A New Two-Stage Approach to Coordinate Electrical Vehicles for Satisfaction of Grid and Customer Requirements

Abstract

Recently due to air pollution concerns, a large number of electric vehicles have been integrated into the electric distribution system. However, the uncoordinated charging of this technology can cause different voltage issues. This paper proposes a two-stage optimization approach with active and reactive power control to coordinate electric vehicles with both grid-to-vehicle and vehicle-to-grid capabilities to satisfy both grid requirements and electric vehicle prosumer requirements. The system requirements considered are voltage deviation and unbalance and the electric vehicle prosumer requirements considered are minimization of charging and battery degradation costs. The coordination problem is formulated as an optimization problem, where the first stage objectives are: minimization of voltage unbalance, customer charging and battery degradation costs. The first stage optimization problem is solved using the meta-heuristic optimization algorithm known as particle swarm optimization to obtain an optimized real power schedule for the electric vehicles. The second stage is then solved of which the objective is to minimize the bus voltage deviation and provides the reactive power schedule for electric vehicles. All the analyses were carried out on the IEEE 34 bus distribution system and the study results show that the proposed method allows prosumers to charge at a minimum cost without any grid voltage unbalance factors and under/over voltage problems under different scenarios. Thus, this work can be beneficial for system operators or electric vehicle aggregators to create a day-ahead schedule.

Smart charging of electric vehicles to minimize the cost of charging and the rate of transformer aging in a residential distribution network

“…The final energy can be computed by adding the initial energy at plug-in, E initial n with the total energy transferred subsequently as shown in (17). The final battery energy is constrained by (15) to prevent overcharging beyond rated capacity, E capacity n .…”

“…The energy losses in the system can be minimized by optimally scheduling the EV charging loads [12,13]. SC schemes that minimize voltage deviations in the network have also been developed [14,15]. In addition to these technical objectives, SC may also seek to minimize the utility's generation costs [16,17] or the EV owners' charging cost [18,19].…”

Electric Vehicle Cluster Scheduling Model for Distribution Systems Considering Reactive-Power Compensation of Charging Piles

“…Study [18] proposed a two-stage optimization method for energy loss minimization in microgrids based on a smart power management scheme for EVs. Study [19] presented a two-stage optimization approach for the active-and reactive-power control of EVs to meet both the grid and EV users' requirements. Although [15][16][17][18][19] have conducted in-depth studies on the modeling of EV participation in grid reactive-power optimization, this method does not take into account the charging preferences of the users, nor does it provide financial compensation to the EV users who participate in reactive-power compensation.…”

“…Study [19] presented a two-stage optimization approach for the active-and reactive-power control of EVs to meet both the grid and EV users' requirements. Although [15][16][17][18][19] have conducted in-depth studies on the modeling of EV participation in grid reactive-power optimization, this method does not take into account the charging preferences of the users, nor does it provide financial compensation to the EV users who participate in reactive-power compensation. In fact, EV users, as highly free individuals, can choose charging modes suitable for them according to their needs, such as fast charging, participation in charging optimization only, and participation in charging and discharging optimization.…”

The Local Ordered Charging Strategy of Electric Vehicles Based on Energy Routers under Three-Phase Balance of Residential Fields

“…Reference [17] analyzed the serious problems caused by disordered charging and studied the impact of electric vehicles on the three-phase imbalance of the distribution network under different penetration rates. Reference [18] proposed a novel unbalanced active distribution network electric vehicle orderly charging control strategy based on inverter's reactive power injection and three-phase selection, which realized the optimization of the grid's operation within 24 h. Reference [19] considered the three-phase imbalance of grid voltage and the cost of electric vehicle charging and battery aging, and proposed a two-stage optimization method based on active power and reactive power control to meet the needs of electric vehicle users and reduce the impact of the access of electric vehicles on the three-phase imbalance of the grid voltage. Reference [20] proposed a management method for photovoltaic electric vehicle charging stations, and divides this management method into three stages, taking into account the installation requirements of local stakeholders, the needs of users, and the configuration of users.…”