Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics ADNAN MUJEZINOVIĆ, IRFAN TURKOVIĆ, ALIJA MUHAREMOVIĆ Faculty of Electrical Engineering University of Sarajevo Zmaja od Bosne bb, Sarajevo BOSNIA AND HERZEGOVINA SANJA MARTINEZ Faculty of Chemical Engineering and Technology University of Zagreb Trg Marka Marulića 19, Zagreb CROATIA SLOBODAN MILOJKOVIĆ Faculty of Electrical Engineering University of East Sarajevo BOSNIA AND HERZEGOVINA Abstract: - Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples. Key-Words: - Boundary Element Method, Finite Difference Time Domain Method, Newton-Raphson Technique, Nonlinear Systems Received: February 16, 2019. Revised: April 2, 2020. Accepted: April 18, 2020. Published: April 30, 2020. 1 Introduction Cathodic protection is most widely used technique for protection of the underground and underwater metallic structures from corrosion [1]. This technique is based on the shifting the equilibrium potential of protected structure to more negative value. This can be done by connecting the protected object with additional electrode(s) placed in same electrolyte (ground or water), which equilibrium potential is more negative than equilibrium potential of the protected object [2]. After installation of the cathodic protection system, electric potential value on the entire surface of protected structure must be lower than minimum protection potential value defined by standards [3]. Also, current density distribution on the surface of protected structure WSEAS TRANSACTIONS on MATHEMATICS DOI: 10.37394/23206.2020.19.15 Adnan Mujezinović, Irfan Turković, Alija Muharemović, Sanja Martinez, Slobodan Milojković E-ISSN: 2224-2880 154 Volume 19, 2020