Traction Load Modeling Of Metro Power Supply System And Its Influence On Power Flow Calculation

As a typical representative of urban rail transit,the subway has the characteristics of fast,safe,punctual,less pollution and vast capacity.It has become the preferred solution to ease the traffic congestion pressure in large and medium-sized cities.With the advantages of high power quality,high efficiency and energy-saving,the DC transmission mode of the subway has become the development trend of the city’s transportation in the future,on this basis.Due to the frequent starting and shutting of subway trains and the change of pedestrian flow,the subway load has great volatility.In order to better grasp the influence of the subway traction load on the power flow calculation,it is necessary to model the traction load of the subway and calculate the power flow,and analyze the results.First of all,we conducts an in-depth study on the power supply system of metro rail transit in the paper.The status of development of metro rail transit in China is introduced at present,and the research status are summarized in domestic and foreign.At the same time,the structure of the subway power supply system is elaborated in detail,especially the medium voltage power supply system and the DC traction power supply system.Secondly,the mathematical derivation and simulation analysis of stray current and rail potential are carried out.Based on the normal operation mode of subway power supply system,a track rail reflux model is established,and the numerical distribution formula of stray current and rail potential is derived.At the same time,the stray current and rail potential are simulated under the condition of single side power supply,bilateral power supply and multi vehicle running,and the factors that affect the distribution of stray current are simulated and analyzed.Thirdly,the traction load of Metro is simulated.Through the force condition of the train,the train running state and the selection of the traction strategy,on the Matlab software platform,the traction load calculation program of subway train is programmed,and the relationship between the power from the contact network and the running distance is simulated.The simulation curves of the train in the ideal line and the actual line are compared and verified.It is proved that the data of the simulation curve under the actual line state is more accurate.Finally,based on the analysis of the principle and the external characteristic curve of the 12 pulse wave finishing unit,the model of the subway DC traction power supply system is set up.The medium voltage power supply system of the subway is built with the open power network and their flow calculation flow chart.The AC and DC hybrid iterative flow calculation is used to calculate the power supply system with the AC and DC interface model,the tidal current distribution on the AC side of the metro is calculated,and the simulation results are analyzed.Lastly,according to the discriminant index of the power supply system,it is proved that the variation of the calculated data is more consistent with the actual operation,and the engineering construction personnel can provide data reference.