  Large-scale integration of plug-in electric vehicles (PEV) in power systems
can cause severe issues to the existing distribution system, such as branch
congestions and significant voltage drops. As a consequence, smart charging
strategies are crucial for the secure and reliable operation of the power
system. This paper tries to achieve high penetration level of PEVs with the
existing distribution system infrastructure by proposing a smart charging
algorithm that can optimally utilize the distribution system capacity.
Specifically, the paper proposes a max-weight PEV dispatch algorithm to control
the PEV charging rates, subject to power system physical limits. The proposed
max-weight PEV dispatch algorithm is proved to be throughput optimal under very
mild assumptions on the stochastic dynamics in the system. This suggests that
the costly distribution system infrastructure upgrade can be avoided, or
failing that, at least successfully deferred. The proposed PEV dispatch
algorithm is particularly attractive in integrating the renewable energy
sources in the distribution system, by successfully absorbing their
intermittency.
