Impact of harmonics on needle-plane partial discharge in oil-paper insulation

Typically, electrical breakdown and electrical aging of power transformer are initiated by partial discharge. There are plenty of factors that influence partial discharge, one significant factor is harmonics issue. In this paper, harmonics impact on partial discharge behavior under HVAC is studied, which uses needle-plane as the electrode configuration because of its widely existing within power transformer. Oil-paper insulation is the test object in this research to observe for PD activity such as PD inception voltage and phase-resolve PD. This research aim is not only focuses on several specific impacts of harmonic source on partial discharge, but also wants to demonstrate the significance of harmonics awareness. Nowadays, there are so many high voltage equipment that are working under harmonic component, it is risky enough to face against an unexpected danger under working operation. The experiment of this research focuses on HVAC superimposed with various composition harmonic component, which means that the order and percent THD (Total Harmonic Distortion) are discussed. The selected THD is designed to be able to observe for the differences clearly. Harmonic order from 3
^rd
, 5
^th
, 7
^th
, 9
^th
and 11
^th
is applied, which is the main component that is generated by the power electronics. Phase shift of injecting harmonic component is designed up to 270-degree angle. Meanwhile, in order to get the partial discharge characteristics under different magnitude of harmonics, the percent of each harmonic order is also changed, which can be calculated to find for THD.