Influence of Gas Flow on Partial Discharge Behaviors in Air and Nitrogen

Gas flow is an unavoidable factor to influence partial discharge (PD) behavior of insulators, e.g., in the cases of strong wind and high-speed train. In this paper, the surface charge distribution of PD sequences was obtained by the PD measurement system based on Pockels effect in different gas flows. Both phase-resolved PD (PRPD) and pulse sequence analysis method (
dV–dV
pattern) were employed to study the PDs behavior. We found that the air flow could homogenize the distribution of surface charge spots and influence the inception voltage, discharge number, as well as average discharge current. The discharge number increased with the airflow velocity until reaching its maximum at the threshold of 4 L/min. Although in nitrogen, with increasing the nitrogen flow velocity, the surface charge distribution became more uniform and the discharge number decreased together with its corresponding PDs pattern varying at the same time. This difference of PD behaviors in air and nitrogen was attributed to the presence of oxygen molecules in gas.