Scenario tree generation for the optimization model of a parking lot for electric vehicles

This paper deals with a procedure capable to build the scenario tree associated with a parking lot equipped with several bidirectional charging stations for plug-in electric vehicles (EVs). The scenario tree is conceived to be implemented in multistage stochastic optimization models for day-ahead energy management systems of microgrids or, more in general, power distribution networks. Specific operating rules relevant to the initial energy available in the cars entering the parking lot are defined, as well as the other typical constraints (such as maximum number of available charging stations, size of the EVs batteries, and power ratings of charging stations). Moreover, the model reproduces also the coupling between the operation of the parking lot with the power production of a photovoltaic unit. The tree generation procedure at first generates a number of equiprobable scenarios by using day-ahead forecasts and the probability distributions characterizing the expected deviations with respect to the forecasts; then similar scenarios are grouped on the basis of the chosen criteria and of the number of stages. A specific procedure is finally proposed and applied in order to guarantee the existence of feasible solutions.