Day-ahead optimal charging/discharging scheduling for electric vehicles in micro-grids

A micro-grid is an autonomous system which can be operated while connected to an external system or isolated with the help of energy storage systems (ESSs). While the daily output of distributed generators (DGs) strongly depends on the temporal distribution of natural resources such as wind and solar, unregulated electric vehicle (EV) charging demand will reduce the imbalance between the daily load and generation curves. In this paper, a statistical model is presented to describe daily EV charging/discharging behaviour. An optimisation problem is proposed and verified to obtain economic operation for the micro-grid based on this model. In day-ahead scheduling, with estimated information of power generation and load demand, optimal charging/discharging of EVs during 24 hours is obtained. A series of numerical optimisation solutions, in different scenarios, is achieved by serial quadratic programming. The results show that with optimal charging/discharging of EVs network losses can be decreased.