Scheduling of electrical vehicle charging for a charging facility with single charger

Abstract

This paper proposes an algorithm to develop an optimum Electric Vehicle (EV) charging schedule for a charging facility with a single charger. Although there are many researches to address the developing of an optimum schedule for EV charging, current methods do not address this problem from the charging facility owner's perspective. We use a hybrid system framework to capture the tradeoff between demand charges proportional to the peak demand and speed of charging. However, this hybrid framework leads to a nonconvex and non-differentiable problem. This challenge is overcome by decomposing the problem into multiple smaller and simpler constrained convex optimization problems. With the resulting convex model proposed here, the minimum cost day ahead EV charging schedule can be determined from the charging facility owner's perspective. By using this tool, a day ahead, charging facility owner has the ability to set up prices based on the cost and customer has the ability to know the prices, the total waiting and the charging time at the charging facility. The nonlinear cost optimization model was developed by using a backward recursive algorithm. The proposed algorithm has been analyzed for different penalty factors which were imposed on total waiting time of each EV. Final results are analyzed and discussed.