Implementation of different intelligent controllers for mitigating the AC corrosion of metallic pipelines considering all HVOHTLs operation conditions.

AC corrosion represents a chronic issue that is faced by the buried metallic pipelines that are neighboring by the high voltage overhead transmission lines (HVOHTLs). In this paper a potassium hydroxide polarization cell (KOH-PC) is employed on the pipeline to mitigate the generated voltage from the power lines' intrusion with the buried pipeline. This work further investigates an integrated system to exploit the discharged energy for compensating the cathodic protection disturbances where a portion of this energy may be converted to DC form and reapplied on the pipeline as a cathodic protection voltage. This paper also presents a comparative analysis of different KOH-PCs' models with different controllers to provide the guidelines for deciding which one of these techniques is more suitable for mitigating the induced voltage and improving the cathodic protection distribution during normal and fault operating conditions of transmission lines. The applied controllers are the artificial-neural-network (ANN), Fuzzy-logic-controller (FLC), and​ adaptive-neuro-fuzzy inference system (ANFIS). The proposed model's performance is implemented through modeling and simulating on MATLAB software with the experimental measurements from the comparative analysis. The ANFIS controller is more precise in differentiation with other controllers in compensating for the CP disturbances.

Modeling of the KOH-Polarization cells for mitigating the induced AC voltage in the metallic pipelines.

The problem of AC corrosion remains motivating for researchers because many factors influence the corrosion rate for buried pipelines due to the interference with overhead high voltage transmission lines (OHVTLs). Many researchers study the mechanisms of induced alternating current (AC) voltages, which are summarized as capacitive, inductive, and conductive coupling. In this work, only the induced AC voltage on the pipelines due to inductive coupling in steady-state conditions is studied. A holistic mathematical model for the pipelines, power lines, mitigation equipment for the induced voltage, and cathodic protection (CP) is illustrated. Potassium hydroxide polarization cells are electrically represented because these cells are considered the most common mitigation device for discharging the induced AC voltage from the pipeline to the soil. The overall model is implemented using MATLAB. The results show the profiles of induced AC voltage along the pipeline, the CP for the pipeline, the points of maximum voltage, and the influence of installing the AC mitigation units on the CP performance.