  Accurately evaluating the real-time flexibility of electric vehicles (EVs) is
necessary for EV aggregators to offer ancillary services. However,
regulation-caused uncertain state-of-charge and random departure behavior
complicate the evaluation and badly impact the evaluation accuracy. To resolve
this issue, this letter proposes a distributionally robust real-time
flexibility evaluation model that formulates the uncertain departure behavior
and state-of-charge of EVs in an online updating pattern. Thanks to
dualization, this model can be efficiently solved via off-the-shelf solvers.
Case studies validate the superiority of the proposed method and its
scalability regarding EV numbers.
