Numerical analysis of temperature characterization of air gap discharge in solid insulation under power frequency voltage

Air gap defects in solid insulation of power equipment can cause partial discharge. Temperature, as an important characterization of partial discharge, can be used as a criterion for the deterioration degree of air gap defects to some extent. In this paper, the temperature characterization of air gap discharge is studied. A plasma-kinetics-based dielectric barrier discharge model is constructed. The calculation method of air gap discharge heat source under power frequency voltage is presented. Moreover, the influence of voltage amplitude and gap thickness on temperature is studied. Obtained results indicate that under the power frequency voltage, Joule (Ohmic) heat contributes 90% to the heat source, and O-4(+) and O-2(+) and electron e are the main contributors to Joule (Ohmic) heat. O-4(+) is also the dominant ion in the mixed gas. As the discharge progressed, O-4(+) almost all clustered near the instantaneous cathode. The O-2(+) density generally depends on the electron density, but compared with the electron, the spatial distribution of O-2(+) density is slightly shifted to the instantaneous cathode. The discharge heat source is positively correlated with the air gap thickness and the voltage amplitude. With the increase in air gap thickness, the rising rate of heat sources will also increase. However, when the voltage is 10 kV, the heat source increases first and then decreases with the increase in the air gap thickness. The discharge does not occur when the air gap thickness reaches above 4 mm. This study provides theoretical support for identifying the deterioration degree of air gap defects from the view of temperature. Published under an exclusive license by AIP Publishing.