Research On Networked Support Power Supply Scheme Of Urban Rail Power Supply System

In recent years,the scale of urban subway network has been expanding.In order to meet the requirements of urban rail transit network construction,the problem of urban rail power supply system resource networked sharing and the problem of power dispatching at the level of network have important research significance.Some cities propose to set up medium-voltage support lines between substations of different lines at the same interchange station.In extreme fault situations,the external power supply of this line and adjacent lines are used at the same time to support the power-loss area.However,under the background of this project,there is still a lack of theoretical guidance for the selection of networked support power supply scheme,the influence of networked support power supply mode on service restoration is not clear,and the feasibility and necessity of implementing networked operation project is still lacking of case analysis.Therefore,based on the operating characteristics of the urban rail power supply system and the safety requirements of urban rail transit,it is of great significance to reasonably determine the optimal support power supply plan and analyze the restoration capabilities of different support power supply methods.In the context of networked operation at the transfer station of multiple line power supply systems,this paper introduced the networked support power supply method in which the power-loss area shares the external power supply of adjacent lines,analyzed the topological characteristics of the urban rail medium voltage network,and proposed a topology modeling method of urban rail power supply system.The topology model of the urban rail power supply system laid the foundation for the simulation of different fault situations and the solution of the optimal support power supply scheme.Firstly,a supporting power supply model considering dispatch rapidity and operation economy was proposed.The constraint condition of supporting power supply was established under the condition of normal operation of all traction stations.The objective function containing two supporting power supply optimization objectives was established.By the hierarchical optimization method,the candidate scheme set with the least number of switching operations was first generated through topology search,and then the optimal scheme with the least additional active power loss of the medium voltage system was determined through the power flow calculation.Then,a supporting power supply model considering the N-1 criterion of the DC traction power supply system,different full-day traffic plans of multiple lines,and the third class load removal in the redividing power supply area was proposed.The constraint condition of supporting power supply was established under the condition of fault disconnection of any traction station.The evaluation system of optimal supporting power supply scheme was proposed,which took into account the results of traffic recovery and system operation performance.When generating the candidate schemes,the traffic recovery index was used to check the constraint conditions under the requirements of N-1 criterion first.When determining the optimal scheme,the weight of each system operation index was determined by the Analytic Hierarchy Process(AHP),and the relative closeness of each candidate scheme was calculated by the technique for order preference by similarity to an ideal solution(TOPSIS).This paper took the distributed power supply system of 5 lines as a research example,and designed 4 kinds of failure modes of external power supply and medium voltage line with different severity.Aiming at all the failures in the power-loss area including the transfer station,based on the above two types of support power supply models,the optimal support power supply plan and results were solved before and after the network operation at 10 transfer stations.It not only analyzed the specific influence of the network support power supply mode on the restoration capability,dispatching rapidness and operation economy of the urban rail power supply system,but also analyzed the specific influence of the network support power supply mode on the reliability of the DC traction power supply system,the daily traffic plan of the lost power line and the third class load recovery degree in the station.In addition,the advantages and influencing factors of each network support power supply mode were analyzed in detail,and the advantages,disadvantages and applicability of the two kinds of support power supply models were compared and analyzed.