| Governments and related companies in various countries are vigorously promoting the development of electric vehicles,with a view to gradually replacing traditional internal combustion engine vehicles,so that the environmental pollution caused by the continuous increase in energy consumption can be alleviated.As more and more electric vehicles are connected to the grid,it will inevitably have an impact on the stability of the grid.On the one hand,the uncontrolled charging of a large number of electric vehicles will affects the stability and economy of the power grid;on the other hand,with the development of on-board communication technology,the power grid’s ability to dispatch electric vehicles is gradually strengthened.With the help of V2G(Vehicle-to-grid)technology,electric vehicles can even be treated as a distributed energy carrier,which can not only consume excess wind,light and other renewable energy,but also provide the grid with ancillary services,like peak-valley shaving and frequency regulation,through reasonable charging and discharging scheduling strategies,to improve the stability and economy of the power grid.This paper takes electric vehicles in the power grid as the research object,studies the impact of different electric vehicle charging/discharging strategies on the charging demand and the power grid,and compares the average daily cost of electric vehicles under different scheduling strategies.The specific research goals of this paper include:(1)The average daily electricity demand,the spatial-temporal distribution of the charging load,and the impact on the grid of electric vehicles under uncontrolled charging strategy;(2)The changes in the charging demand and cost of electric vehicles under the controlled charging strategy,and the charging and V2G potential of electric vehicles under the unified dispatch of the grid;(3)The impact of electric vehicle on the power grid,,and the cost of V2G,under the joint optimization of the vehicle and the grid.In order to achieve the above goals,firstly,based on the US National Household Travel Survey(NHTS)database,study the spatial-temporal characteristics of electric vehicle travelling,extract the input feature values required for modeling,and then use the multi-agent based method to build a trip chain model which has high special-temporal accuracy.The output of the trip chain model is compared with the real data from NHTS database to verify the accuracy of the modelSecondly,three different charging/discharging strategies for electric vehicles are studied-the current ubiquitous uncontrolled charging strategy,the controlled charging strategy of unified dispatch of the power grid,and the jointed optimized scheduling strategy for electric vehicle and grid.A Innovative global optimization algorithm is then proposed,through rolling iterations in the day-ahead optimization process,to obtain the optimal scheduling strategy under jointed optimized scheduling strategy for electric vehicle and gridFinally,the impacts of the three different strategies are studied.Under the uncontrolled charging strategy,the special-temporal distribution of electric vehicle charging load and its impact on the grid is studied;under the controlled charging strategy,the electric vehicle charging load,impact on the grid,and cost changes are studied.Besides,the charging and V2G potential of electric vehicle under the unified dispatch of the grid is analyzed.Under the jointed optimized scheduling strategy for electric vehicle and grid,the impact of electric vehicles providing peak-valley shaving services is studied,and the cost of electric vehicles participating in V2G when the cost of vehicle battery decline is considered. |
