Simulation Analysis And Impact Study Of Stray Current In Metro Based On Field Circuit Couping

Metro stray current leaked into the soil through fasteners,not only affecting the main line and depot,but also invading the urban power grid through propagation paths such as soil and cable armor,entering the transformer through the neutral point,and generating DC bias hazards.Therefore,it is important to comprehensively analyze the leakage and impact of stray current in different scenarios.This paper analyzes the flow path and magnitude of rail leakage current when the insulation of rail fasteners on the main line is intact,the gauge block fails,and the iron pad fails by establishing a coupling model for the metro main line field and road.The dynamic stray current leaked from the rail is selected as the input current for accelerated electrochemical corrosion simulation experiments.By analyzing the rail polarization characteristics and electrochemical impedance spectroscopy characteristics,we can further understand the corrosion behavior mechanism of dynamic stray current on the rail.Based on the layout of the depot,considering the characteristics of no stray current collection device,one-way conduction device,and direct grounding at the end of the depot,field circuit coupling models of the Simulink resistance network model and the soil domain finite element simulation model are established respectively;The field circuit coupling model of the resistance model of the one-way conduction device and the finite element simulation model of the depot.By changing the position of the train in the depot and the magnitude of its traction current,the operating state of the one-way conduction device and the distribution characteristics of stray current in the depot under different conditions are analyzed.The analysis of the distribution of stray current in the depot and the working state of the one-way conduction device provides a model basis for the protection of stray current in the depot.Based on the analysis of the intrusion path of subway stray current into the urban power grid,the vibration and noise operation data of on-site measured 220 k V transformer DC bias state are used to predict the neutral point stray current.The stray current is decomposed by EMD,and the SGS algorithm is used to select the super parameters of the LSTM network.An EMD-LSTM based neutral point stray current prediction model is established.By comparing the error evaluation indicators such as RMSE,MAE,MAPE,and R~2 of EMD-LSTM and BP,RNN,and single LSTM prediction models,the superiority of EMD-LSTM model in predicting neutral stray current is verified.