| It can provide practical data support for the actual operation of urban rail transit system and be convenience to operate and maintain urban rail transit power supply system that the computer technology is applied to the simulation study of urban rail transit power supply system to simulate the operation process of the train and to analyze the change of power supply system parameters.Currently,a lot of major cities are actively building rail transit in our country;therefore,the simulation of urban rail transit power supply system has a very important role.In urban rail transit system,train running interval length is short,start and brake process of the train is frequent,it will generate braking energy to return to the traction net when the train is braking.If this part of braking energy is not promptly consumed by other trains,it will lift voltage of the DC traction network,therefore,it is necessary to use braking energy absorbing device to handle the braking energy.Braking resistor type energy absorption device is the popular absorbing device in urban rail transit system;It has mature technology,simple structure and be easy to expand research.It has very important significance to simulate and study traction power supply system including the braking resistor type energy absorbing device.Firstly,the paper introduces the composition of urban rail power supply system and power supplying mode,analyzes the train braking method.Then,from the classification of train traction motor,the principle of regenerative braking energy is analyzed,by comparing and analyzing three kinds of regenerative braking energy processing method: energy consumption type,energy storage type,energy feedback type,the paper choose including the braking resistor type energy absorbing device in the subsequent simulation and study of traction power supply system.Secondly,the operation process of the train is analyzed,and the simulation algorithm flow of regenerative brake traction calculation is described in detail.Through the programming and simulation analysis of the specific examples,it can get the simulation results including “one intervals”,“multiple intervals” and train operation diagram.The simulation results can correctly reflect the train parameters changing relationship during the operation of the train,which provides the theoretical and data basis for the simulation study of the subsequent power supply system.Next,the paper separately establish DC traction power supply model with braking resistor type energy absorbing device at the train and the traction substation.Considering the influence of the braking resistor type energy absorbing device on the traction power supply system,the current vector iteration method is modified;the traction calculation result is used as dynamic load data to finish power flow calculation of DC traction network.By using MATLAB,the simulation program of "two trains-three traction substations" model is compiled,the results of the power flow calculation of the braking resistor type energy absorbing device at the train and substation are compared and analyzed.Finally,the equivalent circuit diagram and the external characteristic curve of the rectifier in traction substation is analyzed,from three parts: the DC power flow calculation,the AC power flow calculation,the interface between AC part and DC,the braking resistor energy absorption device at the traction substation is taken into account,the AC-DC hybrid power iterative algorithm is proposed.The simulation program is compiled by using MATLAB,the traction calculation of the train and the AC-DC hybrid flow calculation are combined to finish the overall simulation study,the correctness of the AC-DC hybrid power iterative algorithm is verified,at the same time,the result of the alone DC power flow calculation is compared with the result of the AC-DC hybrid power flow calculation,the influence of adding the AC part on the DC flow calculation result is analyzed. |
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