Day-ahead tariffs for the alleviation of distribution grid congestion from electric vehicles

An economically efficient day-ahead tariff (DT) is proposed with the purpose of preventing distribution grid congestion resulting from electric vehicle (EV) charging scheduled on a day-ahead basis. The DT concept developed herein is derived from the locational marginal price (LMP), in particular the congestion cost component of the LMP. A step-wise congestion management structure has been developed whereby the distribution system operator (DSO) predicts congestion for the coming day and publishes DTs prior to the clearing of the day-ahead market. EV fleet operators (FOs) optimize their EV charging schedules with respect to the predicted day-ahead prices and the published DTs, thereby avoiding congestion while still minimizing the charging cost. A Danish 400 V distribution network is used to conduct case studies to illustrate the effectiveness of the developed concept for the prevention of distribution grid congestion from EV charging. The case study results show that the concept is successful in a number of situations, most notably a predicted system overload of 155% can be successfully alleviated on the test distribution network.

► A day-ahead grid tariff scheme is developed to alleviate congestions from EVs.
► Locational marginal prices (LMPs) are used to determine dynamic grid tariff.
► EV charging schedules are determined according to spot prices and grid tariffs.
► The linear programming method is used to determine the optimal EV schedules.