Research On Restraining Low Frequency Oscillation In High Speed Railway Multi-Vehicle Pantograph Raising Servicing Considering Vehicle Energy Storage

This paper takes high-speed train-traction network coupling system as the research object,tries to introduce on-board energy storage system and considers the suppression effect of on-board energy storage on the low-frequency oscillation phenomenon of vehicle-network coupling.The analysis starts from the mechanism of low-frequency oscillation of traction network electrical quantity generated by the vehicle-net coupling system,and constructs a model of low-frequency oscillation of traction network electrical quantity for multi-vehicle up-bow rectification.At the same time,a train system model including on-board energy storage is established.Finally,a cooperative control strategy considering on-board energy storage devices is proposed to suppress the low-frequency oscillation of the traction network electrical power from the train side.It is also verified through simulation analysis that the cooperative control strategy considering on-board energy storage devices achieves the purpose of suppressing low-frequency oscillations.The main research contents of this paper are as follows:(1)Investigate the structural model of the traction power supply system,investigate the system parameters through the field,and build a simulation model in Simulink that is similar to the field calculation.Derive the control model of the rectifier of the series of Chinese high-speed railway rolling stock.The stability analysis method of the cascade system impedance ratio criterion is used to analyse the system stability under multi-vehicle rising bow rectification conditions.The mechanism and critical conditions for the occurrence of low-frequency oscillations are derived by plotting the Nyquist diagram and Bode diagram of the locomotive-traction network cascade system system.Simulations are carried out in Matlab/Simulink with the phenomenon of low-frequency oscillations in the electrical quantities of the traction network.(2)Build a simulation model of an on-board energy storage system for a high-speed train.Derive the model for the energy storage train under the rising bow rectification operating condition.Consider the energy storage operation state and design the on-board rectifieron-board energy storage device hierarchical control scheme.The control parameters of the bidirectional converter are set using the parameter design method with small disturbance increments.In the simulation,the on-board energy storage output is realised in a specific power condition,and this is used as the basis for studying the low-frequency oscillation model of the on-board energy storage for high-speed railway multi-vehicle bow-raising rectification.(3)To address the stability of the on-board energy storage introduced into the coupled system of high-speed trains.The hybrid potential theory is used to analyse the stability of the energy storage type train access system.The operating conditions of on-board energy storage and the influence of the number of trains connected to the system operation are analysed.The corresponding simulation model is built and the accuracy of the calculation is judged according to the simulation results.(4)Design of a collaborative on-board energy storage-rectifier control strategy for stabilising the power input to on-board rectifier equipment.On-board energy storage technology is introduced to stabilise the power provided by the equipment to the DC(Direct Current)side of the train.At the same time,the low-frequency stability of the system is improved by introducing virtual impedance in the cooperative controller.The effect of low-frequency oscillation suppression in multi-vehicle mixed-running mode is verified in simulations.The study shows that the on-board energy storage-rectifier cooperative control strategy can not only stabilise the DC-side input voltage of the train using energy storage devices,but also improve the low-frequency stability of the system.