Co-phase Power Supply System And Capacity Optimization Analysis Based On Hybrid Compensation

With the development of electrified railways in the direction of high speed and heavy load,the problems of power quality and phase separation have become two major problems that need to be solved in electrified railways.The co-phase power supply technology is an ideal solution to these two problems.The current co-phase power supply system has the problems such as large capacity and high cost of the active compensation device,which limits the promotion and application of the co-phase power supply system.Therefore,reducing the capacity of the active compensation device is of great significance to the development of co-phase power supply technology.This paper first summarizes the main problems of the traditional electrified railway traction power supply system and the research status of the co-phase power supply system.The implementation method and system structure of the co-phase power supply system are summarized.According to the measured traction load data,the traction load characteristics are analyzed to provide data and theoretical support for the capacity analysis and design of the hybrid compensation device.The system structure and compensation principle of the newly constructed V/v wiring transformer under passive compensation and active compensation are described respectively.The active compensation capacity model is established,compare and analyze the capacity of active compensation device with two typical co-phase power supply system schemes.Aiming at the problem that the active compensation capacity is large when only the active compensation device is used,a co-phase power supply system based on hybrid compensation is proposed by combining the advantages of active compensation and passive compensation.The capacity of active devices is effectively reduced,costs are reduced,and system reliability is improved by adding passive devices.On this basis,the capacity of the passive compensation device and the active compensation device is reasonably configured,the switching strategies of the passive compensation device thyristor control reactor(TCR)and thyristor switched capacitor(TSC)are given,and the hybrid compensation model under complete compensation is established.the variation of the compensation currents of the two converters VSC1 and VSC2 of the active compensation device with the compensation currents of the passive compensation devices TCR and TSC,power factor,and load current is analyzed,the design of the TCR inductance value and TSC capacitance value of each group and the compensation capacity of VSC1 and VSC2 of the active compensation device are completed.The results show that,relative to active compensation,hybrid compensation capacity can substantially reduce the active compensation capacity by half.In order to further reduce the active compensation capacity,by analyzing the principle of power quality index optimization compensation,an active compensation capacity optimization model is established,and the particle swarm optimization algorithm is used to optimize the optimization model.After optimization compensation,the active compensation can be further reduced capacity.Finally,aiming at the problem that the traditional i_p-i_q reference current detection method cannot effectively filter the double frequency,an improved i_p-i_q reference current detection method that solves the double frequency is proposed by constructing a current signal of a lagging load current of 90°.The simulation proves that the improved method can effectively improve the current detection accuracy and response speed.At the same time,based on the established hybrid compensation model and active compensation capacity optimization model,the hybrid compensation cooperative control strategy and active compensation capacity optimization control strategy are given,the simulation examples verify the correctness and effectiveness of the hybrid compensation model,active compensation capacity optimization model,hybrid compensation cooperative control strategy and active compensation capacity optimization control strategy.The simulation results show that the hybrid compensation system has good compensation effect and dynamic response capability,effectively reduce the capacity of the active compensation device through hybrid compensation,after optimizing the compensation,further reduces the active compensation device capacity while meeting the requirements of the national standard.