I. Introduction
Today almost all activities in our society rely on the electric power system. While computer, wireless communication, and many other aspects have dramatically changed our lives, the electric power system still operates based on the infrastructure that was designed decades ago. This aged system now becomes overloaded, especially during high-peak hours. Traditional power grid cannot predict the power demand efficiently. Therefore, it needs to use additional power sources, when the demand grows high. This solution is expensive and exacerbates pollution problem.