| The new AC/DC dual-system traction power supply system represents the development direction of the interconnection between the urban rail transit system and the municipal railway,and the application prospect is very broad.But,the AC/DC dual-system traction power supply mode is still blank in China,and the electrical characteristics between the "vehicle-network" and the "vehicle-rail" around the transition section are not clear.Taking the country’s first AC/DC dual-system rail transit line from the Jiangjin to the Tiaodeng line as an example,the traction backflow characteristics of the traction power supply system and the neutral section passing transient characteristics of AC/DC dual-system locomotive are studied.It is of great significance for the engineering design to provide recommendations to ensure the safe operation of the traction power supply system.This paper first studies the calculation model of rail potential and traction return current under AC and DC traction power supply systems,and obtains a mathematical calculation model of ground potential near the rails in the AC section.Based on the engineering design scheme,a traction return current system simulation model of AC/DC dual-system traction power supply system was built,and compared with the theoretical calculation results,the correctness and effectiveness of the model were verified.Secondly,the combined potential limit of the rail suitable for AC/DC dual-system traction power supply system is proposed.The influence rule and sensitivity of the length of the non-electrical zone,the transition resistance,and the soil resistivity on the combined rail potential are analyzed.And the variation rule of the combined rail potential whether the non-electric section is provided with a rail insulation joint is studied.Then,combined with the different electrical split-phase design schemes of the AC/DC dual-system traction power supply system,the main electrical parameters were calculated,and the equivalent circuit corresponding to the AC/DC dual-system locomotive passing the neutral section was established,and the formula for calculating transient overvoltage is derived.Subsequently,the design scheme of electric phase splitting of AC/DC dual-system traction power supply system is given.The calculation formula of the neutral section passing transient process of AC/DC dual-system locomotive is derived.The neutral section passing transient model for AC/DC dual-system locomotive was built.Finally,the simulation model of each phase of the transient process of the dual-system locomotive passing through the electrical phase splitting was built,and the variation rules of the transient overvoltage of each phase of the AC/DC dual-system locomotive passing the split phase under different electrical phase splitting schemes were studied.The influence law of catenary voltage phase,traction network harmonic voltage on the overvoltage is analyzed.An effective overvoltage suppression scheme is proposed,which provides an important reference for engineering design. |
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