I. Introduction
The future electric power generation and supply system, which is recognised as the smart grids, is expected to bring significant benefits to energy generation and dispatch. The direction of power flow will no longer be just downhill from the bulk power plants to consumers. Power flow can be generated from any energy generation sources and end up anywhere on the grid. As micro level local energy generation such as rooftop solar cells, electricity can be generated and stored by consumers and can be released to the grid whenever it is necessary [1]. Electric vehicles (EVs) have been generally expected to be a main component of distributed energy storage and supply device in the smart grids. EVs can serve as a distributed mobile energy resource in the electricity market. Enabled by the advanced information and communications technologies (ICTs), EVs can be optimally scheduled and dispatched to various locations at different times to supply energy to meet the dynamic demand and fast response to emergency situations [2]. EVs can also be used to store and transport energy from one geographical area to another as supportive supply, which will increase the overall reliability and the flexibility of the grid [3]. As EVs will eventually be employed at the household level as alternatives of traditional petrol cars, EVs sohuld be included in home electricity demand management and consumption optimization, as discussed in [4] and [5].