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Study On High-frequency And High-voltage De-icing And Its Influencing Factors For Transmission Line

Posted on:2020-08-19Degree:MasterType:Thesis
Country:ChinaCandidate:X L YuanFull Text:PDF
GTID:2392330602468441Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
Transmission line icing pose a serious threat to the safe and stable operation of power system.At the beginning of 2008,the accidents such as flashover of insulators,conductor break and tower collapse caused by transmission line icing in southern China,which caused more than 100 billion losses in the national economy.The power grid ice disaster accidents are still frequent in recent years.Therefore,the ice-melting technology of transmission line has been paid attention.With the development of research,AC and DC short-circuit de-icing have been widely used,but they all have their own limitations.In this paper,a new de-icing method for transmission line is studied-high-frequency and high-voltage de-icing,which has the advantages of high ice-melting efficiency and uniform heating,and can achieve on line ice-melting for transmission lines.Firstly,The paper presents the principle of high-frequency and high-voltage de-icing-high-frequency skin effect and dielectric loss of ice,studies the dielectric properties of the ice.It is found that the polarization loss of pure ice is the highest at 10kHz frequency.And the icing of 110kV Weilao Line on Meihua Mountain,Bijie City,Guizhou Province,was taken as the sample for experimental measurement.It is found that the tangent value of dielectric loss angle of ice is 0.1.By using mathematical theory,the mathematical model of wire icing is derived,that is,the shape of ice coating can be divided into three parts:uniform circular icing,eccentric circular icing and eccentric ellipse icing.It establishs the physical and mathematical models of transmission line icing.The expressions of de-icing frequency and voltage are derived by using uniform transmission line theory,and the de-icing requency and voltage are obtained by simulation under different ice loss angles.What is more.,the heat production and heat loss in the process of conductor de-icing are studied according to the monitoring of icing in Guizhou area.The results show that convection heat transfer is the main factor affecting melting ice and the influence rules of local convection heat transfer on de-icing of transmission line.That is to say.The leeward side of the ice-covered conductor first melts and then the windward side melts in the process of de-icing.At last,a coupling field model of electromagnetic and thermal is established,and the high frequency de-icing time and influencing factors(ice thickness,ambient temperature,wind speed)are simulated by finite element software ANSYS.The results show that:The de-icing time increases with the increase of ice thickness,and there is an approximate linear relationship between the them.The ambient temperature has a great influence on the de-icing time of high-frequency and high-voltage,and the de-icing time increases with the decrease of ambient temperature.The influence of wind speed on high-frequency and high-voltage de-icing is also obvious,and the de-icing time is longer with the increase of wind speed.In this paper,the calculation method of de-icing high-frequency and high-voltage is deduced.and on the basis of the simulation results,the influence of local convection heat transfer on ice melting and the influence of different external factors on ice melting time are revealed,which further complement the theory of de-icing high-frequency and high-voltage and provide a theoretical and technical basis for the practical application of high-frequency and high-voltage de-icing.
Keywords/Search Tags:high-frequency and high-voltage de-icing, de-icing frequency and voltage, Windward and leeward, Electromagnetic-thermal coupling field, de-icing influencing factor
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