Mechanism And Suppression Strategy Of Low Frequency Resonance In Traction Network

During the operation of EMU,harmonic current will be injected into the traction network due to the inherent structure of its traction drive system.When the harmonic current at the side of the traction network matches some parameters of the traction network,it is very likely that the low-frequency resonance accident of the traction network will occur,resulting in traction blocking,so that the train cannot start normally.Therefore,it is necessary to study the suppression strategy of network side harmonic and traction network low-frequency resonance.Taking the vehicle network coupling system composed of full parallel at traction network and crh380 b EMU as the research object,this paper explores the low-frequency resonance mechanism and suppression strategy of traction network.Firstly,the parameter calculation,modeling and Simulation of full parallel at network are carried out.Secondly,the control strategy of crh380 b EMU traction drive system is explored,and the simulation model of crh380 b traction drive system is built.The correctness of the simulation model is verified through the simulation analysis of the operation characteristics of EMU under different working conditions.Thirdly,aiming at the low-frequency resonance of traction network,the generation mechanism of harmonic current at traction network side is analyzed,and the characteristics of harmonic current at network side are obtained.The resonance mechanism of vehicle network coupling system is studied,and the influencing factors of system resonance conditions and resonance frequency are obtained.Through modeling and simulation,the lowfrequency resonance phenomenon of traction network is reproduced,and the correctness of theoretical analysis is verified.Finally,aiming at the problem of low-frequency resonance in full parallel at traction network,two suppression strategies are given.First,reduce the number of EMUs running,and then change the input impedance at the load side to avoid matching the natural resonance frequency of the traction network with the harmonic current frequency,so as to suppress the low-frequency resonance of the traction network.Secondly,a SVG harmonic current compensation device suitable for full parallel at traction power supply system is designed to suppress the low-frequency resonance of traction network by suppressing the low-frequency harmonic current at the network side.The simulation results show that the two suppression strategies can effectively suppress the low-frequency resonance of traction network,and provide a reference basis for the operation and technical transformation of traction power supply system.