Research On The Energy Absorption Of Regenerative Braking Based On Inverting In Metro

Because of shorter distance between subway stations, and the train starting and braking frequently, about 40% of the energy is wasted, and the regeneration energy which could be recycled is considerable. At present, the regeneration energy device of rheostatic absorption is commonly used in domestic subway, and the regeneration energy is consumed in the form of heating by resistors. Thus, there is waste of energy, and the heat of the resistors will cause the tunnel temperature rise and increase the burden of the ventilation facilities and the air-conditioning, and further result in energy waste. With the mastery of key technology of domestic, developing the regeneration energy device of inverting is feasible in terms of cost or technology. Thus, it is necessary to establish precise model and research the regenerative braking device based on inverting.The structure and models of traction power system in urban rail transit are analyzed in this paper, then the principle of regeneration braking and the management of excess energy are studied. The rheostatic braking which is generally used in urban rail transit at present is discussed. Considering its shortcomings, an absorbing method of regeneration energy based on inverting is proposed. The regeneration energy return to AC middle voltage power net by inverting, supplying power for other loads. Thus, it is helpful to save energy and improve environment. The absorbing system of regeneration energy is modeled in MATLAB/SIMULINK, and then the absorbing process of regeneration energy is studied. The model is composed of main circuit and control circuit, and digital PI control model is used to achieve close loop control in control circuit. Then, the harmonics in simulation output are analyzed by Fast Fourier Transform Algorithm (FFT). The results of simulation and check show as follow. Both the voltage and the current of simulation output are approximately same with the theoretical value, and the harmonics content meets the requirements. Finally, the test scheme and the protection configuration of the absorbing device of regeneration energy are analyzed in detail, to ensure that the test scheme will not affect the safe operation of traffic and the system.