Research Of Overhead Contact System Anti-icing Based On Online Monitoring

Overhead contact system is an important part of electric railway.It is exposed to harsh environment all the year round.In winter,icing of overhead contact system is a natural disaster that often occurs in tractive power supply system.When overhead contact system is covered by ice,the train can't receive current normally,causing the train can't operate normally,and also causing arc discharge between the contact wire and pantograph that will accelerate wiring aging.Seriously,galloping of overhead contact system is very fast and has large amplitude,and the vertical load and horizontal load of the wire both increase,that can lead to conductor strand broken and the collapse of pole and tower.After the severe ice disaster in 2008,domestic and foreign scholars did research on the icing problem of overhead line in electric power system and put forward de-icing methods such as manual de-icing method,chemical method and current heat ice-melting method.However,at present the manual de-icing method is usually used to solve the icing problem of overhead contact system.But in poor working environment,the manual de-icing method will endanger workers' life.Therefore,realizing the online automatic anti-ice and ice-melting of overhead contact system becomes immediate research focus.With the development of FACTS,large capacity reactive compensation devices have been published,which provides new ideas for the online anti-icing and ice-melting of overhead contact system.This thesis summarizes the types and formation process of icing in overhead contact system,establishes the heat balance equation of icing process and ice-melting process individually.This thesis quantitatively analyses the impacts of temperature,wind speed,relative humidity,the diameter of supercooled water droplets,illumination intensity and ice thickness on de-icing and ice-melting by drawing the relationship curve,and determines the critical weather conditions of anti-icing and ice-melting in overhead contact system.This thesis also calculates the carrying capacity of wire to verify the feasibility of alternating current ice-melting,and arrives at the method to calculate anti-icing current,ice-melting current and time.This thesis studies the working principle of STATCOM and adopts the anti-icing and ice-melting scheme of overhead contact system that installing the STATCOM at two both ends of feeding section.In this thesis,the control method,the device parameter selection of STATCOM and the model of the traction network are studied,and simulation model of anti-icing and ice-melting system of overhead contact system is build based on Matlab.The simulation results show that the anti-icing and ice-melting system has good static and dynamic property,and can control the current in the wire to meet the requirement of anti-icing or ice-melting,which verifies the correctness of the anti-icing and ice-melting scheme.This thesis designs an icing online monitoring system,including monitor terminal and upper computer software.In the part of monitor terminal design,the selection of sensor,the measurement principle of ice thickness and the design of each internal module are described in detail.Currently,the monitor terminal has been installed in supply section,worked well and met the actual operation requirements.In the part of upper computer software design,this thesis adopts VB 6.0 to write programs and SQL server 2008 to design backend database,and then designs and realizes the monitoring software which has good human-computer interaction performance,and when the overhead contact system need anti-icing or ice-melting,it can provide the corresponding solutions.