  This paper considers a bi-level discrete-time control framework with
real-time constraints, consisting of several local controllers and a central
controller. The objective is to bridge the gap between the online convex
optimization and real-time control literature by proposing an online control
algorithm with small dynamic regret, which is a natural performance criterion
in nonstationary environments related to real-time control problems. We
illustrate how the proposed algorithm can be applied to real-time control of
power setpoints in an electrical grid.
