  Electrochemical energy storage (ES) units (e.g. batteries) have been
field-validated as an efficient back-up resource that enhance resilience of the
distribution system in case of natural disasters. However, using these units
for resilience is not sufficient to economically justify their installation
and, therefore, these units are often installed in locations where they incur
the greatest economic value during normal operations. Motivated by the recent
progress in transportable ES technologies, i.e. ES units can be moved using
public transportation routes, this paper proposes to use this spatial
flexibility to bridge the gap between the economically optimal locations during
normal operations and disaster-specific locations where extra back-up capacity
is necessary. We propose a two-stage optimization model that optimizes
investments in mobile ES units in the first stage and can re-route the
installed mobile ES units in the second stage to avoid the expected load
shedding caused by disaster forecasts. Since the proposed model cannot be
solved efficiently with off-the-shelf solvers, even for relatively small
instances, we apply a progressive hedging algorithm. The proposed model and
progressive hedging algorithm are tested through two illustrative examples on a
15-bus radial distribution test system.
