Research On Corrosion Behavior And Corrosion Extent Evaluation Method Of Overhead Ground Wire In Power System

Overhead ground wires play an important role in ensuring the normal operation of transmission tower equipment and transmission wires,but their long-term corrosion problems caused by acid rain and acid deposits are particularly prominent.Therefore,the corrosion behavior of overhead ground wires and the quantitative evaluation method of corrosion degree are studied.It has important engineering significance for ensuring the safe and stable operation of the power system.In this thesis,hot-dip galvanized overhead ground wires are used as research samples,and different corrosion levels are formed through salt spray experiments.The corrosion behavior of overhead ground wires in three different electrolyte systems of 3.5%NaCl,saturated Na₂SO₄ and phosphate is studied,revealing the overhead ground wires.Correspondence between different corrosion degrees of ground wires and electrochemical parameters,study the corrosion behavior of new overhead ground wires under different electrolyte systems under stress,and explore the evaluation methods of different corrosion degrees of overhead ground wires.The main research contents are as follows:（1）Overhead ground wires with different corrosion levels were formed through salt spray experiments,and different corrosion products and surface characteristics were analyzed and studied.The results showed that there were corrosion pits several microns in diameter on the surface of lightly corroded overhead ground wires,and the corrosion products were mainly Zn and Zn O.Large areas of white surface appeared on the surface of moderately corroded overhead ground wires.Rust,the corrosion products are mainly Zn O and NaCl,the heavily corroded surface is rust flocs,which is brittle and easy to fall off.The corrosion products are mainly Fe₂O₃ and Zn Fe₂O₄.（2）The influence of scanning speed,temperature,stress and corrosion degree on the corrosion behavior of overhead ground wires was explored in 3.5%NaCl solution.The results showed that:the best scanning speed is 10m V/s;under the influence of temperature,as the temperature increases to 50℃The corrosion current density is increased to 2 times of 30℃,the charge transfer resistance is reduced to 5%of 25℃,and the corrosion rate is accelerated;under the influence of stress,when the stress is80MPa,the corrosion current density of the overhead ground wire increases to that of the unstressed state 16 times;the deepening of the corrosion degree will cause the corrosion potential of the overhead ground wire under the system to shift positively.（3）The influence of p H value,stress factors and corrosion degree on the corrosion behavior of overhead ground wires was explored in saturated Na₂SO₄ solution.The results showed that:under the influence of p H value,the corrosion current density at p H3.0 was about twice that at 6.0,polarization The resistance is reduced to 1/2;the radius of the Nyquist curve,the charge transfer resistance Rct,and the electric double layer capacitance Cdl decrease as the p H value decreases;the stress action can promote the corrosion of the overhead ground wire,increase its corrosion current density,and reduce it Polarization resistance.（4）The 4×PBS solution with ion conductivity of about 55.55 m S·cm^-1 was selected as the electrolyte system in the PBS solution,and the influence of different corrosion degrees and stress factors on the corrosion behavior of overhead ground wires was explored.The results showed that the corrosion degree increased,Tafel curve The self-corrosion potential shifts positively,and there is an order of magnitude difference;under the influence of stress,when the stress is 80MPa,the current corrosion density is2.22 times that under no stress,and the polarization resistance is reduced to 1/3,indicating that the solution is corroding the overhead ground wire The degree of detection has better adaptability.（5）The electrochemical test ship-shaped device that fits the special structure of the overhead ground wire was built,and the green non-polluting 4×PBS solution was used as the electrolyte solution,and the area of the electrochemical parameters of the corrosion degree was divided.The state of slight corrosion:<-0.72V;moderate corrosion State:-0.72V to-0.6V;severely corroded state:>-0.6V.Perform verification tests on the system conditions and potential regions,showing good adaptability.