The book chapter deals with the cyber security evaluation of active distribution grids characterized by a high level penetration of renewable Distributed Energy Resources (DER). This evolution of the energy infrastructure introduces significant changes in the control and communication functions needed for meeting the technical, security and quality requirements during the grid operation. The risk analysis and treatment of fully controllable smart grid energy infrastructures require effective evaluation tools and scalable security measures. The analysis focuses on a Voltage Control function in medium voltage grids addressing voltage stability of the power grid when a consistent amount of distributed renewable sources are connected.

For this reason the chapter analyses the most relevant security scenarios of an ICT (Information and Communication Technology) architecture implementing this control application. The risk levels resulting from the analysis are linked to security requirements and standard measures whose deployment in real scale infrastructures requires the security testing of application architectures. The chapter presents an experimental environment for the security testing and evaluation of voltage control communications. This includes the test bed set up, the test cases and the evaluation framework to be used for measuring the attack effects on communications and verifying the mitigation capability of standard security measures.