An Energy Management Strategy for a DC Distribution System for Power System Integration of Plug-In Electric Vehicles

This paper proposes an energy management strategy (EMS) for a dc distribution system for power system integration of plug-in electric vehicles (PEVs). The dc distribution system is intended to integrate electric vehicles in a parking lot with an ac grid through bidirectional dc-dc converters (battery chargers) and a central voltage-sourced converter. Using an online constrained optimization algorithm, the proposed EMS manages the power flow within the dc system. Thus, the PEV owners can charge or discharge their batteries based on the state-of-charge of the batteries and their upcoming trip plans. The EMS offers two energy exchange options to the PEV owners: 1) the fast energy exchange option for the owners wishing to minimize the energy exchange time; and 2) the optimal energy exchange option for the owners intend to either minimize their costs of charging or maximize their revenues through selling their stored energy. The proposed EMS seamlessly handles all charging/discharging requests from the PEV owners with different options and, at the same time, it takes into account the power demand and power generation limits of the ac grid to preclude under-voltage, over-voltage, and reverse power flow issues. Various energy exchange scenarios are simulated to demonstrate the effectiveness of the proposed EMS.