Research On Dispatch Of Coordination Between Electric Vehicles And Power Grid

Application of large-scale electric vehicles in the presence of high renewable energy penetration can be an efficient way to solve century problems including energy crisis, air pollution and high-speed growth of motor vehicles. However, the uncoordinated charging of numerous electric vehicles can produce significant negative impacts on the secure and economic operation of the power system concerned. Although a great mass of researches on dispatch of coordination between electric vehicles and power grid have been studied, there are still some further works deserve to make,this paper mainly focuses on the complement of coordination between battery swapping stations and power grid & coordination between electric vehicles and islanded microgrid, and obtains some correspondingly innovative research results:Firstly, considering the constraints of battery swapping station operation needs, model without objective is built based on analysis of the factors related to the power demand on electric vehicles charging, then further study is conducted on impact of uncoordinated charging of BSS from aspects of such as peak-valley ratio and systems losses, through numbers of batteries of BSS and state of capacity. At the same time, comparing traditional probability method, the results show difference between them is very close.Secondly, a new multi-objective bi-level optimization model of real-time charging/discharging dispatch with coordination of BSS and power grid is established. The upper-level model is devoted to minimizing system load variance and dispatching deviation of the two levels. The whole charging/discharging schemes of BSS are determined by upper-level dispatching central, while the lower-level model aims at following the dispatching instructions from the upper-level and satisfying the battery swapping needs of customers. Then, the large-scale mixed integer nonlinear programming problem is divided into a nonlinear multi-objective programming and a large-scale mixed integer linear programming problem. Two effective methods, NSGA-II based on Zaslavskii chaotic map and YALMIP/CPLEX respectively, are employed to solve the developed optimization problem. The results of simulations demonstrate the feasibility and efficiency of the proposed model.Finally, the hierarchical dispatching method of coordination between electric vehicle and islanded microgrid is proposed considering distributed generation units' statistical droop characteristics, the statistical coefficients of lower-level droop control are determined by the upper-level control, while the lower-level control adjusts power outputs according to droop characteristics real-timely to maintain stable microgrid operation. YALMIP+OPTIToolbox+IPOPT is employed to solve the hierarchical model, and results show it can be efficiently solve this complex security-constraint economical dispatch model for islanded microgrid without slack bus, and there is a significant advantage for dispatch method proposed in smoothing the uncoordinated charging power of electric vehicle, reducing cost of distributed generation operation and improving system voltage level, beside, even if a fault occurred in communication, power balance can still be guaranteed by lower-level decentralized droop control.