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Research On High Frequency Excited Melting Ice Technology For Ice-covered Transmission Lines

Posted on:2020-07-18Degree:MasterType:Thesis
Country:ChinaCandidate:T HuFull Text:PDF
GTID:2392330602960356Subject:Engineering
Abstract/Summary:PDF Full Text Request
Winter line ice coating will increase the probability of broken bar(tower)disconnection,insulator flashover,etc.and is one of the urgent problems to be solved.At present,mainstream de-icing measures at home and abroad include mechanical de-icing,natural de-icing,electric de-icing and pulse de-icing.But each method has its own limitations,and it is difficult to achieve a satisfactory balance between the economics and reliability of melting ice.To this end,this paper introduces a key technology based on high-frequency high-pressure melting ice,which can meet the economical,energy-saving and reliable melting ice under the condition of uninterrupted power supply.This article first introduces several common ice coating conditions and analyzes the characteristics and formation conditions of each ice coating.In view of the various advantages and disadvantages of the existing de-icing measures,the high-frequency high-pressure deicing technology introduced in this paper has the advantages of high efficiency,small current,good reliability,and can meet the requirements of non-power-off deicing.The main principle is to apply high-frequency high-voltage current in the line that needs to melt ice,so that the minimum heat generated along the line is not covered with ice,and the heat generation along the line is as uniform as possible.When the frequency is increased,the skin effect along the line is significantly enhanced,and more heat is generated under the unit resistance,and the ice melting current at this time will be greatly reduced.An increase in frequency will also increase the dielectric loss of the ice layer.In the case of high-frequency excitation melting ice technology,heat is directly generated in the ice layer,which greatly improves the energy utilization rate compared to the conventional heat transfer process.Based on the theory of uniform transmission line,this paper establishes the equivalent circuit and equivalent distribution parameter circuit model of the ice-covered transmission line.When the skin effect and the maximum value of the dielectric loss are as equal as possible,the optimal frequency and voltage deternination method for the additional power supply melting of the transmission line is given,and the voltage and frequency under the common dielectric loss angle are obtained.Excellent combination.Finally,taking the 110KV voltage level as an example,the influence of voltage and frequency on the thermal power,thermal power uniformity and power factor along the line is analyzed by MATLAB/Simulink simulation software.The research results show that the frequency and voltage of the additional ice-melting power supply play a decisive role in the ice-melting effect.The proposed optimal frequency and voltage determination method can achieve reliable and efficient ice-melting effect of the ice-covered wire.Finally,the design of the high-frequency high-pressure ice-melting power supply is designed.The topology of the power supply is composed of AC-DC-AC current-mode converters in cascade form.The carrier phase shift technique is used to reduce the switching frequency of the power electronic device and reduce the power loss.The capacity of the high-frequency power supply is reduced by connecting the adjustable capacitors in series in the ice-melting circuit to meet the reactive power requirements of the line.The research results play an important role in the promotion and application of high frequency ice melting technology.
Keywords/Search Tags:high frequency excitation melting ice, dielectric loss, skin effect, AC-DC-AC current mode converter, carrier phase shifting technology
PDF Full Text Request
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