The paper focuses on medium voltage grids characterised by a high level penetration of Distributed Energy Resources and examines the risks associated to the communication malfunctions of an ICT (Information and Communication Technologies) architecture implementing the voltage control function. The mostly critical segments of the communication infrastructure are clearly represented by the HV/MV substation networks that, in addition to local communications towards substation control devices and to information exchanges with the remote control centres, have to interact with external actors, managing distributed generators and controllable MV loads, and with MV/LV substations aggregating controllable small size generators and flexible LV loads.

The first step of the risk analysis shows how the impact on the unsupplied power depends on the topology of the controlled grid, but also on the communication networks targeted by potential attacks. Going deeply into the threat analysis, the paper evaluates mis-behavioural models of voltage control communications while someone is maliciously acting through relevant networks.

The impact and threat likelihood values are evaluated over the five scale matrix and the resulting risk levels are mapped on the security requirements to be satisfied by the ICT architecture, providing references to the most relevant security solutions currently under standardisation.