Diffusion Behavior of Formic Acid in a Transformer Insulation System with Modified Natural Ester Oil

During the prolonged stable operation of transformers, insulating oil paper will be affected by acid. Studying the diffusion of acids is crucial as they can speed up the aging of the insulating materials. Natural ester oil, emerging as an alternative to traditional mineral oil, can improve its performance advantages by adding nanoparticles significantly. This study utilized molecular dynamics simulations to explore the diffusion behavior of formic acid in a transformer insulation system with modified natural ester oil. The results showed that the mean square displacement of formic acid was 66.41 Å<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in the nano-modified oil-paper layer model, which was 47.19 Å<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> less than that in pure oil-paper layer model. Furthermore, the concentration of formic acid distributed at oil paper interface is relatively low, and its interaction energy with insulating oil is greater. This effectively inhibited the movement of formic acid, mitigating the degradation of transformer paper caused by formic acid. The nanoparticles’ adsorption of formic acid enhanced the insulation performance and anti-aging properties of transformers, thereby prolonging the use of insulating oil and improving the overall anti-aging performance of the transformer.