| The Sichuan-Tibet Railway,as the main route for external transportation in the Tibet Region,is of great national defense and strategic significance for China.The Sichuan-Tibet railway spans seven rivers and eight mountains;the climate is harsh and changeable,and the power grid conditions are extremely weak.It is one of the most difficult projects throughout the world.In the face of continuous long ramps,the extremely abundant regenerative energy returned to the traction network by the locomotive will bring about a series of problems such as power quality,current impact,energy waste,etc.It intensifies the difficulty of designing the traction power supply system of Sichuan-Tibet line.Therefore,it is of great practical significance and social value that this paper studies the regenerative braking energy utilization scheme applicable to the weak electrified railway on the Sichuan-Tibet line.Firstly,the regenerative braking energy is simulated and studied in detail under the special climate conditions of Sichuan-Tibet area.The wheel-rail adhesion has a great influence on the traction calculation in the plateau and cold environment.In order to describe the characteristics of the regenerative energy of the Sichuan-Tibet line more accurately and improve the safety of railway transportation,based on the traditional traction calculation theory,this paper combines the wheel-rail adhesion theory with the traction calculation theory.The calculation steps mainly include the establishment of the wheel-rail adhesion coefficient model,the correction of the traction/braking characteristic curve,and the correction of the traction quality.Combining the relevant design parameters of the Sichuan-Tibet Railway,the proposed method is used to simulate the traction load of the Sichuan-Tibet Railway under three conditions of dry rail,wet rail and ice rail.The results show that it gets the largest traction quality under dry rail conditions with the weight of 2500 tons;the regenerative braking energy produced by a single-travel locomotive is extremely large with the maximum of 16 MW.The regenerative energy sent back to the traction substation with strong impact and large energy,shows the characteristics of both power and energy.Secondly,based on the above regenerative energy characteristics,combined with the actual needs of the Sichuan-Tibet Railway,a hybrid energy storage scheme based on Railway Power Controller(RPC)is proposed.In order to realize the energy circulation and power quality improvement of the two power supply arms,the RPC optimization control strategy is studied.Based on the analysis of negative sequence and harmonic compensation methods,the RPC optimized compensation control method is proposed.In order to realize the complementary technical characteristics of power-type and energy-type energy storage media,a hybrid energy storage control strategy is studied.Under the premise of considering the shallow charge and shallow discharge of the battery,based on the moving average filter theory,the design of the internal coordination control strategy for the dynamic adjustment of the limited power is completed.The simulation model is built in MATLAB/Simulink,and the results show that the scheme improves power quality while realizing the recovery and utilization of regenerative braking energy.It verifies the feasibility of applying the hybrid energy storage system based on the RPC architecture to railway high-power regenerative energy scenarios.Finally,based on the load simulation data,the parameter configuration and operation optimization of the hybrid energy storage system of the Sichuan-Tibet Railway are completed.Based on the whole life cycle theory,a hybrid energy storage optimization configuration model is established with the goal of minimum daily investment.Considering the impact of load impact on the operating life of energy storage media,the operating life of batteries and supercapacitors is quantified as depreciation coefficients based on the theory of cumulative fatigue damage and cycle life loss theory.The particle swarm optimization algorithm is used to solve the configuration results of various parameters in the single energy storage scenario and the hybrid energy storage scenario.Analyze in aspects such as configuration capacity,configuration power,operating life,operating performance,investment income and so on.The results show that the hybrid energy storage system can realize the technical cooperation of super capacitor and battery compared with the single energy storage application scenario,and achieve the dual purpose of economic optimization and operation optimization. |
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