Decomposition Characteristics of SF6/N2 Under Partial Discharge of Different Degrees

Abstract

SF6/N2 gas mixture can not only reduce the consumption of SF6 in power system, but also effectively alleviate SF6 greenhouse effect. Since SF6/N2 can decompose under the alternating current partial discharge(PD), its decomposition characteristics are closely related to PD attributes. Therefore, the fault diagnosis method can be established through its PD decomposition characteristics. However, at present, the decomposition characteristics of SF6/N2 mixed gas under PD have not been fully grasped, and the correlation characteristics between decomposition characteristics and PD intensity have not been obtained. To this end, this paper uses pin-plate electrodes to simulate the typical metal protrusion insulation defects in GIS equipment. SF6/N2 decomposition experiments are conducted at different PD intensity to study the correlation between the PD decomposition characteristics of SF6/N2 mixed gas and PD intensity. The results show that: the generation rate of characteristic decomposition components such as SOF2, SO2, SO2F2, SOF4, CF4, CO2, NO, NO2, and NF3 are positively correlated with PD intensity; NO2 and (SO2F2+SOF2+SOF4+SO2) can be used as the characteristic quantity to judge the whole process of PD, SO2F2 can be used as the feature to judge the early PD, and SOF2 and SOF4 can be used as the features to judge the severe PD. The results of this paper will lay the foundation for the monitoring of equipment insulation status using SF6/N2 decomposition characteristics in the future.