Economical Charging Strategy Of Electric Vehicle Based On Game Theory

The restricted interaction relationship of energy and environment have been paid attention by human beings for a long time and become a key problem to be solved.The emergence of plug-in electric vehicle(PEV)relieved the utilization of fossil fuel,which at the same time reduced the corresponding emission of carbon dioxide and other vehicle exhaust,as a consequence,have been striking increasingly.In the future smart grid,the PEV will play an important role,but will bring lots of economical and safe issues to grid as the quantity is growing to an enormous number.This paper mainly focus on the economical issues caused by the charging behavior of PEV in two charging modes which will affect the power grid in different ways.First,we briefly introduce the basic concept of game theory and some pivotal properties of Nash equilibrium,and the main computation methods are summarized as well;moreover,the effectiveness and availability of the access of game theory to the perspective of coordinative optimization of multi-decision makers in the future smart distribution grid as a powerful tool are analyzed.Then,the economics problem at slow charging pattern is discussed.This charging mode will be widely used in the future smart residential district where the PEV could be plugged in through the intelligent agent in the smart grid.This paper model this charging pattern as a PEV demand response(DR)problem and is solved by a noncooperative game theoretical framework.The charging behavior of PEV is adjusted by the real-time electric price model,which means the PEV have to make the rational choice to transfer the charging time to the valley load section in case of the high charging fee during the peak load section.So that the total load curve could be regulated to the form of peak load shaving and valley load filling.And when the Nash equilibrium reached,no player would change his strategy unilaterally due to the cost has been minimized.At last,the PEV load spatial distribution problem at fast charging pattern is discussed.This charging mode could be applied to the city fast charging station for the high charging rate which could meet the emergency demand of heavy traffic situation.This paper propose a two-level game analytical method to handle the spatial distribution of PEV toward charging station in a city.At the lower level,a evolutionary game theory is performed to simulate the dynamic charging station selection process of PEVs according to the charging price and estimated waiting time broadcasted by the charging station,and with the introduction of replicator dynamics,the PEV will continuously evolve its strategy based on the difference between the current payoff and that of average.When the evolutionary equilibrium at the lower level is reached,the charging stations at upper level play the noncooperative game by changing the charging price to appeal to the PEV for maximizing their revenue independently,which is the key to implement the interaction of two level games.When the Nash equilibrium is finally reached at the upper level: as the perspective of economics,the payoff of both the PEVs and the charging stations would be maximized,and the payoff of each PEV will be equal to the average payoff of the PEV population.