Grid compatible flexibility management with a Quota-based aggregator of electric vehicles using a split charging approach in residential grids

Abstract

This paper addresses the issue of high coincidence factors during electric vehicle (EV) charging cycles and the impact of flexibility aggregators. Based on findings for grid planning principles for EVs, an approach was explored to reduce grid loads caused by charging currents through the reduction of the probability of simultaneous charging cycles. Through the implementation of a split charging routine, which limited the first residential charge to a maximum state of charge, the corresponding reduction in charging duration translated into a reduced coincidence factor. Furthermore, the remaining charging capacity was made accessible as a flexible load for an aggregator. In order to prevent price-triggered high coincidences, these aggregators were integrated into the German "Grid Traffic Light" concept to allow for optimal load distribution. Here, based on the Quota System developed by the Netze BW, it was shown, that both markets and grid operators benefited from this approach.