Secure communication interface for line current differential protection over Ethernet-based networks

We consider a line current differential protection (LCDP) system, where the protective relays communicate via Ethernet-based networks. In correct function, LCDP devices switch off the protected power line in case of a fault. Since such a switching may immensely effect the entire power grid, the communication line between the protective relays is an attractive target to attack power grids. For LCDP systems, we identify the measurement exchange and the channel based clock synchronization as vulnerable components, for which we introduce threat models and a security concept. More specifically, we use IPsec to protect the communication and a newly introduced algorithm to detect delay attacks. Only the combination of both ensures secure operation of LCDP, which is shown in real measurements.