Research On Distribution Network Fault Location And Restoration Evaluation Based On Graph Computation

In order to alleviate the pressure of environmental degradation and energy shortage,renewable energy has developed rapidly.with the characteristics of high energy efficiency and low pollution of new energy electric vehicles,the popularity of new energy electric vehicles is increasing nationwide.However,at the same time,the fluctuation and uncertainty caused by the output of distributed generation(DG)and the grid connection of electric vehicles(EV)also cause the problem of insuffieient flexibility of active distribution network(ADN),which has a great impact on the safe and stable operation of distribution netwotk.Therefore,it is of great significance to make full and reasonable use of various flexibility resources in ADN to improve the flexibility of ADN.This paper focuses on the multi-objective ADN flexibility improvement method of electric vehicle orderly charging strategy and energy storage system(ESS)optimal configuration.The main work is as follows:Firstly,considering all kinds of flexibility resources in ADN,the flexibility evaluation index of ADN is established from the power supply side,distribution network side and load side,and the evaluation method of flexibility index is proposed.Through the IEEE33 node example system,the ability of the established evaluation index and evaluation method to evaluate the flexibility of ADN is verified.Secondly,considering the uncertainty of DG output.Based on the stochastic model of windsolar output,the load characteristics and wind-solar output characteristic curves are generated by Latin hypercube,and the typical wind-solar output curves are obtained by K-means clustering reduction for the planning of energy storage.The influence of EV disorderly charging on ADN flexibility is quantitatively evaluated by flexibility index.Then,for the distribution system with high permeability DG and large-scale,EV grid connection,a flexibility improvement model for orderly charging and energy storage optimization configuration of electric vehicles is established.The model takes the highest comprehensive score of flexibility index,the minimum charging cost of users and the minimum comprehensive cost of distribution system as the optimization objectives,and uses multiobjective particle swarm optimization algorithm to solve the model.Finally,through the standard IEEE33 node system,the rationality of the flexibility improvement model established in this paper is verified.The improvement effect of charging load and net load fluctuation of electric vehicle in each period after reasonable guidance of EV orderly charging is analyzed compared with that of disordered charging.The charging and discharging power of energy storage in each period after optimal configuration of energy storage is studied.The results of multi-objective optimization in flexibility improvement are analyzed by the comprehensive score of flexibility index.The results show that reasonable guidance of orderly charging of electric vehicles and optimization of energy storage configuration can effectively improve the flexibility of active distribution network.