  Plug-In Electric Vehicles (PEV) have become a key factor driving towards
smart cities, which allow for higher energy efficiency and lower environmental
impact across urban sectors. Industry vision for future PEV includes the
ability to recharge a vehicle at a speed comparable to traditional gas
refueling, i.e., less than $3$ minutes per vehicle. Such a technology, referred
to as Ultra-Fast Charging (UFC), has drawn much interest from research and
industry. The large power density, impulsive, and stochastic loading
characteristics of UFC, however, pose unprecedented challenges to existing
electricity supply infrastructure. Planning the locations and electric
capacities of these UFC stations is critical to preventing detrimental impacts,
including grid asset depreciation, grid instabilities, and deteriorated power
quality. In this paper, we first review planning methods for conventional
charging stations and then discuss outlooks for UFC planning solutions by
drawing an analogy with renewable energy source planning, which presents
similar power density and stochastic characteristics as UFC. While this paper
mainly focuses on UFC planning from the power grid perspective, other urban
aspects, including traffic flow and end-user behavior, are examined for
feasible UFC integration within smart cities.
