MPC-based Voltage Control with Reactive Power from High-Power Charging Stations for EVs

The recent development of EVs with high-capacity batteries and high charging power capabilities leads to an increased demand for fast-charging stations (FCS). However, FCS can cause power quality issues such as voltage drops in distribution grids with limited power capacity. Grid reinforcements are a standard solution for solving power quality issues. However, these can be costly. An alternative approach is to install bi-directional chargers at FCS and use this flexibility source to provide voltage support in peak-load periods by injecting reactive power to the grid. This paper proposes a model predictive controller (MPC) to control and coordinate such high-power chargers. The MPC maximizes the charging rate for the EVs while ensuring that the voltage level stays within the allowable limits. The control system has been evaluated through simulations on a realistic grid model, and the results show that both the FCS and the grid can benefit from utilizing the reactive power.