Demand Management in off-Grid 100% Renewable Energy Microgrid Integrated with Electric Vehicle Charging Station based on Battery Swapping

In this paper an off-grid microgrid, based on 100% renewable energy, integrated with an electric vehicle charging station, an electric vehicle parking station, and a demand-response program was modeled. The electric vehicle charging station operated based on a battery swapping model in order to charge the electric vehicles in the shortest time possible. The electric vehicle parking station was used to park vehicles during various hours of the 24-hour period. The vehicles inside the parking had to be fully charged by the microgrid when leaving the parking station. Since these vehicles were parked for several hours, their charging time was not limited, and they are charged by direct chargers rather than battery swapping. The loads of the microgrid were under a demand-response program, and they were curtailable, non-curtailable, shiftable, and interruptible loads. The only energy source of microgrid was solar PV systems; the solar-energy related issues such as zero energy during night, output power variations, and the possibility of losing the whole or a part of energy due to shade should be dealt with. In the proposed method, an optimal programming was applied to the charging-discharging of the swapping batteries in charging station, to the charging-discharging of electric vehicles in the parking station, and to the energy management of loads (i.e., curtailable, non-curtailable, shiftable, and interruptible loads). The mismatch of energy and the lack of solar energy were compensated by the discharging power from charging and parking stations as well as by the management of the power of loads. Simulation results demonstrated that the unavailability of solar energy during the night resulted in paying 50% of the daily revenue as penalty cost. During hours such as 7 to 19, when the solar energy was available, the plan used the solar power as much as possible and limited the extracted energy from other energy resources. The energy of shiftable loads was supplied mostly from 13 to 15 hours, when solar energy was at the maximum level.