Technical assessment of dispersed electric vehicles in medium voltage distribution grids

A large scale integration of electric vehicles as battery storage devices could be a new alternative to reduce contrary effects on electricity grids by volatile power generation. Mobile storage systems provide fast-response assistance that can be called on a short notice (within ms) and are therefore well suited to counteract fault conditions. Hence, the overall result could be an increased stability and reliability of the electric grid. However, it is not yet fully understood which scale of widely dispersed storage devices could provide efficient ancillary services without stressing the grid or increasing the cost for upgrading of existing infrastructure. Therefore, a first estimation of remaining grid capacity to integrate electric vehicles has been conducted. The fundamentals of probabilistic analysis serve a base to analyse and determine the stochastic behaviour of energy consumption of conventional loads e.g. households at distribution level superimposed by the behaviour of electric vehicles whilst charging. In order to assess the additional consumption of electric vehicles, typical driver behaviour has been analysed as well as the state of the art of battery technologies. Hence, the need of energy in conjunction with the rated power of battery chargers serve as input for grid assessment.