Modeling And Coordination Control Strategy Of Hybrid Energy Storage Intergrated Co-phase Power Supply System

The rapid development of electrified railways provides a strong energy for the national economy and the society,but it also brings more challenges to the traction power supply system.In China,the traction power supply system mainly adopts single-phase structure,which will cause some problem,including power quality problems,neutral section problems and regenerative braking energy utilization problems,affecting the safe operation of railways.The adopt of the co-phase power supply system can effectively solve the negative sequence problem,and cancel the neutral section of the substation.As a result,based on the combined co-phase power supply system,and considering the advantages of energy storage device in regenerative braking energy utilization,a hybrid energy storage integrated co-phase power supply system is proposed in this article,and its working principle and control strategy have been studied.The main research content is shown as follows.Based on combined co-phase power supply system and supercapacitor-battery hybrid energy storage system,a hybrid energy storage integrated co-phase traction power supply system(HES-CTPSS)is proposed,and its topology and working principle are analyzed.The system is divided into four working modes,according to the value of traction load,and the power flow characteristics of each working mode are studied.Taking the capacity of co-phase power supply device(CPD)as the constraint,the reference power of each port is deduced to get the minimum three-phase unbalance of the system.In order to fully take advantage of the working characteristics of supercapacitor and battery,and prevent the supercapacitor from overcharging,a low-pass filter power allocation method with variable filter constant is adopted,to distribute the power of the hybrid storage device.The control strategy of the HES-CTPSS is studied.In the converter control algorithm,a nonlinear-based control strategy for CPD is proposed,which can realize the faster power response and DC voltage track of the CPD.In the DC side voltage control of the system,two control methods are proposed,and the influence of two control methods on the performance of the system is analyzed by both simulation and equivalent circuit diagram.Based on the DC voltage control method and the nonlinear algorithm,a hierarchical control strategy is proposed,which can realize the effective switch of the different mode.Besides,in the hierarchical control,the control target of the CPD and HESD controller can be adjusted according to the different working modes of the system,and the working performance of the system is guaranteed to the greatest extent.Based on MATLAB/Simulink,and adopt the control strategy proposed in this article,the model of the HES-CTPSS is built,and the operation characteristics of the different working modes are simulated and analyzed.The result proves the effectiveness of the system in negative sequence control and regenerative braking energy utilization,and verify the feasibility of the proposed system topology and the correctness of the control strategy.