Molecular dynamics simulation for gassing of XLPE degradation
Cross-linked polyethylene(XLPE)cables are crucial components in urban power distribution networks,and a profound understanding of XLPE insulation material degradation mechanisms is fundamental for proposing effective fault assess-ment and diagnostic methods.In recent years,the concept of using gas products for cable condition diagnosis has gained significant attention,however,existing research has yet to thoroughly elucidate the gas generation pathways and mechanisms affecting XLPE insulation.Therefore,based on molecular dynamics simulation methods,the degradation and gas generation mechanisms of XLPE from the atomic and radical levels were revealed.Initially,an initial geometric model of polyethylene molecules was constructed based on the Monte Carlo method.An algorithm for cross-linking of polyethylene based on the distance probability criterion was used for establishing a molecular dynamics geometric model of XLPE with high chemical rationality and physical significance.Subsequently,molecular dynamics calculations based on the ReaxFF reactive force field were employed,and a radical chain reaction pathway for characteristic gas product generation during XLPE degradation was established through particle tracking.The results indicate that the radical chain reaction leading to hydrogen generation involves two reversible steps.Radical chain reactions for hydrocarbon gas molecules and carbon oxide molecules originate from the breakage of C—C bonds in XLPE molecule chains for yielding methyl end groups,with the specific types of generated products determined by the concentrations of oxygen and hydrogen radicals.This study provides a reference for understanding gas generation phenomena in XLPE cable systems,and revealing the deterioration and gas generation mechanisms of XLPE solid dielectrics at the atomic level.
molecular dynamics simulationcross-linked polyethylenegassingfree radical reactionReaxFF force field
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