A market regulator is considered to increase the market efficiency and hence several regulations are tried to achieve this target. In many of such regulations, special conditions of renewable energies have been introduced. Accordingly, it is observed that some changes in regulations may have indirect undesirable effects on involved companies. In this paper, effects of the changes in market regulations on the behavior of both plug-in electric vehicle owners and their aggregators have been studied. A hybrid method is proposed to simulate the behavior of the market players from both regulator and aggregator's point of views. In addition, behavior of electric vehicle owners has been modeled considering type of the contract with aggregator. The result shows that a clever aggregator can convert some threats to changes in market regulations and there have been opportunities to increase the profit, enhanced the costumers and even the market efficiency. (C) 2012 Elsevier Ltd. All rights reserved.