Research On Metro Stray Current Control Technology Based On DCAT Traction Power Supply System

With the acceleration of urbanization,metro has developed rapidly.In practical applications,the rail as a recirculation device causes the stray current problem in the metro,which affects the normal operation of the metro electrical equipment and corrodes the surrounding metal pipeline.Therefore,it is of great significance to study the metro stray current control scheme based on direct current auto-transformer(DCAT)traction power supply system.This article will analyze and study from the following aspects:Firstly,on the basis of summarizing the research status of stray currents in metro,establishes the distribution model of metro stray currents,determines its mathematical analytical formula by micro-element method and conducts simulation research.At the same time,the influence of the parameters of the metro recirculation system on the distribution of stray current is analyzed,which lays a theoretical foundation for the stray current control scheme.Based on the above model,the DCAT traction power supply system for controlling stray current is studied.Analyze the components and working principles of the DCAT system and derive the mathematical model of the system’s stray current distribution.The DCAT system is compared with the existing system to verify that the DCAT system has a good effect on the treatment of stray current.According to the application characteristics of the DCAT traction power supply system,the topology and working principle of the DCAT converter are proposed.The design method of the circuit parameters of the DCAT converter and the voltage equalization effect of the DC side capacitor are studied.The simulation results show that the DCAT converter can achieve good capacitance equalization eflfect and zero current turn-off of the switching device.Finally,a small-capacity rail potential dynamic hardware emulator(RP-DHE)was designed and constructed to reproduce the dynamic electrical behavior of the train.It serve as a dynamic test and functional verification platform for DCAT.On this basis,a small prototype DCAT traction power supply system experimental prototype was built,including DCAT device and RP-DHE device.The experimental results are consistent with the theoretical and simulation results,which proves that the DCAT system can reduce the amplitude and action range of the orbital potential,thus making effective treatment for stray current.