Partial Discharge Signal Analysis of Needle-Plane Electrode in Air Based on PRPD and Pulse Sequence Analysis

Corona discharge, a typical form of partial discharge (PD), is one of the primary causes of insulation failure in electrical equipment. Additionally, corona discharge has extensive applications in fields such as environmental protection, healthcare, and materials science. Therefore, studying the characteristics of corona discharge is essential. In this paper, a needle-plane electrode is used as a representative model to simulate corona discharge, and the corona discharge signals in air under power frequency AC voltage were measured. The phase-revolved partial discharge (PRPD) patterns, dV plots, and voltage differences frequency diagrams at various voltages were analyzed and compared by the combined analysis method of PRPD pattern and pulse sequence analysis (PSA). The study found that during the negative half-cycle, the initial discharge exhibits a large discharge magnitude, which is proportional to the instantaneous voltage. At higher voltages, the discharge transitions from Trichel discharge to a new discharge form, resulting in a decrease in discharge amplitude, with the PRPD patterns changing from the "line-type" to the "U-type". Due to the influence of space charge, the voltage difference will decrease with the increase of instantaneous voltage in open air gap.