Orderly Charging And Discharging Strategy For Large-scale Electric Vehicles Based On Self-organized Criticality Of Distribution Network

China advocates green and low-carbon life through incentive mechanism.The new energy market continues to expand and attract consumers,and electric vehicle users are increasing year by year.In order to comply with the development of the new energy vehicle industry,the hardware and software facilities related to electric vehicles are also constantly improving.However,the access of large-scale electric vehicles to the distribution network for charging and discharging has brought great challenges to the security of the distribution network.How to maintain the safe and stable operation of the distribution network while meeting the charging and discharging needs of electric vehicle users has become a hot topic of current research.In view of the lack of in-depth analysis of the safe operation of the distribution network in the current orderly charging and discharging strategy of electric vehicles,firstly,considering that the disorderly access of large-scale electric vehicles to the distribution network will lead to the rapid evolution of the distribution network to the fault state from the perspective of the safe and stable operation of the distribution network.The orderly charging and discharging strategy of large-scale electric vehicles is considered from the internal mechanism of distribution network failure,and the self-organized critical characteristics of distribution network are analyzed with sand pile model.Secondly,based on the self-organized criticality characteristics of the distribution network,further research is carried out on how to deal with the potential hazards caused by the access of large-scale electric vehicles to the distribution network,and solutions and optimization strategies are proposed for different problems and perspectives to achieve the mutual benefit of the distribution network and electric vehicle users.The main work is as follows:(1)Considering the charging and discharging behavior of users,the number difference of regional electric vehicles,the line load rate and the line power flow,a co-evolution model of charging and discharging load and distribution network is established based on the idea of multi-sandpile model.By analyzing the self-organized critical characteristics of the evolutionary distribution network,a hierarchical adjustment strategy for different control objects is proposed from the perspective of safe operation of the distribution network.Finally,the simulation results show that the proposed hierarchical adjustment strategy can effectively slow down the growth rate of line load rate and prevent the distribution network from entering the self-organized critical state.(2)Considering the long-term,convenience and economy of power supply,a reconfiguration optimization strategy based on line load rate and system active loss is proposed from the perspective of distribution network reconfiguration.The conditions for the distribution network to enter the reconfiguration are determined by the strategy.Secondly,a switch opening and exchange strategy is proposed.This strategy first selects the line switch with the goal of reducing the active power loss of the system,and then optimizes the reconstruction results with the goal of reducing the average load rate of the line.Combining the above two strategies,the orderly charging and discharging strategy of electric vehicles based on hierarchical adjustment strategy is improved to obtain the orderly charging and discharging strategy of electric vehicles considering distribution network reconfiguration.The simulation results show that the proposed strategy can reduce the active power loss of the system while avoiding the occurrence of fault lines and balance the line load rate.(3)Considering the user satisfaction of electric vehicles,the maximum user satisfaction of charging and discharging and the minimum average load rate of the line are taken as the objective function,and the charging and discharging load transfer strategy of electric vehicles considering user satisfaction is proposed.Based on this strategy,the orderly charging and discharging strategy of electric vehicles considering distribution network reconfiguration is improved.The simulation results show that the strategy combines the advantages of the orderly charging and discharging strategy of electric vehicles based on hierarchical adjustment strategy and the orderly charging and discharging model of electric vehicles considering distribution network reconfiguration,which has better control effect than the above two strategies under the background of large-scale electric vehicles accessing to distribution network.