Studies On Optimal Charging Station Placing And Orderly Charging Strategy For Large-Scale Electric Vehiclesinto Grid

The electric vehicle is a kind of clean energy transport which can effectively reduce noise pollution, greenhouse gases and harmful emissions and fossil energy consumption. In recent years,with the expansion of the power system, the continuous improvement of battery technology and the deterioration of environmental pollution and energy shortage, electric vehicles get attention and rapid development all over the world. From the relevant development plan conducted by governments and manufacturers, the market share of electric vehicles in the near future will reach a higher level. However, as a kind of random high-powerelectric loads, the large-scale expansion of electric vehicleswill generate a huge gap of charging infrastructure construction on the one hand, and will pose a threat to safe and economic operation of the power grid on the other hand. Based on the large-scale expansion of electric vehicles in the future, this paper sdutied in detail two issues, namelythe optimal layout of charging stations and orderly charging strategy. The main outputs of this paper are displayed as follows:Aimed at the problem of an poor use of battery capacity utilization among the existing charging load model, this paper presents a modeling strategy of charging loads due to large-scale electric vehicles considering multi-days spaced charging mode. The strategydivides out six user sets according to users’daily travel distance, and proposes a calculation method of the load expectation of a single user set in specified time instant on the basis of a detailed analysis on the probability characteristics of charging start time and charging duration of a single electric vehicle from each user set. Then proposes the load calculation model and its discrete approach of the aggregated charging load on each workday based on the Law of Large Numbers. In addition, this paper puts forward the concept of initial date window, and simulates the probability distribution of uses over workdays under two kinds of multi-days spaced charging moderespectively.Aimed at the problem of an excessive use of subjective assumptionson the candidate station site positioning among the existing optimal placement strategies of charging stations, this paper proposes a strategy to optimize the layout of the site location analysis based on positioning analyses of candidate station sites. The strategy demonstrates the best station site on a single road based on P-median theory, and proposes individually analysis method and overall analysis method respectively for the road without and with charging demand points, and then obtains the candidate site set of a region to be planned. On this basis, within the searching scope of determined candidate sites, establishes a charging station layout optimization model aimed at minimizing the total charging reach cost of all charging demand points in a region to planned. Aimed at the problem of an inadequate consideration and application of newly generated charging requests insubsequent periods, this paperproposesan ordered charging strategy accounting the compensation of predicted charging requestsfor the residential charging behaviors. At the end of each control periods evenly divided, the strategy corrects the predicted results of newly generated charging request of the current control time period, which is conducted in the former control time periods, and utilizes the predicted charging requests to compensate the newly added electric vehicles waiting for charging in each control time periods following the current control time period, which improves the application effect of predicted results of charging requests effectively. On this basis, the paper establishes an ordered charging control model aimed at minimizing the load fluctuations.Aimed at the problem of insufficient mining of electric vehicle storage advantage, this paper proposes a residential ordered charging strategy based on extended time scale, which considers the multi-day spaced charging mode as an inherent charge mode of a part of users.This paper analyzes in detail the charging behavior characteristics of the individual user and user groups over extended time scale, and proposes a calculation method of the value range of users’ charging start time over extended time scale. On these bases, a charging optimal model aimed at minimizing the peak-valley difference of system load under extended time scale is established.