  This paper extends the research regarding the determination of the feasible
operation region under the impact of electric vehicles. Thereby, the active and
reactive power flexibility potentials of EV for alternating current and direct
current bidirectional charging are limited in first instance by regulatory
guidelines. In this paper German regulatory guidelines are applied to depicture
the current state of the art for EV charging components. Under assumption of
bidirectional charging for EV, the corresponding flexibility polygon in the PQ
plane is derived. The impact on the FOR is then evaluated within the Cigr\'e
European medium voltage benchmark system. In a first step, the flexibility
potential of the system is determined for a load case as basis for the
comparison with different, realistic penetration levels of EV. DER are
considered to depict additional existing power flexibilities. In a second step,
the FOR and the corresponding limitations within the system are analyzed. Under
variation of the rated line current, the limiting utility constraints are
pointed out. The obtained results are the basis for more detailed
investigations regarding the potentials of bidirectional charging for an
intensified system operators cooperation. The used method presents a promising
approach to be used by the lower system operator as tool in the grid planning
process to estimate the possible power flexibilities that can be provided to a
higher system. Continuing, the potential for ancillary services provided by EV
is discussed, resulting in the derivation of future research aspects. Because
the accumulation of EV leads to higher grid utilization, which results in
quadratically increasing grid losses the closer the grid is operating to the
grid constraints, a cost curve for the EVs active power flexibility is
introduced, whereas probability zones are indicated.
