To improve the accuracy of degradation modeling for distribution network lines

this paper proposes a multi time scale degradation analysis method.Considering the heterogeneous mechanisms of long term natural degradation and short term sudden impact degradation

refined models are established for towers and conductors separately.In the long term model

tower degradation is quantified by the cross sectional loss of reinforcement steel caused by corrosion

dynamically characterized through chloride ion diffusion and active corrosion stages.Conductor degradation integrates both micro vibration wear and high temperature thermal aging

quantified using time varying degradation functions and thermal equilibrium equations.In the short term model

a mapping relationship between wind induced impacts and degradation increment is introduced to characterize irreversible damage accumulation.By linearly superimposing long term and short term degradation components

a full process degradation model and failure probability assessment method are proposed.Simulation results demonstrate that under combined long and short term degradation

the degradation levels of towers and conductors reach 16.54% and 22.67%

respectively

with the failure probability 19.5% higher than that of the long term only model

verifying the necessity of the proposed synergistic model under wind conditions.This study provides theoretical support for reliability assessment and risk prevention of distribution networks.Keywords:distribution network lines;strength degradation;multi time scale;long term degradation;short term impact