Performance Analysis Of Bilateral Power Supply System In Electric Railway

The electric railway has been using single power supply mode in our Country decided by the operation management system of the power system. With the development of power system, the voltage of the grid has been promoted to 220kV and some strong power grid has even reached 500kV. Set the co-phase power supply device in the traction substation has managed the power quality problems such as harmonic and negative sequence, meanwhile, the primary side hasn’t exchanged the connection and canceled the electrical separation at the exit of substation. The improvement of the power grid and the traction power supply system makes it possible to achive bilateral power supply of the electric railway. The implementation of bilateral power supply has canceled the electrical separation in the partition, which is advantaged to the high speed train. While, the bilateral power supply produces large equivalent current which is not accepted by the power system.Therefore, it is important to put forword a method to solve the equivalent current and verify its feasibility, investigate the effect on the power system and the traction power supply system.First of all, this paper has researched and summaried the connection mode of traction power supply system and electric power system, put forward the bilateral power supply system with series reactor connected in the traction feeders of the substation improved from the traditional bilateral power supply. Besides, analyzed the equivalent circuit, parallel impedance ratio, the control technology of voltage loss in the traction substation and the influence of series reactor to the traction load current, voltage loss, power loss and traction transformer capacity. Discussed the energy metering implementation of bilateral power supply caused by the equivalent circuit and the electric power metering standard of the traction power supply systemSecondly, conducted a theoretical derivation of the short-circuit fault in power system and traction power system, which included short-circuit current and impedance. Built the simulation model in Matlab/Simulink software included equivalent current, the short-circuit fault in power system and traction power system, and compared with the theoretical calculation. The simulation results has showed that:the series reactor could reduce the equivalent current and short circuit current of the traction power supply system, depress the fault current of the power system and the influence of relay protection device.Finally, analyzed and summarized the scheme of feeder protection, the protection range of the substation and partition, and the typical fault of feeder protection of the bilateral power supply. Also, put forward the relay protection scheme for different power supply mode after fault reclosing. Briefly introduced the traction network’s section and monitoring scheme of the bilateral power supply, and showed its importance to the relay protection of bilateral power supply system.