| With the rapid development of power electronics technology and control technology,electrified railway represented by high speed and heavy load has been greatly developed.As the electrified railway trains is a single-phase asymmetric load,the power quality problems such as negative sequence and harmonic pollution are brought to the public grid after its connected to the power system.When the train employed regenerative brake,the vast major-ity of braking energy will be sent to the power system,the power department charges the railway department for regnnerative braking energy,which is infavorable for the efficient operation of the railway department.Therefore,this paper studies an AC-DC-AC converter d of recycling regenerative braking energy from 27.5kV traction power supply network to the 10kV power supply system of the railway,and focuses on the research of regenerative power direction,power estimating,system matching and so on,to ensure that the energy recycling system is stable and reliable.Firstly,the energy recycling technology of energy consumption,energy storage and en-ergy feedback is analyzed.The working principle of several recycling methods is analyzed in detail.Besides the comparison is made from various technical indexes between these method.The comparison results show that the AC-DC-AC feedback device is a kind of reasonable and superior energy recovery technology,which takes the regenerative energy back to the railway 10kV power supply system.Secondly,the working principle of independent station feedback system is studied,and the working principle of each unit of the system is analyzed.Combined with the features of phase change between voltage and current in the process of traction to regenerative braking,a superior phase measurement method is selected.According to the feature of grid-con-nected current,a control algorithm is proposed to limit the peak and average value of grid-connected current.The control strategies of single-phase pulse rectifier with direct current control and forecast current control are compared with the performance factors such as pow-er factor correction,DC side voltage ripple size and dynamic response speed.These perfor-mance indexes are analyzed and compared by simulation,and selected appropriate control strategy for rectifer.Finally,the theoretical basis of the cascade type energy feedback device is analyzed,and the correctness of the theoretical analysis is verified by simulation.Then the grid control strategy of energy feedback system is studied.Firstly,the equiva-lent mathematical model of cascaded three-phase bridge grid-connected inverter is ana-lyzed,and the relevant parameters in the equivalent model are deduced.Then,the control strategy of the cascaded three-phase bridge inverter system with LCL filter is analyzed in detail.The control strategies of current inner loop and voltage outer loop are studied respec-tively.According to the deduced transfer function of system,we can proves the stability of system.The simulation results show the feasibility of the system control.Finally,the energy feedback system with active filtering function is analyzed.The fea-sibility of the function of harmonic compensation in the energy feedback system is studied when no regenerative braking energy is generated.The related control strategy of the active power filter is studied which is based on the cascade three-phase bridge topology.Finally,the correctness of the theoretical is verified by simulation. |
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