  The increase of electric demand and the progressive integration of renewable
sources threatens the stability of the power grid. To solve this issue, several
methods have been proposed to control the demand side instead of increasing the
spinning reserve on the supply side. Here we focus on dynamic demand control
(DDC), a method in which appliances can delay its scheduled operation if the
electric frequency is outside a suitable range. We have recently shown that DDC
effectively reduces small and medium-size frequency fluctuations but, due to
the need of recovering pending tasks, the probability of large demand peaks,
and hence large frequency fluctuations, may actually increase. Although these
events are very rare they can potentially trigger a failure of the system and
therefore strategies to avoid them have to be addressed. In this work, we
introduce a new method including communication among DDC devices belonging to a
given group, such that they can coordinate opposite actions to keep the group
demand more stable. We show that for this method the amount of pending tasks
decreases by a factor 10 while large frequency fluctuations are significantly
reduced or even completely avoided.
