Study On Corrosion Rate Calculation And Life Prediction Of Grounding Electrode

Electric energy is the main energy in modern society.The safe and stable operation of power system plays an important role in the development of national economy and social stability.Grounding device is a key component of power system.Good grounding is an important guarantee for the safe operation of power system.Corrosion is the main factor affecting the safe operation of grounding system.When the grounding conductor is corroded,its current capacity decreases and its diversion effect decreases.When lightning strikes or short circuit occurs,it will threaten the personal safety of the staff,the safety of equipment and the stable operation of the system,and the consequences are incalculable.When grounding conductor is seriously corroded,it may even break and lose grounding function.Therefore,in order to ensure the safe and stable operation of power system,it is of great significance to study the corrosion of grounding conductor.Firstly,the characteristics of service environment and corrosion development process of grounding conductor are analyzed,and the corrosion mechanism and micro-reaction principle of grounding conductor are clarified.The electrochemical polarization curves of typical grounding materials were tested by electrochemical polarization curve test method.After fitting the test data,the electrode reaction parameters of grounding materials in soil simulation solution were obtained.Based on the reaction kinetics principle,a simulation model of grounding conductor corrosion is established.The electrode reaction parameters of grounding material obtained by polarization curve test and fitting are used to simulate the corrosion rate of grounding conductor in soil simulation solution.The corrosion rate obtained by simulation is compared with that obtained by polarization curve fitting.It shows that the simulation results of grounding conductor corrosion in soil simulation fluid are accurate,which proves the validity of the simulation method and model.Taking the carbon steel grounding conductor as the research object,considering the grounding current and material migration in the soil,the corrosion simulation model of the grounding conductor in the soil was established,and the corrosion rate of the grounding conductor was simulated by using the electrode reaction parameters of the carbon steel sample obtained from the test.Through simulation calculation and analysis,the corrosion characteristics of grounding conductor under grounding current are studied,and the correctness of the model is verified by typical electrolytic corrosion test.The mechanism of the influence of soil physical and chemical properties on the corrosion of grounding conductor is analyzed,and the law and weight of the influence of soil factors on grounding conductor are obtained.Based on factor analysis method,a formula for calculating the natural corrosion rate of grounding conductor is proposed.The results are compared with the evaluation results of soil corrosion factor index and the actual corrosion data.The results show that the proposed corrosion rate considering the weight of corrosion influence factor.The rate calculation formula is more consistent with the actual corrosion results.Based on the natural corrosion rate and electrolytic corrosion rate of grounding conductor calculated by simulation,the prediction method of grounding conductor corrosion life and the calculation formula of residual life are put forward under the premise of ensuring the thermal stability and effective diameter of grounding conductor to meet the operation requirements.The concrete calculation case of cumulative corrosion depth prediction model is completed,and the residual life of grounding conductor is obtained.Based on pitting theory,the monitoring method of accumulative corrosion depth is studied,and a monitoring device for accumulative corrosion depth is designed and developed.The feasibility of the device is verified by accelerated corrosion simulation experiment,and a pilot application is carried out,which provides a simple and effective tool for the operation and maintenance of grounding conductor.