Avoiding low-voltage grid overloads through curative grid operator intervention with focus on electric vehicles

Abstract

The increasing market penetration of electric vehicles in Germany challenges the low-voltage grid in the upcoming years. Besides conventional grid expansion, emerging congestions can be cured by using demand-side flexibility. One approach is the model of peak smoothing. This paper investigates the effects of a realisation. Therefore, the electricity grid model GridSim is extended. The effect of peak smoothing is analysed based on load flow calculations of 1,206 low-voltage grids. Future developments such as tariff-optimized (dis-)charging of bidirectional electric vehicles, known as vehicle-to-grid (V2G), are considered. The results show that the model of peak smoothing postpones but mostly does not avoid the need for grid expansion. Until the year 2040, 386 out of 1,206 grids must be expanded despite the application of peak smoothing. In most cases, this happens due to transformer overloads and voltage band violations. However, on the other hand, the model results in minor restrictions for customers, as an implementation only leads to grid operator interventions for a few hours a year. In addition, almost all the curtailed energy (> 97,8%) is recharged by the customers later. Due to the infrequent interventions, there is also little impact on the power forecast.