| In recent years along with the development of national construction,accidents such as trip failures,line conductor damage and car crash often happens because of the tower crane,pump truck and other large machinery dash against overhead transmission line when they work near transmission line.The damages caused by large machinery and other kinds of external forces have become a great threat to the security and stability of overhead transmission lines,which can easily cause economic losses and social impact.Due to its long-term in the nature,overhead transmission lines have characteristics include wide distribution,long transmission distance,complex terrain conditions are greatly influenced by the environment that brings great difficult to the protection against external forces.So,it is urgent to study the effective monitoring technology and devices t.In view of the above problems,this paper will combine the basic requirements and practical experiences of overhead transmission line protection anti-external force damage to introduce the magnetic field measurement technology into external force damage monitoring field of overhead transmission lines.It aims to research the new technology and develop monitoring device to solve the problems.The main research contents are as follows.Firstly,the magnetic field distribution of 110 kV and 220 kV overhead transmission lines which have different number of circuis,tower types and wire apart forms are analyzed.Taking the influence factors including wire sag and field measured datas into account,the simulation and calculation model based on ANSYS was established and optimized,laying a theoretical foundation for the smooth progress of the project.Secondly,according to the simulation model of magnetic field intensity,the back-calculation technology of the distance between transmission line and large-scale construction machinery in normal load is studied.The mathematical model and software of distance back-calculation are also designed,which can obtain the real time distance by magnetic field intensity measurement.Thirdly,the paper put forward the on-line power supply technology suiting for the monitoring system of anti-external force damage for overhead transmission line.Through analysis of electromagnetic theory and technology's status,the feasibility of on-line power supply is demonstrated.According to the different functional requirements of each component of the monitoring device,the power supply mode combining online power extraction with lithium battery is proposed.Fourthly,the paper proposed the wireless communication technology under strong electromagnetic environment.Through the analysis of wireless radio frequency technology,wireless frequency hopping technology and wireless spread spectrum technology,we putforward to adopt wireless radio frequency as the main part of the monitoring system,supplemented by wireless frequency hopping and spread spectrum technology to ensure the reliability and real time of wireless communication.The communication protocol is studied and the scheme is made.Fifthly,the hardware of anti-external force damage monitoring device which mainly includes the current measurement devices,the magnetic field measurement devices,alarm devices,anti-jamming wireless communication module is designed to realize the functions of current measurement,invasive monitoring and layered warning.The monitoring technology of anti-external forces damage for overhead transmission line based on magnetic field measurement has unique advantages in efficiency,precision and coverage.It can only realize the full coverage of dangerous points in the construction sites but also greatly improves the monitoring accuracy by using magnetic field measurement technology.Besides,it and can effectively shield the surrounding environment from interference.Combined with the actual demand,it has a very broad market demand and huge market potential which will certainly produce enormous economic benefits. |
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