper, which presents theoretical reference for elucidating the partial discharge mechanism under high frequency stresses.</p

Frequency-Induced Inflection Point Phenomenon and Formation Mechanism of Partial Discharge With Polyimide Films

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