Numerical Simulation Study on the Influence of Air Pressure on the Trichel Pulse Characteristics of Negative Corona Discharge in Needle-Plate Electrodes

To meet the demands of constructing new power systems, the scale of pumped storage generator units continues to expand, making the issue of corona discharge in stator bars under low-pressure conditions at high altitudes increasingly prominent. This paper employs a numerical simulation method to investigate the impact of air pressure on the negative corona discharge characteristics of needle-plate electrodes. Based on a fluid dynamics model, the plasma module of COMSOL Multiphysics software was utilized for solution. The model incorporates 10 primary particle species and 19 key chemical reactions. Under conditions including a needle-plate gap of 3 mm, temperature of 300 K, and applied voltage of −2.5 kV, the negative corona discharge process was simulated and calculated at pressures of 1.5 atm, 1 atm, and 0.8 atm. The Trichel pulse current waveforms, ionization reaction rates of N2, electric field strength, and spatial distribution characteristics of electron density under different pressures were obtained. The results demonstrate that as pressure decreases, the peak Trichel pulse current increases, ionization reaction rates rise, and both the electric field strength and electron density in the discharge region significantly increase. By correlating the evolutionary laws of electron impact ionization processes, electron density, electric field intensity distribution, and current pulse characteristics under varying pressure conditions, this study provides a theoretical basis for revealing the mechanism of air negative corona discharge in high-altitude and low-pressure environments.