A Distributed Optimization Model for Mitigating Three-phase Power Imbalance with Electric Vehicles and Grid Battery

Abstract

Three-phase power imbalances may occur in the distribution network due to high electric vehicle (EV) charging demand. The imbalances become severe with the increasing number of EVs in the future and may be addressed with coordinated charging strategies. In this paper, we propose a phase-balancing and peak-shaving scheme for a community in the three-phase power distribution system by managing the charging and discharging strategies for EVs and grid battery energy storage systems (BESS). The proposed scheme includes energy transactions and distributed optimization models. In the transaction model, vehicle-to-vehicle (V2V) energy trading is considered. In the optimization model, the distribution system operator (DSO) optimizes the energy management strategy of the grid BESS while the EV owners optimize their charging strategies. Financial incentives are introduced to encourage the EV owners to assist the distribution system operator in reducing the phase imbalance. Simulation results show that the proposed scheme could mitigate the phase imbalance and reduce the difference between peak and valley load of the load curves in the three-phase distribution system. Both EV owners and the distribution system benefit financially. Moreover, the power quality and system reliability of the distribution network can also be improved.