  The dominance of distributed energy resources in microgrids and the
associated weather dependency require flexible protection. They include devices
capable of adapting their protective settings as a reaction to (potential)
changes in system state. Communication technologies have a key role in this
system since the reactions of the adaptive devices shall be coordinated. This
coordination imposes strict requirements: communications must be available and
ultra-reliable with bounded latency in the order of milliseconds. This paper
reviews the state-of-the-art in the field and provides a thorough analysis of
the main related communication technologies and optimization techniques. We
also present our perspective on the future of communication deployments in
microgrids, indicating the viability of 5G wireless systems and
multi-connectivity to enable adaptive protection.
