| New energy vehicles are driven by electric energy,which are environmentally friendly and are producing low emissions as well as low noise pollution.It is an inevitable trend in the development of the automotive industry,and the construction of charging facilities is also in full swing.However,due to the duality of electric vehicles in the distribution network,being both load and power,plus the randomness and intermittent of charging facilities as a non-linear load,their large-scale promotion to the grid has a non-negligible effect on the safety and stability of the power grid.It is of great significance to plan the charging facilities reasonably to improve the utilization of land resources.Besides,selecting suitable charging stations for consumers to improve the consumption experience and carrying out safety analysis on the grid after the large-scale charging facilities are connected are also important.Therefore,focuse on large-scale charging facilities,including the operation management and service systems of large-scale charging facilities,and evaluation of the safety of charging facilities connecting to the power grid.First,build various models related to large-scale charging facilities,including: conventional charging demand forecasting model,fast charging demand forecasting model,charging station location capacitance planning model,optimal number of charging pile model,etc.,and establish a large-scale charging facility management data mining platform based on “Internet +” to realize the real-time monitoring and control of the electric vehicles and charging stations.The power load classification and analysis are carried out by the characteristic index clustering algorithm,and the comparison between two charging strategies,the space-time constraints strategy and the nearest strategy is carried out through simulation.Secondly,aiming at the information processing,storage,interactivity and security requirements of large-scale charging facilities connected to the grid,the cloud computing method and cloud platform architecture of the charging facility operation management and service system are proposed,and the key technologies of the system are studied.Then,the safety indicators of charging facilities connected to the distribution network are studied,including overload safety,voltage safety and network loss.Finally,the mathematical modeling of the 10 kV distribution network in Changzhou area is carried out and the safety evaluation index system is established based on OpenDSS software.The influence on distribution network voltage and power flow distribution of different capacity ratios is studied.The safety of the distribution network system will increase as the capacity of the photovoltaics increases within certain limits.As the charging capacity of the charging facility increases,the voltage fluctuation rate and the voltage change rate increase significantly,and the stability of the voltage level decreases,but the normal operating rate and the network loss improvement degree do not change nonlinearly,instead they become optimum but at a certain charging capacity.So the comprehensive safety analysis results of different charging capacities show a fluctuating trend,increasing with the increase of charging capacity firstlly,achieving optimality at a certain capacity,and then starting to reduce.Based on the key technology of “Internet +”,this paper establishes data mining model of charging facilities,realizes the integrated utilization of charging facilities and distribution network data collection resources through the construction of cloud platform,guides the rational economic construction and operation of charging facilities,and studies evaluation algorithm of the safety of grid connection,providing a basis for the construction and operation management of future charging facilities. |
