Research On The Influence Of Electric Railway Bilateral Power Supply On Power System And Countermeasures

The management mode of China’s power system determines that the current electrified railway traction power supply system can only adopt unilateral power supply.With the development of railways,especially under the promotion of "the Belt and Road" Russian high-speed rail project,the bilateral power supply of electrified railways has caused the attention of Chinese railway researchers and designers.The implementation of bilateral power supply can not only increase the voltage of the traction network,reduce the loss of the traction network,and improve the power supply capacity of the traction network,but also solve the current power supply "bottleneck" at the end of the power supply arm of the high-speed railway traction network.However,the balanced current caused by the voltage difference between the two traction substations causes a large amount of circulating power to be injected into the power system,which hinders the wide application of this power supply method.Therefore,it is of great significance to study the influence of the bilateral power supply of electrified railways on the power system and find a method that can reduce the balanced current effectively and flexibly.Firstly,according to the external power supply mode of traction power supply system,the bilateral power supply mode is divided into two kinds: tree bilateral power supply mode and parallel bilateral power supply mode,and the balanced current under the two power supply modes is analyzed.Then,according to the equivalent circuit of the parallel bilateral power supply system,the expressions of the active and reactive power output by the phase-lagging substation under no-load and load 1 locomotive and 2 locomotive conditions are derived,and a three-dimensional graph is drawn in combination with actual parameters.Then the influence of phase difference and locomotive position on the shunt coefficient of traction substation is analyzed,and the traction network voltage loss formula of unilateral power supply and bilateral power supply is derived.The power supply advantages of bilateral power supply are verified through calculation examples,and the influence of phase difference on the voltage loss of the traction network is analyzed.Secondly,the influence of the bilateral power supply of the traction power supply system on the power flow and voltage of the power system is explored with the IEEE14-node test system.Combined with a single-phase traction transformer,a voltage phase shifter that can adjust the feeder voltage of a traction substation is proposed,and the control measures of the voltage phase shifter are given.Then,a parallel bilateral power supply system simulation model including a voltage phase shifter is built to explore the balanced current situation of the traction network under different phase differences when there is no load.Through three cases,the feasibility of the proposed voltage phase shifter was verified.At the same time,taking one locomotive on the traction network as an example,the influence of phase difference and locomotive position on the output active power and transmission loss of the traction substations before and after the installation of the voltage phase shifter is explored.Finally,based on the measured voltage data of two adjacent traction substations of a certain railway,a simulation analysis is carried out.The results show that the proposed voltage phase shifter can control the phase difference within 0.5°,effectively reducing the circulating power flowing through the traction network.