The Coordinated Charging Optimization For Electric Vehicles Based On Time-of-use Price

The development of electric vehicles(EVs) is not only to reduce the emissions of harmful, greenhouse gas and the dependence on imported oil, but also to solve the current fog and haze achieving clean, environmentally and friendly use of energy. However, there will be a negative impact on the grid for the uncoordinated charging of large-scale EVs. So it is necessary for us to study the coordinated charging optimization strategies for improving the existing grid utilization and carrying capacity.This paper has firstly investigated the research status of the coordinated charging optimization for EVs. And then the short-charging load has been forecasted. Finally, the four kinds of coordinated charging optimization strategies are proposed for different scenarios, different charging needs of users and the impact on the grid.Strategy One: For an EV taking home charging personally, a coordinated charging and discharging control strategy is proposed including the incentive factor of time-of-use price(TOU). According to the constraints of the power and the electricity price of charging and discharging provided the superior system, the linear model is proposed to minimize the fee of the total expenditure for EV's user by optimizing the charging and discharging power each time. The simplex method is applicated to obtain the optimal solution that is an economical scheme for EV's user.Strategy Two: For many EVs' coordinating charging, four kinds of optimization ways are proposed for the proportional power distribution, priority power allocation, overall process optimization and superior orders track based on the different decision-making body of the charging and discharging process. The linear programming and the heuristic algorithm are applicated to meet the different types of user's charging need.Strategy Three: For the charging station in the residential area, this paper proposes two kinds of EVs' coordinated charging modes that is the on-off charging mode automatically and the charging mode of the smooth adjustment. The coordinated charging optimization model is proposed to maximize the charging energy combined with Monte-Carlo simulation and improved particle swarm optimization(IPSO), on the basis of the existing distribution network of the residential area. It is calculated and compared with the different modes of parameter characteristics and indicators. According to the current TOU division principle, the concept of the saving cost is proposed to give the users the cost compensation for participating in the coordinated charging.Strategy Four: For the charging of EVs in multiple charging stations, a coordinated charging optimization is investigated. The charging demand boundaries are computed by each charging station based on the information of aggregate charging demand, and are sent to centralized controller at the distribution system for centralized coordination. The centralized controller then calculates the referential charging load profile for each charging station based on the TOU charging price. The simple linear programming is applicated by the centralized controller, and a simple heuristic algorithm is applicated by the each charging station, achieving the coordination charging control of the city-station level.Considering to the participants on the grid, charging stations, charging users that have the characteristics of their own needs, this paper is the overall coordination optimization for the EVs' charging systems. The proposed strategies can provide for building the system architecture and information exchange platform of three operations management for the province, city, station as reference.