A Novel Approach to Design Cathodic Protection System for High-Voltage Transmission Cables

Corrosion is an electrochemical process involving electrical currents. It consists of the destruction of a metal through its interaction with the environment. The phenomenon is observed in underground and buried structures, where aging can be strongly influenced by electrical currents flowing in the Earth. Methods of protection (i.e., “cathodic protection”) are related to the use of sacrificial anodes or more sophisticated systems, which impose a negative voltage to the metal structures to be protected. The corrosion phenomenon can be relevant also in electric power system applications. Underground or undersea electrical cables need to be protected as a consequence of stray currents flowing in the soil. This paper studies the problem of cathodic protection design for high-voltage transmission cables in undersea applications. The aim is to propose a design procedure which can be implemented by nonexpert electrical designers. A practical approach, which characterizes the distribution of the voltage on the outer layer of power cables, is formalized on the basis of common simplified assumptions. Numerical simulations give evidence to the formulation according to the features of environmental conditions.