Research on the Aging Mechanism of Insulating Paper in UHV Converter Transformer Valve Side Outgoing Line Devices

In response to the problem of performance degradation of the insulation paper in the high voltage direct current (HVDC) converter transformer side outgoing line device due to aging under high temperature, electric fields, and other multi-field coupling, a research framework integrating molecular dynamics simulation is proposed. First, a cellulose molecular model is constructed, and the aging process under different temperatures and electric field strengths is simulated using the ReaxFF force field, analyzing the system’ s energy, chemical bond breakage, and changes in dielectric constant. Experimental results indicate that as the temperature increases, all energy forms of cellulose continuously rise, with kinetic energy surpassing non-bonded energy at 600K, resulting in structural damage; the mean square displacement (MSD) also continuously increases with temperature, indicating intensified chain movement; the dielectric constant steadily rises, with enhanced polarization; the electric field causes bond lengths to elongate, promoting glycosidic bond breakage. Moreover, pyrolysis analysis shows that the main products are water molecules, ethanal, formic acid, 1,2-dihydroxyethylene, and carbon dioxide, with the number of products increasing over time, dominated by ethanal. The core mechanism of pyrolysis involves chain opening and glycosidic bond breakage, revealing the aging process under multi-field coupling. This framework elucidates the aging mechanism at the microscopic atomic level, providing a theoretical basis for fault diagnosis and insulation optimization.