Characterizing the behavior of current pulses in corona discharge

Corona discharge is an unavoidable phenomenon in gas-insulated power equipment that can lead to the degradation of insulation systems. Much of the research on corona discharge overlooks the characteristics of the pulse stage, a complex region where large-amplitude current pulses occur. To better understand the factors that influence corona discharge, He et al. characterized the transition into the pulse stage and its properties in SF₆/N₂ gas.

“The degradation of inner insulation of gas-insulated power equipment will seriously affect the insulation performance of the equipment, may cause damage to the equipment, and affect the safe and stable operation of the power system,” said author Yanliang He.

To study this process, the authors observed the corona discharge from an electrode under an applied voltage situated within a gas-filled chamber. They found the onset of the pulse stage depends on a number of factors, including the applied voltage, the gas pressure and the density of positive ions present in the gas. During the pulse stage, small-amplitude current pulses occur more frequently and are joined by large-amplitude pulses, with the repetition rates of both pulses determined by the mean current and N₂ concentration, among other factors. Eventually, as the applied voltage continues to increase, the system enters the breakdown stage.

While the group paid attention to the impacts of N₂ concentration on the onset and behavior of the pulse stage in this work, their future focus will be to better understand how the gas mixture ratio affects the microscopic characteristics of charged particles during corona discharge.

Source: “Experimental study on pulse characteristics of negative corona discharge in SF₆/N₂ gas mixtures under DC voltages,” by Yanliang He, Anbang Sun, Jianyi Xue, Zhiwei Shen, Xing Zhang, and Guanjun Zhang, AIP Advances (2020). The article can be accessed at https://doi.org/10.1063/5.0002811 .