Research On Influence Of DC Grounding Electrode On Railroad Step Voltage And Traction Transformer Of Electrified Railway

This paper mainly studies on the influence of DC grounding pole of HVDC on railroad step voltage and traction transformer.Firstly,introducing the DC grounding pole shape commonly used in engineering.Then,The principle and size of current generation in DC grounding pole under single and double pole operation modes of DC transmission system are analyzed.And the calculation formulas of the first and second type of step voltage are derived.Simultaneously,basing on several common power supply methods used in electrified railway engineering,the mechanism of DC current intrusion traction transformer is analyzed.Secondly,building on the collected actual parameters of Zalute-Qingzhou ±800kV UHV DC transmission line system and the electrified railway,the model of the electrified railway was established in the power simulation software CDEGS.Via a single experimental variable method,the specific relationship between the railroad step voltag and the DC grounding pole ground current,the DC grounding pole and the rail vertical distance,the rail transition resistance are calculated.Finally,the mathematical model of traction transformer,locomotive and feeder is established in CDEGS in order to calculate the DC current of the intrusion traction transformer when the train passes the railroad.Moreover,the mathematical formula of DC current of the intrusion traction transformer is deduced.The DC current value flowing into the traction transformer is calculated when the train travels to different positions on the track.The simulation data fully verify that the DC current flowing through the traction transformer is affected by the DC ground current,the vertical distance between the DC grounding pole and the rail,and the relative influence of the DC grounding pole and the relative position of the traction.At the same time,the engineering solution is proposed.Through the simulation results in CDEGS,the accuracy and feasibility of the mathematical model of electrified rail,traction transformer,locomotive and feeder are fully verified.Simultaneously,this paper is able to provide the theory support and engineering guidance for the measures adopted by DC grounding pole and traction transformer in HVDC practical engineering.