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

Abstract

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.

Different Polarization Cells Based for Mitigating theAC Induced Voltages on the Metallic Pipeline

“…𝐿 𝑝 is the length of a pipeline subsection (m), and x is a variable distance along the buried pipeline's length (m). The descriptions and formulas for these parameters are introduced in [9]. Besides, the details of polarization cells'construction and parameters are introduced in [9][10].…”

“…The descriptions and formulas for these parameters are introduced in [9]. Besides, the details of polarization cells'construction and parameters are introduced in [9][10]. Besides, the solid-state polarization cell is represented as a series resistor-capacitor, which blocks direct current while enabling alternating current to flow along the pipeline to the ground without weakening cathodic protection levels.…”

“…Furthermore, the hill-climbing algorithm is used to optimize the parameters of KOH-PCs and SS-PCs to promote the polarization cell's formation for the best performance in relieving the induced voltage without a negative impression on the DC voltage. The investigated pipeline is considered as the continuation of the earlier work[9][10]. Fayoum Gas Company owns the studied pipeline.…”