A method to determine maximum number of available EV fast chargers under voltage constraints of distribution networks

This paper proposes a novel method for the management of EV fast charging stations from the viewpoint of voltage quality in distribution networks. In the future, EV's coincident charging possibly impacts on voltage profiles of distribution networks. The proposed method determines how many EVs can be charged by EV fast chargers with fast charging stations on distribution networks under constraints of voltage fluctuation. The proposed method is based on a solution of the linear programming (LP) with an objective function of maximizing the number of available fast chargers and constraints of linearized power flow equations. The proposed method can improve calculation precision of the number of available fast chargers by repeating modification of the linearized power flow equations with AC power flow and recalculation of the linear programming problem. In addition, the proposed method can be applied to PV connected distribution networks and easily estimate the reactive power required for the increase of the available fast chargers by using duality of LP. As a result, the proposed method can determine the maximum number of available fast chargers while keeping voltage profiles within the regulated range.