Numerical Analysis for Long-Term Negative Discharges in Air with Needle-Plane Electrode Configuration

In this study, we investigate the partial discharge mechanism in needle electrodes under direct current (DC) voltage, with a focus on streamer propagation in atmospheric pressure air. Initially, we validated our numerical model by measuring current density at the ground electrode using a high-frequency current transformer (HFCT) and ultra-high frequency (UHF) sensor. In the extended study, we will compare the analysis results for different gaps between the needle electrode and the ground (5, 8, and 10 mm), adjusting the applied voltage from the partial discharge inception voltage to 1.1, 1.2, and 1.3 times the voltage level. We simultaneously conducted experimental and numerical analyses of the discharge current characteristics, focusing on five key parameters: rise time, decay time, maximum amplitude, pulse width, and pulse interval. Additionally, we investigated the long-term behavior of corona discharge using pulse sequence analysis (PSA) diagrams, aiming to apply these findings in real-world electrical equipment under operational conditions.