Study On Charge-discharge Management And Control Strategy Of Energy Storage Device For Electrified Railway

Electrified railway is a kind of large-scale industrial power users with heavy load fluctuations.The peak value of traction load power not only causes the power quality problem based on negative sequence,but also directly affects the user's benefit economically.At the same time,the problem of low capacity utilization of traction substations has also been receiving much attention.The key to solving the problem of excessive peak load power of electrified railways and low utilization of capacity in substations is whether the load energy can be reasonably distributed.Therefore,it is particularly important to study the technical solutions of flywheel energy storage devices with dual functions of electric energy storage and release for electrified railways,which can provide a theoretical basis for the application and promotion of energy storage devices in electrified railway engineering.Firstly,the necessity and feasibility of the flywheel energy storage device applied to the electrified railway are analyzed,and the corresponding technical solutions are proposed.Based on the characteristics of traction load,the peaks and valleys of traction load are defined.At the same time,the characteristics of the flywheel energy storage device of DunShi Magnetic Energy Technology Co.,Ltd.are combined.The feasibility and effectiveness of the scheme are verified by theoretical and simulation calculations.Secondly,after determining the superiority of the flywheel energy storage device for peak clipping of the traction load,the control strategy of the grid-side converter and the motor-side converter of the flywheel energy storage system of the electrified railway and the control mode of the flywheel motor are further studied.A control strategy with traction load power as the control target is proposed.The corresponding MATLAB/Simulink simulation model is built and the three working modes of the flywheel energy storage system are simulated and analyzed.The effectiveness of the control strategy and its rationality for peak-filling and valley filling are verified.Then,using the daily periodicity of the electrified railway operation map,the charging and discharging threshold of the flywheel energy storage device is determined by referring to the previous statistical value of the traction load,and the traction load curve is classified according to the mean value of the adjacent peak(valley)difference.Different types of traction loads use the optimal statistical value as the charging and discharging power threshold,and further propose a variable threshold energy management strategy.Combined with the Beijing-Shanghai high-speed rail data,the superiority of this energy management method compared to other single threshold energy management methods is verified.Finally,based on the GTR333 flywheel device of DunShi Magnetic Energy Technology Co.,Ltd.,it assisted in the construction of the 10 kV experimental platform for electrified railway flywheel energy storage.The experiments completed under the experimental platform include: flywheel discharge tracking load power experiment,peak clipping effect comparison analysis experiment,variable threshold control experiment and charge and discharge threshold effect experiment,and the experimental results and simulation results and theoretical results were carried out.Comparative analysis verified the accuracy of theoretical analysis.