Research On The Impacts Of Electric Vehicles Charging Infrastructures On The Steady Operation Of Distribution Network

As a representative of new energy vehicles,electric vehicle(EV)plays an irreplaceable role in solving the problems of environmental pollution and energy shortage in comparison to ordinary vehicles.Its large-scale development has become an inevitable trend.Grid in china is facing the problem of mass EV access,therefore,this paper mainly studies the impact of EV charging to the steady operation indexs of urban distribution network by adopting different charging strategies based on the current peak-valley TOU price,after the popularity of types of EV and configuring the corresponding charging infrastructures.A practical intelligent charging strategy is proposed in order to reduce the impact and improve the ability of acceptance to EV charging.The distribution network model and the data that the paper selected were investigated from actual distribution network in China.First,this paper sets up charging models of types of EV in different places and different charging modes.These models consider the main factors affecting EV charging load.Then the Monte-Carlo method is used to calculate charging power curve with temporal characteristics,under the current peak-valley TOU price uncontrolled strategy and the TOU price for EV strategy.Secondly,aiming at the possible impact of EV charging,the paper puts forward an intelligent charging strategy of transformer-charging point for EV charging based on the current peak-valley TOU price.The basic idea is to control the charging start time for the purpose of smoothening the total load power,and it could achieve multiobjective optimization.Moreover,two kinds of optimization program scheme are proposed,they have different optimization accuracies and speeds of optimization,and are suitable for different situations respectively.Under the three strategies,the effect of EV charging load on transformer load rate and the ability of acceptance to EV charging are analyzed,respectively.The results show that the intelligent charging strategy could balance transformer load rate and increase the ability of acceptance to EV charging.Finally,the paper takes different 10 kv regional distribution networks of a typical 110 kV urban substation in east China as the case.Under the predicted level of EV number,the impact of EV charging load on load curve,network loss,voltage deviation,the load rate of the main equipments and the main fact that restrict the ability of acceptance to EV by the three charging strategies are analyzed.The results show that the main fact that restrict the ability of acceptance to EV is the load rate of the main equipments,however,controlled strategies could meet the demand of EV charging,smoothen load,reduce loss,improve the voltage as well as reduce the load rate of the main equipments.Moreover,the intelligent charging strategy proposed is more significant.The paper could provide reference for distribution network planning and transformation after EV access in the future.