Critical study of partial discharge inception in voids: statistical behavior to stochastic nature

Abstract

Although many studies have been done and advanced progress has been made in understanding partial discharge (PD) behavior in the void, this is not the case firinception of PD, especially its stochastic nature. The statistical behaviors of PD inception voltage (PDIV) and inception time delay (PDTD) inside the void were investigated in this study through repeated tests to observe the stochastic nature of PD inception. The results show that the PDIV and PDTD of the void are highly dispersed and obey Weibull and exponential distributions, respectively. The significant dispersion of PDIV can be attributed to the statistical time delay of PD inception. The lengthy inception delay is attributable to a lack of free electrons. The exponential distribution of PDTD indicates that free-electron generation is completely random; further, the stochastic nature of void PD inception is determined by the supply of free electrons. The test method (voltage rise rate, test time, and test time interval), void parameters (size, material, and surface condition), and background radiation determine PD inception by affecting the volume ionization or surface-emission process providing free electrons. Enhanced background ionization or significant increase in test voltage and test time allow for the effective detection of void defects during PD tests. This work contributes to an empirical understanding of the physical process of PD inception in voids and improving existing PD testing technologies.

Distribution characteristics for initial time delay of streamer of shielding spheres under operating impulse voltage at high altitudes

“…The shape parameter b describes the shape of the Weibull Curve. If the shape parameter b increases from 0, the curve will gradually change from a right deflection curve to a left deflection curve [34]. If altitude is 50 m, the shape parameter b is 2.00, and the Weibull Curve is a right deflection curve; the statistical time delay obeys the special case of Rayleigh Distribution, which is consistent with the conclusion of literature [18] in low altitude areas.…”

“…Weibull Distribution Model is a distribution model proposed by Weibull. W based on the theory of 'weakest-link', it is used to calculate system failure probability distribution including several links, and it is applicable to failure of one link can stop the whole system [32][33][34]. In the discharge gap, any effective electron generated in critical volume can start the streamer, which meets the applicable conditions of Weibull Distribution Model.…”

“…In order to study the probability distribution characteristics of statistical time delay of streamer caused by altitude and electrode size, the Weibull Parameter fitting is conducted for experimental data of statistical time delay of spherical electrode (diameter of 1.3 m) at altitudes of 50 m and 2200 m, as well as the statistical time delay experimental data of spherical electrodes (diameters of 0.6 m and 1.6 m) at 2200 m altitude by According to figures 8, 9 and tables 5, 6, the scale parameter a and shape parameter b increase with an increase of altitude and electrode size at altitude. The scale parameter a defines the position of the Weibull curve relative to the threshold, and its value is 63.2% of the initial statistical time delay of streamer [34], that is, the statistical time delay of spherical electrode (diameter of 1.3 m) at 50 m altitude. The scale parameter of Weibull distribution is 3.05, which means the statistical time delay passes 30.5 µs under this discharge condition, and the initial probability is 63.2% for streamer.…”

Use of partial discharges measurements and video recordings to investigate the influence of relative humidity on zinc oxide subjected to high electric fields

“…It is well-known that repetitive PDs in insulating materials can result in long-term damages since the released energy can cause a rapid heating and ultimately dielectric breakdown [21][22][23][24]. Measurements of PDs are commonly used in electrical engineering to assess the degradation and aging of high-voltage insulators [25][26][27][28][29], but the method has not yet been broadly adopted for ceramic materials [30][31][32][33][34]. In the context of flash sintering, PD measurements were recently shown to be an efficient method to characterize the quality and number of the electrode/sample contact areas when no Pt paste was used to sinter Y-stabilised zirconia (YSZ) above 250 • C [35].…”

PD characteristics and deterioration mechanism of oil-impregnated pressboard with bubble defect

“…Secondly, regarding the study on the degradation characteristics of OIP/OIPB due to bubble PD, Zhang Rui et al [15], [16] studied the degradation characteristics of OIP due to the continuous action of bubble PD between OIP layers, and they concluded that the mechanisms of OIP failure due to PD include direct failure and cumulative damage failure. The choice of mechanism depends on the evolutionary stage of PD and the conditions of the oil-paper insulation.…”