Study On Active Power Filter And Regenerative Energy About Electric Locomotives

Domestic electric locomotives are mostly rectifier type. Through a locomotive's transformer and a set of silicon rectifiers, the electric locomotive acquires what need DC to supply traction electromotor. But rectifier type power electronic components may produce harmonic current and make contact grid's current distorting. Moreover, when the locomotive operates in the regenerative brake mode, the electric locomotive doesn't draw current from the supply but produces regenerative braking current. If the regenerative energy is utilized well, much of energy is saved. So a device that is anti-parallel connected with locomotive's silicon rectifier is discussed, which eliminates harmonic current and injects regenerative energy to the AC grid.Studying on active power filter is important contents of the thesis. Harmonic detection is one of key technologies of active power filter. An adaptive harmonic current detecting method based on the adaptive noise canceling technology is researched. The principles of the adaptive noise canceling technology and the adaptive harmonic current detecting method are clarified. A number of simulations are developed, and the results show that the detection system can still normally work and has well adaptability when the waveform distortion happens to the supply grid's voltage and the fluctuation happens to the power system's frequency.For the sake of improving the harmonic detecting precision and dynamic response, an adaptive neural network harmonic current detecting method is studied, which is based on the adaptive noise canceling technology and the adaptive linear neural network theory. The adaptive linear neural network theoryand its core algorithm------LMS algorithm are introduced in detail. On the base oftheoretical analysis, a number of simulations are developed. When load currents and the supply grid's voltage are changing, the detecting method has well adaptability. But high detecting precision accords hardly with rapid dynamic response due to influence of the learning speed. So a harmonic current simulation model which the learning speed is variable is set up. The simulation results show that the detecting method is not only with high detecting precision but with rapiddynamic response as well.Pulse Width Modulation control method is another key technology of active power filter. Triangle carrier wave PWM control method is adopted in the thesis, and the running process of unipolar PWM control method is analyzed. The simulation for active power filter is developed, the results prove the proposed single-phase active power filter can eliminate harmonic current and purify the supply grid.Finally the electric locomotive's regenerative brake is simply introduced in theory, and the simulation is developed.