Research On Damage Mechanism And Preventive Measure For Ground Wire-Suspension Clamp System Under Power Frequency Short-Circuit Current

Under the action of power frequency short-circuit current,the ground wire-suspension clamp system may cause damage or even breakage of the ground wire due to overheating of the contact area.However,the investigation of this type of injury has not been paid much attention.The breakage of the ground wire will pose a threat to the safe and stable operation of the power grid.Therefore,it is necessary to study the rupture mechanism and preventive measure of the ground wire-suspension clamp system under the action of power frequency short-circuit current.The research work of this paper mainly includes the following four aspects:(1)Taking the ground wire-suspension clamp system as the experimental object,the experimental research of the ground wire-suspension clamp system under different operating conditions is carried out,including the short-circuit impulse current experiment and the transient temperature rise experiment based on small current.The actual operating conditions of the power frequency short-circuit current flowing through the ground wire-suspension clamp system are reproduced through experimental research,and the internal temperature rise characteristics of the ground wire-suspension clamp system are analyzed.(2)Based on the electromagnetic-thermal-structural multi-field coupling,a three-dimensional simulation calculation model of the ground wire-suspension clamp system is constructed,and an improved contact bridge model is proposed to accurately simulate the contact shape of the contact point.The transient thermal effects and mechanical characteristics of the ground wire-suspension clamp system under the action of short-circuit current are analyzed by simulation calculation,and the numerical influence of the contact shape of the contact bridge and thermal stress on the simulation calculation results is analyzed.(3)Taking the effective surface density of micro-defects(i.e.the damage degree D)as the damage variable,the damage evolution model of ground wire in the ground wire-suspension clamp system is constructed through theoretical derivation.Based on the damage evolution model of ground wire,the damage of ground wire under the action of different short-circuit currents is analyzed.At the same time,combined with the results of experimental exploration and simulation calculations,the damage mechanism of the ground wire-suspension clamp system under the action of short-circuit current is summarized.(4)Based on the damage mechanism,it is proposed to wind the armor rod on the ground wire at the suspension clamp as an improvement measure.Combining finite element simulation methods and experimental methods to verify the effectiveness of the improved measure.The transient thermal effects,mechanical characteristics and experimental results of the two ground wire-suspension clamp systems under the action of power frequency short-circuit current are compared and analyzed,and the damage prevention mechanism of the improvement measure is summarized.