Research On EV Charging Station Planning & Reactive Power Optimization In Distribution System

With the environment deteriorated seriously,more and more countries pay more attentions to the study on new energy vehicles.As a kind of new energy vehicles,compared with the traditional fuel vehicle,the electric vehicle(EV)has lots of advantages as: high efficiency,low pollution,low noise,and it will have a very broad prospect.In order to ensure the endurance of EVs,the robust charging infrastructures are essential.In view of the research on the hotpots as EV charging station planning and etc..In this thesis,EV charging station planning is conducted.Based on EV charging station planning,by the technology of vehicle to grid(V2G),the energy batteries of idle EVs in charging station could be used to transmit its' energy to distribution system by the form of reactive power,assisting for reactive power optimization in distribution system.The rational planning site for EV charging station is directly related to the stable operation of distribution network,the power quality and development of EVs industry.EV charging station planning includes of two parts: siting and sizing.It is comprehensively considered the needs of three areas,the government,the power company and the EV users.In this thesis,according to the specific cases affecting the charging station planning,the key factors are chosen to establish a new kind of EV charging station planning evaluation system which includes 5 categories,a total of 9 indicators,then the meaning and composition of each indicator are analyzed.In IEEE54 note case of charging station siting,the Delphi method is used to quantify the various indicators according to the original data for the candidate sites.Then,based on the evaluation index system,it is combined with Analytic Hierarchy Process(AHP)and gray evaluation method to obtain the optimal evaluation value of each candidate site,providing the basis for the optimal charging station siting decision.By Monte Carlo simulation method,the EVs charging load in the area could be simulated to determine the capacity of the charging station.With EVs linked to distribution network,the power flow could change in distribution network,and the reactive power of distribution network could be surplus or inadequate,so the voltages of some nodes could be exceed the limitation,affecting the safe operation of the grid.By the technology of vehicle to grid(V2G),the idle EVs of charging station could be considered as distribution power to link to distribution system,assisting for reactive power optimization in distribution system.Therefore,the research on EV charging station assisting for reactive power optimization in distribution system has theoretical study and practical application of significance.The compensation notes of reactive power in distribution network could be chosen by the method of partition power loss/reactive sensitivity,and the costs minimum of distribution network losses and reactive power compensation devices are as the objective function,then the optimal compensation scheme is calculated by Particle Swarm Optimization(PSO)in this thesis.Results of IEEE54 note case for reactive power compensation show: that EV charging station assists for reactive power optimization in distribution system could reduce network losses and improve the operation voltage of network,meanwhile,which could save the investment costs of reactive compensation devices.