Feasibility Study On Double Side Power Supply Of Sichuan-Tibet Railway

Single-phase power-frequency unilateral power supply mode is adopted by China’s electrified railways.In order to reduce the negative sequence impact of the traction power supply system on the power grid,the substation adopts commutation connection,and sets the neutral section at the exit of the traction substation and the section post.When the train passes through the electric phase separation,it needs to be powered off for operation.The running speed of the train is reduced,and the current automatic over phase separation technology is not mature,which often leads to safety accidents.The development of electrified railway is greatly limited by the electric phase separation.This paper introduces the structure of the double side power supply system,calculates the current distribution and impedance under bilateral power supply.It also discusses the problem of balanced current under different external power connection modes,proposes a solution to the balanced current,and solves the problem of increased voltage loss in the traction substation caused by this method.Double side power supply puts forward some requirements for both power system and traction power supply system.The negative sequence current in the double side direct power supply mode is calculated,and it is pointed out that the same phase power supply technology can effectively control the negative sequence.This paper analyzes the influence on the original protection device when the fault occurs on the high voltage inlet side and traction supply system under double side power supply,and the power direction protection of low-voltage startup is added on the high-voltage incoming line side of the transformer,and the longitudinal connection protection scheme is provided on the feeder.The influence of double side power supply on the traction substation is calculated and analyzed,and the reconstruction scheme of the existing line section post is proposed.The Sichuan-Tibet Railway has a large altitude difference and a large number of long ramps.In order to avoid the installation of electrical phase separation on the long ramps to affect the safe operation of the train,a full parallel bilateral direct power supply operation mode is proposed.According to the operation plan of the Sichuan-Tibet Railway,comparing the voltage loss and current distribution of the traction network under unilateral and bilateral power supply,the bilateral power supply has the advantages of increasing the voltage of the traction network,extending the distance of the power supply arm,and improving the current carrying capacity of the conductor.Combined with the characteristics of the long ramp of Sichuan-Tibet Railway,the utilization of regenerative energy under full parallel bilateral power supply is analyzed.The feasibility of full parallel double side direct power supply method implemented on Sichuan-Tibet Railway is obtained.