Flexible Operation of an EV Parking Lot for Voltage Control of a Distribution Network

The paper presents an optimization model for the voltage control in a distribution network, which exploits the flexibility provided by parking lots equipped with several electric vehicle (EV) charging stations. The optimization process is performed through the definition of an objective function given by the sum of deviations of node voltages with respect to the ref-erence value, subject to the linearized set of DistFlow equations. The problem is solved according to a centralized approach by the definition of voltage control zones. To provide an ancillary service to the network, the EV aggregator of the charging stations in the parking lot can vary the intra-day scheduling inside the flexibility margins calculated so to guarantee the appropriate EV charging level by using a stochastic optimization approach. The paper illustrates the results for different case studies based on the IEEE-123 node Test Feeder. The results demonstrate the efficacy of utilizing flexibility services in optimizing the voltage profile.