Abstract
Partial discharge (PD) detection is essential to the operation of high-voltage systems. In this context, we investigate the basic characteristics of light emission during PDs in SF6 gas from the perspective of insulation diagnosis. A synchronous system is constructed using three optical photoelectric instruments with separate wavelength responses in the ultraviolet (UV, 189–352 nm), visible (VIS, 381–675 nm), and near-infrared (NIR, 737–920 nm) spectral ranges and a wide-band PD current pulse detector with a response of 1 pC. The results indicate that light emission depends upon the type of insulation defect and discharge energy. An increase in PD charge gives rise to more components in the spectral range from UV to VIS, and the presence of an insulator surface in discharges yields a more complex VIS-to-NIR spectrum. The phase-resolved partial discharge pattern (PRPD) of UV light pulses can reasonably reflect the electroluminescence process in the presence of the insulator surface and weak corona at negative voltage points. The PRPD of VIS light describes the features of the actual PD pattern in most cases. In comparison with the other two spectral ranges, light intensity in the VIS range is more sensitive to changes in gas-pressure-normalized voltage (Vrms/p). The linear fitting analysis of the relationships between the light intensity and PD charge shows that UV light detection has a greater sensitivity to the PD charge and that UV detection exhibits a greater degree of linearity. NIR detection is applicable only to severe PDs. We believe that our findings can significantly aid in application of optical PD diagnosis in SF6 gas insulated systems.
Highlights
Electrical discharges occurring in dielectrics are always accompanied by light emission, which allows us to determine the morphologies of the discharges and even examine the mechanisms underlying the various types of discharges [1,2,3]
Thethe spectrum varies within the applied electric field, and itspectrum is influenced by the lying along discharge path changes in the discharge energy driving different discharge types, which are determined by the presence of the insulator surface
The resulting optical spectrum depends on the variations in the UV, VIS, and NIR spectra are discussed based on the Partial discharge (PD) current measurement
Summary
Electrical discharges occurring in dielectrics are always accompanied by light emission, which allows us to determine the morphologies of the discharges and even examine the mechanisms underlying the various types of discharges [1,2,3]. With regard to enclosed-type high-voltage equipment, the reliability of the dielectric insulation inside is severely degraded in the presence of continuous PDs activity. With evolution in optical technologies, optical PD detection can be used as an ancillary means in laboratory studies and renders its considerable potential in PD diagnosis of actual power equipment such as gas-insulated switchgear/transmission lines (GIS/GILs). Micro-optical sensors and fluorescence fibers that can be installed inside equipment have shown great application potential in this regard [12,13]. The presence of trace amounts of impurities, such as air and nitrogen, and and nitrogen, and the structural nature of the electrode can yield more complex spectra [16,17].
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