Investigating the Impact of Floating Nonspherical Micro-Impurity on Transformer Oil Streamer Dynamics

The dielectric reliability of transformer oil is essential for the secure operation of high-voltage transformer in power systems. However, streamer discharge behavior can be significantly impacted by inservice contamination from micro-impurities, especially non-spherical particles like metal flakes, cellulose fibers, and aging by-products, which can cause premature insulation breakdown. This study uses a 2D axisymmetric model built in COMSOL Multiphysics to investigate how non-spherical micro-impurities affect streamer discharge behavior. Electrostatics, charge transport, and heat transfer have been used in the simulation to study the electric field distribution, space charge density, and steamer morphology in the presence of spherical and non-spherical particles. The results demonstrate that non-spherical particles, which act as secondary ionization centers and drive streamer branching, produce localized electric field enhancements due to their sharp edges and uneven surfaces. Spherical particles, on the other hand, exhibit slower and more consistent discharge behavior due to their finer field interactions. Sharp-edged impurities encourage greater space charge accumulation and electron concentrations, leading to hotspots that raise the risk of dielectric breakdown. This morphology-driven dynamic raises questions regarding the reliability of transformer insulation and significantly affects pre-breakdown procedures. This paper highlights the necessity of realistic impurity geometries in modelling for accurate investigations of streamer dynamics in liquid dielectrics. In order to increase grid reliability and asset longevity, the manufacturers may also utilize these findings to create robust insulating systems that are more resilient to particle-induced deterioration in power transformers.