Research On Energy Management Control Strategy Of Metro On-board Super Capacitor Energy Storage Systems

With the development of the economy and social progress,the continuous development of the urban rail transit system based on the subway has brought convenience to people.Due to the short distance between subway stations,the train starts and stops frequently.During the acceleration process,the power demand is large,and the DC traction network voltage fluctuates drastically.During the braking process,a large amount of regenerative braking energy is not effectively recycled,which causes wasting of energy.In view of the above problems,this paper takes the vehicle super capacitor energy storage system as the main research object,and studies the charge and discharge control strategy of super capacitor energy storage system and the recovery and utilization of regenerative braking energy.Firstly,this paper introduces the characteristics of super capacitor and its working principle,and builds a model to simulate the characteristics of its charge and discharge.Then the traction substation module,traction network module and subway train module in the whole rail transit system are studied separately.The subway car module simulates the running of the subway in acceleration,idle and braking conditions by the change of the rotational speed of the permanent magnet synchronous motor.The motor vector control system is used to build a rail transit experimental simulation platform.Then,the DC/DC converter is used to realize the bidirectional flow between the regenerative braking energy and the super capacitor.The state space averaging method is used to establish the mathematical model of the super capacitor energy storage system.Through the further derivation and analysis of the transfer function,the PI control is obtained.The charging and discharging control strategy of the super capacitor energy storage system under the algorithm is the double closed loop control strategy of the inner loop of the voltage outer loop current.The simulation results show that the vehicle super capacitor energy storage system under the double closed-loop control strategy can effectively suppress the DC traction network voltage fluctuation during the subwaytrain operation,and effectively recycle the regenerative braking energy during the braking process.Finally,this paper proposes a new super capacitor energy storage system charging and discharging control strategy,namely the super capacitor sliding mode control system based on RBF network.The RBF neural sliding mode controller was designed in Buck mode and Boost mode respectively,and simulation experiments and comparison analysis were performed using Matlab/Simulink software.The experimental results show that compared with the PI control algorithm,the sliding mode control has strong robustness and fast response speed,after combined with the neural network control,it effectively suppresses the jitter caused by the sliding mode control and maintains the grid voltage stability.The control strategy also improves the recycling effect of the regenerative braking energy and achieves the goal of energy saving and emission reduction.