Capacity Optimization Design Of Railway Static Power Conditioner With Energy Storage System Based On Load Uncertainty Analysis

With the development of economy and society,people's demand for public transportation is increasing year by year,thus the public transportation occupies an increasingly important part of national economy.Thanks to the progress of technologies,electrified railway has developed rapidly in recent decades and has gradually become an indispensable part of daily life of human being.However,as we all know,the power supply of electric locomotive has asymmetry and fluctuations,and there has uncertainty and asymmetry caused by the electrified traction power grid structure.And with the comprehensive fluctuations,all these bring the traction power supply system power quality problems,including negative sequence component,large reactive power content and obvious harmonic.All these problems will not only affect the stable operation of traction system itself,but also affect the power quality of other users along the traction grid.Based on the existing researches,Railway Static Power Conditioner(RPC)has a good comprehensive governance ability in balancing active power,compensating reactive power,reducing negative sequence component and reducing harmonic content,etc.,which is one of the important future research directions of electrified railway development.However,the traditional RPC still has some disadvantages in solving the above problems,including the economic problem of excessive compensation capacity or insufficient compensation problem of too small compensation capacity caused by idealization load analytical method.And there is also a waste of regenerative braking energy that cannot be stored by the traditional RPC.Therefore,this paper makes an indepth study on the capacity parameters problems of RPC and its related structures,and the main researches and innovation points are described as follows:In traditional schemes,a fixed value is used to represent the load limit and the load handling method,without considering the uncertainty of traction load.It will probably cause a bad compensation consequence with an insufficient compensation capacity or a poor cost performance with a huge compensation capacity.Thus,a Multi-scenario Analysis method considering the uncertainty of traction load is introduced.In this method,the fluctuating load is analyzed and processed first,and then it is analyzed by Clustering Algorithm,and the fluctuating load is classified into several operational scenarios reflecting its operating characteristics.This kind of data analysis method and processing method take the load uncertainty into account and which is more in line with the actual load operation.In view of the problems of large load fluctuation and large compensation capacity of the two power supply arms of the power supply system under the traction condition of the traction system,this paper proposes a multi-scenario capacity optimization design of railway static power conditioner considering Load Uncertainty.By establishing the optimization model,the optimized RPC capacity was calculated after the traction load multi-scenario analysis.Calculating optimization compensation capacity of each scenario,and finally,the compensation capacity suitable for every scenario is obtained.This method can improve the economy of RPC while meeting the compensation requirements.And finally,its effectiveness is verified by simulation experiment and comparative analysis.For regenerative braking traction load conditions,the regenerative braking energy generated regenerative braking locomotives fed into the traction grid through the transformer.The regenerative braking produces negative sequence current and other power quality problems to the electrical equipments.An energy storage type RPC is adopted,and its energy storage system is introduced in this paper.Through the analysis of electrification model of energy storage type RPC,a model of its participation in regenerative braking energy utilization and peak and valley load regulation is constructed.Then,the economic cost models and benefit models of the traction system of substation are established.An optimization model was established to maximize the comprehensive economic benefit,and the optimized configuration capacity of the energy storage system of energy storage type RPC was obtained.Finally,the simulation experiments are carried out in MATLAB,and the effectiveness of the method is verified by the simulation results and contrastive analysis.