Energy Storage Capacity Optimization And Energy Management Strategy For Dual Application Of Traction Load

With the increase of the total mileage of electrified railway construction,while improving the level of people’s travel,the problems of high construction cost and high power consumption for operation are also more serious.Therefore,how to improve the economical efficiency of electrified railways is a hot research topic at present.Traction transformers are an important part of electrified railways.The capacity utilization rate of traction transformers in my country is only 5%-40%,and the capacity of traction transformers is directly determined by the maximum traction load.Therefore,shaving peaks and filling valleys of traction loads can improve the capacity utilization rate of traction transformers and reduce costs.In addition,in order to further reduce the electricity cost of railway companies,the direct electricity purchase transaction form advocated by the state can be adopted.The use of direct power purchase transactions refers to obtaining electricity price discounts from the power generation company by signing a power purchase agreement with the power generation company and submitting the electricity consumption at each time of the next day to the power generation company in advance.However,the traction load has the characteristics of large peak-to-valley difference and frequent state switching,so it is difficult to obtain accurate prediction results.For the load that exceeds the limit,the railway company needs to pay additional fees.If the energy storage system is used to compensate the partial load that exceeds the limit,the electricity bill of the railway company can be reduced.It can be seen from this that the dual application of shaving peaks and filling valleys of traction load and compensating prediction errors is an effective method to improve the economy of electrified railways.In order to improve the economy of dual application,this paper optimizes the configuration of the traction substation and formulates a control strategy for the hybrid energy storage system(HESS).The main contents of this article are as follows:1.Aiming at the problem that the traditional capacity allocation method does not consider the influence of prediction error on electricity cost,this paper proposes a dual application capacity allocation method of peak shaving and valley filling and compensating prediction error.Firstly,the method of single peak clipping and valley filling is analyzed,and the necessity of compensating prediction error is obtained,and the principle of dual application is introduced.Then,the economic model of the Hybrid Energy Storage Railway Power Conditioner(HES-RPC)is established in the dual application,and the particle swarm algorithm is used to solve the problem to obtain the optimal traction transformer and hybrid energy storage.system capacity.Finally,this paper substitutes the optimized parameters into the corresponding energy management strategy,and uses the measured traction load data to verify the effectiveness.2.Aiming at the problem of lack of peak shaving caused by prediction error in the dual application proposed in this paper,this chapter proposes a dual application energy management strategy that takes into account the lack of peak shaving.Firstly,the reason for the lack of peak shaving is analyzed,and a dual application target domain that takes into account the lack of peak shaving is established accordingly.According to this target domain,the power distribution of the hybrid energy storage system is performed using wavelet packet transform.Secondly,in order to avoid the internal power circulation of the energy storage system,the power direction of the system is corrected to solve the problem of internal power circulation;Make a second correction.The principle is to divide the hybrid energy storage system into 5 regions according to the size of the state of charge(SOC),and formulate the corresponding energy storage system power correction scheme according to the target domain of the traction load.Finally,the dual application advantages of taking into account the lack of peak clipping proposed in this paper are verified through experiments.