Study On Protective Configuration Of Bilateral Cross-coupling AT Traction Power Supply System

With the rapid development of China’s high-speed railway and the continuous improvement of train operation speed break,higher requirements are put forward for the power supply quality and reliability of traction power supply system.For some places where the external power supply is weak and can not meet the needs of high-speed railway operation,needs of high-speed railway,Bilateral power supply can significantly improve the voltage level of the traction network and improve the current distribution of the traction network,so as to reduce the power loss of the traction network,prolong the power supply distance and reduce the setting of electric split phase at the section post,so as to improve the train running speed and increase the safety and stability of operation.In order to solve the problem of relay protection configuration and setting of bilateral power supply system.By building the equivalent circuit model of bilateral cross-coupling AT power supply traction network,the short-circuit impedance and current of T-R,F-R and T-F are analyzed theoretically.The influence of transition resistance on protection is analyzed combined with theoretical formula and simulation.This paper analyzes the deficiencies of the existing distance protection under unilateral power supply when applied to bilateral power supply mode,and puts forward an improved scheme for the configuration and setting of distance protection under bilateral cross-coupling AT power supply mode.Through the short-circuit impedance and current analysis of AT post and sectioning post,the power supply arm joint tripping scheme based on impedance protection and current protection is configured to distinguish the fault lines and reduce the scope of power failure.By analyzing the impact of external transmission line fault on the relay protection at the side of traction power supply system,a new protection is added to the incoming line of traction substation to prevent the impact of external transmission line fault on the stability of traction power supply system.The simulation results of the bilateral cross-coupling AT power supply traction network model built by Matlab / Simulink verify the correctness of the equivalent circuit and the derivation of the short-circuit impedance formula.Through simulation research,it is found that the short-circuit impedance and short-circuit current distribution of bilateral power supply and unilateral power supply are different,and criteria are added for current and distance protection to avoid misoperation.The bilateral power supply system under different operation is configured and set.This paper enriches the research on the relay protection of bilateral traction power supply system,which is conducive to improving the reliability of traction power supply in China’s railway system,provides an important theoretical basis for the development of higher-speed railway traction power supply system relay protection in China,and has great theoretical and practical value for the development and exploration of high-speed railway.