The Influence of Smart Charging and V2G on the Flexibility Potential and Grid Expansion Needs of German Distribution Grids

This paper investigates the potential of smart charging and vehicle to grid (V2G) to reduce the stress on German distribution grids. Therefore, two optimised and a reference charging strategy are evaluated with respect to their potential to reduce the necessary curtailment and grid reinforcement. Furthermore, the flexibility potential in terms of energy shifting is evaluated. The first optimised strategy, constrained charging, allows to shift charging demand only within standing times. The second optimised strategy, unconstrained charging, allows to shift charging demand over different charging events and to provide V2G service. The reference strategy simulates uncoordinated charging. Both of the optimised charging strategies successfully reduce the necessary curtailment by shifting the charging demand to times of high feed-in and lower component loading. Especially the curtailment of the load is significantly reduced by optimised charging, whereas the impact on the curtailment of feed-in is limited. The grid expansion costs are reduced by optimised charging, and peaks can be lowered. However, the additional gain from unconstrained optimised charging is significantly smaller than the benefit from constrained optimised compared to reference charging. The available flexible energy, on the other hand, increases by a factor of about nine with unconstrained charging compared to constrained charging. The added value therefore highly depends on the use case.