The Optimal Allocation Of Hybrid Energy Storage System For Traction Power Supply System With Photovoltaic Power Generation

In the background of the Energy Internet,it will be the future development direction of the traction power supply system(TPSS)that the electrified railway consumes the renewable energy nearby.As a kind of renewable energy with high reserves and mature technology,the photovoltaic power generation will be a major renewable energy for TPSS in the future.When the photovoltaic power generation connected to the TPSS,it will be difficult to make the balance between the generation and load because of the volatility and strong randomness of photovoltaic power generation and the intermittent and fluctuation of TPSS.Therefore,it is necessary to introduce a hybrid energy storage system(HESS),which is aimed to make balance between the supply and demand.Hence,this paper will focus on HESS to stabilize the supply and demand differences between generation and load and carry out the research work of optimal allocation of HESS of TPSS with photovoltaic generation.They are mainly as follows:(1)The topology and operation of the TPSS with “Generation-Load-Storage” are analyzed.Firstly,the traditional TPSS,the TPSS with photovoltaic power generation,and the TPSS with photovoltaic and HESS are analyzed respectively.Secondly,this paper analyzes the “Generation-Load-Storage” topology and operation of power supply arm access and RPC access.Finally,the advantages and disadvantages of the two power supply modes are explained by comparing the power fluctuation and energy saving of the two modes,which will serve as the basis for future research.(2)The energy management strategy of HESS in the TPSS with photovoltaic power generation is established.Firstly,a charge and discharge power optimization strategy of HESS considering the “look-ahead” effect is established,and the charging and discharging power of HESS is corrected through the power of tie line in the “look-ahead” period and the SOC of HESS.Secondly,the improved low pass filtering algorithm is proposed to distribute the charge and discharge power of HESS.In order to optimize the battery working environment,the filter coefficients is timely adjusting through the charging and discharging power fluctuation of historical moment,which could extend the service life of the battery.Finally,the overcharge and overshoot protection strategy is adopted to prevent the storage power from entering the forbidden area of charging and discharging area,and the coordination of HESS is realized through the mutual compensation between the battery and the super capacitor.(3)The optimization model of HESS based on life circle cost is established and solved.Firstly,the bi-level optimization model of HESS is established based on the life cycle cost.In this model,the comprehensive economic benefit is the objective function of the outer layer optimization model and the electric energy saved by TPSS is the objective function of the inner layer optimization model.Furthermore,Inequality constraints are established by capacity,power,SOC and so on.Equality constraints are established by power balance,energy conservation and so on.Secondly,the optimization model is solved by adaptive geneticsimulated annealing algorithm to obtain the optimal rated capacity and rated power of the battery and super capacitor.Finally,the simulation analysis of the model optimization results and the operation of HESS is carried out combined with the actual example.Finally,the work of this paper is summarized,and the shortcomings of this research are prospected.