Research On Short Circuit Fault Based On Energy Fed Traction Power Supply System Model

The energy-fed traction power supply system,which is composed of 24 pulse rectifier unit and inverter energy feed device in parallel is the development direction of urban rail transit traction power supply.At present,there is a lack of research on the DC side short-circuit fault of energy-fed traction power supply system in China.For the safety and reliability of train operation,the related problems were studied.Firstly,this thesis introduced the composition structure of energy-fed traction power supply system.By analyzing the process of short circuit of energy feeding device,the output external characteristic model of energy feeding device was obtained.And the DC side short-circuit steady-state current at different short-circuit points under bilateral power supply was calculated according to the known structure and parameters of the traction power supply system.And then built on this knowledge to model and simulate the energy-fed traction power supply system using MATLAB/Simulink software.After the short-circuit fault occurred in the system,the differences in short-circuit characteristics between the energy fed traction power supply system and the traditional traction power supply system were obtained through theoretical analysis and simulation waveform,and new requirements were put forward to the DC short-circuit protection device of the energy fed traction power supply system.Overlaid on it all was deeply studied the setting principle,setting method and action cooperation relationship of DC protection in energy-fed traction power supply system.According to the simulation results of the system model,we drew the detailed configuration scheme of each component of the DC protection system in the substation.Due to the startup of short-circuit protector,the damage of the system was small.It was impossible to judge the line fault directly.According to the above problems,the feasibility of several fault location methods in the energy-fed traction power supply system was explored.The results of two terminal field fault location were obtained.In order to further improve the accuracy of fault location,the port voltage of traction substation was introduced into the fault location equation,and an improved fault location method was obtained.Because the steady-state value of two terminal electrical quantity can’t be obtained after short circuit,a two terminal ranging method based on transient initial current rise rate was proposed.The simulation results showed that the short-circuit fault location method based on transient data had higher positioning accuracy.