Investigation of Humid Air on Corona Onset Voltage in Wire-Plane Electrodes Under AC–DC Composite Voltages via Test and Modeling

Abstract

Detailed characteristics of corona onset voltage under AC-DC composite voltages in wire-to-plane electrodes at various humidity were investigated both experimentally and numerically in this paper. The humidity experiments under AC-DC composite voltages were carried out in the artificial climate chamber. The experimental results indicate that both the corona onset voltage and corona onset electric field strength of positive DC-AC and negative DC-AC decreased with the increase of humidity under composite voltages. Meanwhile, a fluid-hydrodynamic corona model considering humidity and photoionization was established to investigate the influence of humidity on space charge distribution. The numerical results state clearly that compared with the corona under single voltage, the corona under composite voltages was more intense and generated more space charges. Secondly, the higher the humidity was, the higher the concentration of positive ions, electrons and negative ions would be. Finally, the increase of humidity promotes the increase of net ionization coefficient, photoionization rate and net electron generation rate. Under the same humidity and AC voltage, the photoionization rate and net electron generation rate of negative DC-AC was faster than positive DC-AC.