Simulation And Influence Research On Electrified Railway Traction Power Supply System

As the Beijing-Tianjin intercity high-speed railway, Wuhan-Guangzhou high-speed railway, Shanghai-Nanjing Intercity Railway have been opened, China's high-speed railway network construction is rapidly booming. With its advantages of speed, safety, transport capacity, low energy consumption, good economic returns, comfortable and convenience, high-speed railway become the direction of China's railway. Power supply system is one of the important subsystems of high-speed railway traction, and high-speed train is the basis research of power supply system. High-speed Electric Multiple Units (EMU) is a special kind of power system load, the harmonic and negative sequence which produced in the operation will be injected into the power system through the traction substation, have a certain impact on power quality. In order to analyze the load characteristics of high-speed EMU, it is necessary to establish its detailed and accurate digital simulation model, which make basis for the establishment of load model of traction power supply system and analyzing its impact on the utility grid.First, this paper describes the AC-DC electric locomotive drive principle, and establishes the matlab/simulink model, including freight type SS4, SS4G and passenger type SS8, SS9 electric locomotive, which use semi-controlled bridge with multi-stage thyristor and phase controlled rectifier circuit to control traction motor. Further, analyze the harmonic characteristics of the locomotive traction conditions.Secondly, detailed modeling and simulation of AC-DC-AC EMU are studied, including CRH3, CRH2 high-speed EMU. AC transmission system is mainly composed by pulse rectifiers, inverters and traction motors, the control methods including the transient direct current control of the four-quadrants pulse rectifier, three-level space vector control of inverter, the rotor field oriented vector control and direct torque control of traction motor. In this paper, a detailed matlab/simulink model of the traction drive system is established, the simulation shows the traction, coasting and braking operation conditions of EMU, and from the harmonics, power factor, the net pressure fluctuations, a sudden loss of electricity Etc. to study the load characteristics of EMU. The result of the whole system shows a good static and dynamic performance, indicates that the simulation model is correct and valid.Finally, according to the characteristics of high-speed railway traction loads, this paper analyzes its impact on power system protection, including traction transformer protection, line protection, bus protection and generator protection. The integrated model of Beijing-Tianjin high-speed railway traction and high-speed EMU is established, by simulating the transformer no-load closing and motorcycles start, analyzes the impact of transient on the traction transformer protection. Also study a brief analysis of the impact on line protection, bus protection and generator protection from the theory, especially to the start components of protection, TV broken, and negative to high-frequency protection, bus differential protection and negative sequence current protection of generators.