Research On Suppression Scheme Of Train Regenerative Braking Failure Based On Energy Storage

There are many long ramps for electrified railways in difficult and dangerous mountainous areas in western China,and the long regenerative braking time and high braking power of trains cause regenerative braking failure at the end of the power supply arm,which not only reduce recovery of braking energy,but also affects driving safety.Ensuring that the voltage of the traction network is maintained at a normal level is the most effective approach to solve the failure of trains’ regenerative braking.Considering that static var generator and railway power conditioner can adjust the voltage of the traction network by reactive power compensation or energy integration,combined with the current energy storage medium supercapacitors that can charge and discharge at high power,regenerative braking failure suppression schemes for electrified railways based on energy storage is studied.The main research contents of this paper are as follows:Two regenerative braking failure suppression schemes are proposed,and the energy flow characteristics of the system under different operating conditions are studied.Compared with the two terminal network voltage adjustment schemes,the proposed scheme can greatly improve the utilization rate of train regenerative braking energy and realize load peak shaving and valley filling while compensating the terminal network voltage and suppressing the failure of train regenerative braking.When the length of the power supply arm in the double-track AT traction power supply system is 20 km,25km,and 30 km,the required capacities of the energy storage device are 708 k Wh,1100 k Wh and 2348 k Wh,which can achieve single-train regenerative braking failure suppression.The system hierarchical control strategy of coordinated control of active and reactive power under the two schemes of energy storage is studied.Based on the characteristics of the four-quadrant converter,the five working states of the converter are divided,and the working state transition conditions and processes are studied.The active and reactive power distribution method of the converter is studied,and the power margin of the converter is utilized to the maximum,and the power distribution problem of the energy storage device under the second energy storage scheme is solved.The lower control designs the outer loop control with the root mean square value of the terminal network voltage as the control target.The converter adopts the current control method based on the dq coordinate system to achieve the active and reactive power coordinated control.Based on the MATLAB/SIMULINK simulation platform,simulation models of the two proposed schemes are built to simulate and the system power flow and converter working state switching under different working conditions are analyzed.The simulation results show that the proposed scheme can suppress the failure of train regenerative braking and support the terminal voltage of the traction network,and take into account the energy recovery of regenerative braking and peak load shaving.