Studies On The Uncertainty Of Electric Vehicles Charging Load And Coordinated Charging

The development of electric vehicle (EV) is a significant approach of maintaining energy security and lower carbon economy, which has already been recognized by many countries overall the world. In China, as a kind of strategic and innovative product, EV is promoted to be involved in industrial application. According to our current "twelfth five-year special development of EV technology", it is predicted to be500-1000thousand EVs in use till2015, while the energy storage of power battery will research10MW/h. In that case, the load of power system will get increased, and at the same time the situations of inadequate management will badly impact the satisfaction of users. Therefore, the charge performance of scale EV application is indispensable, so as the proposal of coordinated charge strategy.Firstly, this paper presents a spatial distribution model of electric vehicle charging load based on probabilistic method, considered the uncertainty analysis of user charging behavior and combined with a large number of measured data of electric vehicle terminal from Beijing Tsinghua Science Park. Both charging start time and charging duration are considered as two key factors that affecting the time distribution of charging load. On the spatial distribution, the considered area is divided into different regions, and each of them are connected with their own time distribution model. Thus, a composite space and time distribution model of electric vehicle charging load is established. The simulation results show that this model can reflect the practical service conditions of EV, improve the calculating efficiency and also has a practical significance. At the same time, it also laid a solid foundation for the study of charging load on the power distribution network.Secondly, on the basis of the established model, the IEEE33nodes system was chose to verify the negative effects of EV uncoordinated charge on grid voltage quality and loss under different permeability. Also, the EV charging load in a Beijing summer was selected as a real example to verify the effects of uncoordinated EV charge on power grid load under different permeability. The simulation results show that the penetration level and access point location are related to the impact of charging load on the distribution network which means the further away from the source node and the higher penetration rate can cause more severe effect.Finally, a coordinated charge strategy based on Particle Swarm Algorithm was promoted in specific to micro grid. According to the strategy, the basic concepts of EV coordinated charge as well as the micro grid structure with EVs were presented. Also, the guidance mechanism and the control structures of EV coordinated charging management in micro grid were analyzed. Moreover, based on case studies and benefit analysis, the significance of coordinated charge was illustrated, while the effectiveness of this method was verified.This paper focuses on the analysis of the uncertainty of electric vehicles charging load and coordinated charging strategy. It proposes the calculation method of charging load, analyzes the charging load impact on the distribution network, and develops a coordinated charging strategy in the micro grid scenarios which serves as a reference for further comprehensive and detailed analysis of charging load and formulation better coordinated charging strategy.