Optimal charging strategy of electric vehicles customers in a smart electrical car park

A smart electrical car park with electric vehicles (EVs) parking there, regarded as a short-term storage system, could minimize the costs of EV customers and improve the main grid stability simultaneously. This system, including numerous bidirectional AC/DC converters, a local energy storage unit and a monitoring room, is firstly established. As the hourly prices of electricity fluctuating with time, EV owners would like to charge energy from the main grid during the low-price periods to save money, while discharging energy to the main grid during high-price periods. In order to achieve this, an optimal charging scheme is proposed to determine the charging rate of each EV based on the fluctuation of hourly prices and requirements of customers. Thus, this charging/discharging strategy can reduce the costs for EV owners and help keep the balance of supply and demand for the main grid. A comparison between the cost of EVs customers with and without the developed smart charging/discharging strategy in this smart electrical car park is presented and analysed in Matlab with an optimization problem solver named Cplex in this study. It is demonstrated that the proposed charging/discharging strategy can not only reduce EV owner's cost but also improve the main grid stability as well.