Research on the Distinction Method of Partial Discharge Inside and Outside the Windings of 110 kV Transformer in Early Operation

This paper presents a method to distinguish partial discharge inside and outside transformer windings using online dissolved gas analysis and acetylene concentration measurement in 110 kV oil-immersed self-cooled transformers during early operation. A finite element model of the transformer is built, and four typical locations prone to partial discharge are selected to simulate acetylene diffusion. Results show that when partial discharge occurs within windings, the time for acetylene concentration to reach the alarm value increases from top to bottom detection points. However, no clear pattern is observed for discharges outside the windings. Acetylene concentration peaks, steady-state values, and differences increase as detection points get closer.