Integration of plug-in electric vehicles in power systems using charging mode switching

In this paper, we develop an energy management algorithm for charging and discharging plug-in electric vehicles (PEVs). The algorithm considers both user convenience and electricity market factors. A performance metric, called 'user convenience', is formulated to measure the effective coordination of PEV charging. As a response to the electricity market, we address an economic dispatch problem by considering power flows, grid losses, voltage profile patterns, and vehicle-to-grid costs. Both of the concerned factors can be optimized by simply switching a PEV during charging, discharging, or in off-mode. The mode switch allows easy integrate of PEVs into power systems. The PEV state-decision problem can be efficiently solved by using convex optimization tools. Moreover, the problem can be solved in a decentralized manner, wherein each sub-aggregator can determine to charge, discharge, and turn to off-mode locally. Simulation results indicate that the proposed PEV energy management algorithm can obtain the same final state-of-charge of the batteries as those obtained by unconstraint cases. Meanwhile, the effect of PEV charging on the power system is significantly mitigated.