Power-line communications (PLC) have enabled many smart grid applications over the past years. Secure communications over such channels, however, remains a crucial aspect for the successful realization of smart grids. Many techniques have been proposed in the literature to achieve this and the most recent of which is the adoption of physical layer security for PLC systems. Unlike the existing work, in this paper, we investigate physical layer security of cooperative relaying PLC systems with artificial noise in the presence of an eavesdropper. The system performance is evaluated in terms of the average secrecy capacity. In light of this, we derive a mathematical expression for the average secrecy capacity and validate it with Monte Carlo simulations. Results reveal that the proposed system can significantly enhance the security of PLC systems.
