Research On High Frequency De-icing Model For The Transmission Lines And Influencing Factors Of Temperature Field

De-icing and disaster prevention in power systems is a worldwide problem.In order to deal with the possible hazards of ice disasters to the power system,scholars at home and abroad have carried out a lot of research.At present,the power grid mainly uses DC and power frequency AC de-icing methods in de-icing projects,but there are limitations such as large de-icing current,line outages,and long de-icing time.High-frequency de-icing technology has high melting efficiency,uniform heat generation,and the possibility of online de-icing.In recent years,its research progress has attracted much attention.Based on the actual conditions of wire de-icing,the paper establishes an elliptical de-icing analysis model in the process of high-frequency excitation of ice-coated lines,the changes of temperature field and its influencing factors under uniform convective heat transfer and uneven convective heat transfer are studied.This research provides a technical basis for the engineering application of high-frequency de-icing.The thesis first focuses on the basics of high-frequency excitation de-icing technology such as ice-coating dielectric loss,dielectric characteristics,and skin effect.,and establishes the ice-coated line distribution parameter model,and analyzes the external high-frequency excitation source using transmission line theory.The influence of frequency and voltage on the effect of de-icing,using Matlab simulation to verify the feasibility of the parameters of the excitation source for de-icing.Then combined with the principle of heat balance of line melting under high frequency and calculated the de-icing parameters.Based on the principle of finite element analysis(ANSYS),the mathematical model of electromagnetic field and temperature field during de-icing of ice-coated wire and the finite element analysis model of electromagnetic-thermal coupling were established.Compared and analyzed the de-icing effect under the two calculation models of the cylindrical uniform de-icing static model and the elliptical de-icing model,the changes of convective heat transfer coefficient,de-icing critical current and de-icing time under different wind speed,ambient temperature and ice thickness are analyzed and obtained.Finally,based on the high-frequency de-icing electromagnetic-thermal coupling analysis method,the finite element software ANSYS is used to analyze the temperature field distribution of de-icing under uniform convection conditions and uneven convection conditions,and the changes rules of temperature field when wind speed,ambient temperature and ice thickness change are obtained.The simulation results show that during the de-icing process,under uniform convective heat transfer conditions,the convective heat transfer intensity affects the temperature rise rate of the inner surface of the ice layer.The wind speed decreases,the ambient temperature rises,the convective heat transfer intensity weakens,and the temperature rise rate increases.But the temperature rise rate decreases with the increase of ice thickness.Under the condition of uneven convective heat transfer,the temperature on the leeward side of the ice-coated conductor rises faster than that on the windward side.Compared with the condition of uniform convective heat transfer,the required de-icing time is reduced,and the temperature of the outer surface of the ice layer on the leeward side is higher The outer surface temperature on the windward side.The elliptical de-icing research model established in the thesis makes the de-icing analysis closer to the actual de-icing process.The res earched de-icing time,temperature field change rules and influence factors have an important reference for engineering applications.