Online Speeding Optimal Charging Algorithm for electric vehicles without future information

The integration of massive plug-in electric vehicles (EVs) to the power grid requires the charging to be coordinated to minimize the energy cost. The difficulty of an efficient charging control mainly comes from the uncertainty of each EV's charging profile. In this paper, we propose an online Speeding Optimal Charging Algorithm (SOCA), which does not rely on any knowledge of the future information. In particular, we show that SOCA ensures finishing charging all EVs and achieves the best known competitive ratio (2.39). It guarantees the worst-case performance regardless of the EVs' charging profiles. Through extensive simulations, we show that on average SOCA results in less than 14% extra cost of the optimal offline algorithm. By setting proper speeding factor, SOCA can further reduce the extra cost to less than 6%.