Metallic Gas Pipelines Research Articles

Influences of faulty AC underground power cables on the neighbouring metallic gas pipelines

In this paper the impacts of faulty underground power cables on their neighboring metallic buried pipelines have been investigated, specifically in the event of line to ground faults of these cables, as well as the use of barrier mediums to reduce this effect. In this paper, the conduction current generated in metal pipeline as a result of faults in underground cables is studied.To reduce the induction voltages affecting the metallic pipelines, it is proposed to use a barrier between the cable and the metallic gas pipes. The effects of the type of barrier material, its thickness, and its distance from the cable on both the induction voltages and currents generated in the metal pipes are investigated. It is found that the use of XLPE barrier with thickness of 5 mm at 600 mm space from the pipeline reduces the induced voltage to be 40.02 % - 40.6 % of its value when concrete barrier is employed and 98.6 % - 98.5 % with the use of copper barrier respectively. Similar results proved that the increase of the barrier thickness is effective in reducing the induction voltage. The metal barrier has proven to be the best in reducing the effect of the induction voltage resulting from the line to ground faulty underground power cable on the neighboring metal pipes.

Overhead transmission lines impacts on neighboring buried metallic gas pipelines

Buried metallic pipelines are used to transmit the services such as natural gas and petroleum products to the citizens. Sometimes these pipelines are constructed in the same pathway of the overhead transmission lines to save the additional right-of-way cost, and to avoid the destruction of agricultural lands. AC voltage is induced on these pipelines by the power line electric and magnetic fields. There are many mechanisms that describe the AC voltage inducing on these pipelines; capacitive coupling describes the pipelines induced voltage by the power lines electric field, inductive coupling characterizes the induced voltage caused by the OHTLs electromagnetic fields and conductive coupling is created in buried pipelines near to OHTLs by earth fault current. In the present paper, the induced voltages of pipelines created by overhead transmission lines due to the different couplings are investigated in normal condition of operation as well as line to ground fault. The current of the coating discharging and AC corrosion is investigated. The induced overvoltage appearing on the natural gas pipeline is measured in steady-state condition of the transmission circuits operation. Proposed mitigation technique for induced voltage based on earthing polarization cells is presented and investigated. Moreover, the paper studied the influence of applying different configurations of the proposed technique on the AC induced voltage.

Screening of the high voltage overhead transmission lines impacts on the neighboring metallic gas pipelines based on the distributed KOH-PCs

Buried metallic pipelines are used to transmit the natural gas and petroleum products to the citizens. Sometimes these pipelines are constructed in the same pathway of the overhead transmission lines (OHTLs) to save the additional right-of-way cost, and to avoid the destruction of agricultural lands. AC voltage is induced on these pipelines by the power lines electric and magnetic fields. There are many mechanisms that describe the AC voltage inducing on these pipelines; capacitive coupling describes the pipelines induced voltage by the power lines electric field, inductive coupling characterizes the induced voltage caused by the OHTLs electromagnetic fields and conductive coupling is created in buried pipelines near to OHTLs by earth fault current. In the present paper the induced voltages of pipelines created by OHTLs due to the different couplings are investigated in normal condition of operation as well as line to ground fault. The current of the coating discharging and AC corrosion are investigated. The induced overvoltage appears on the natural gas pipeline is measured in steady state condition of the transmission circuits operation. Moreover, this paper represents the mitigation of the induced voltages by using two different KOH-PCs systems.

Real Time Implementation of Incremental Fuzzy Logic Controller for Gas Pipeline Corrosion Control

A robust virtual instrumentation based fuzzy incremental corrosion controller is presented to protect metallic gas pipelines. Controller output depends on error and change in error of the controlled variable. For corrosion control purpose pipe to soil potential is considered as process variable. The proposed fuzzy incremental controller is designed using a very simple control rule base and the most natural and unbiased membership functions. The proposed scheme is tested for a wide range of pipe to soil potential control. Performance comparison between the conventional proportional integral type and proposed fuzzy incremental controller is made in terms of several performance criteria such as peak overshoot, settling time, and rise time. Result shows that the proposed controller outperforms its conventional counterpart in each case. Designed controller can be taken in automode without waiting for initial polarization to stabilize. Initial startup curve of proportional integral controller and fuzzy incremental controller is reported. This controller can be used to protect any metallic structures such as pipelines, tanks, concrete structures, ship, and offshore structures.

Effect of electromagnetic field of overhead transmission lines on the metallic gas pipe-lines

This paper presents a study of the overhead transmission lines (OHTLs) electromagnetic fields effects on the metallic gas pipelines. The inductive and conductive voltages between the overhead transmission line and metallic gas pipelines, in normal operation and under phase to ground fault condition of the overhead transmission lines, are calculated. ATP software is used to simulate the OHTL under faulty condition. MATLAB program is used to calculate the induced voltages taking into account the effects of various parameters, such as: separation distance between the OHTL and the metallic gas pipelines, case of transmission line (phase to ground fault condition or normal operating condition), the screening factor and the soil resistivity on the magnitude of the induced voltage along the length of the metallic gas pipeline. The method used to calculate the induced voltage by inductive is based on the well known method “distributed source analysis”. Case study, to measure the induced voltage on the metallic gas pipelines from OHTL under normal operating condition, is presented. The comparison between the measured and calculated results shows a good agreement between them.

Original Approaches for Solving Electromagnetic Interference Problems

The accurate calculation of the current densities induced in layered soil by HV transmission lines in normal conditions is one of the most important steps in the study of the electromagnetic interference between transmission lines and underground metallic structures (i.e. metallic gas pipelines). In electromagnetic interference problems, the best way to investigate the soil's behavior as conducting media is to determine the current distribution within ground. The aim of the present paper is to examine the level of influence that soil layers with different resistivity have on the induced current densities. New analytical formulas for the induced current densities in the two-layer soil case are derived. The determined formulas contain semi-infinite integral terms which are calculated through a stable and efficient numerical integration scheme, in order to overcome the problems arising from the oscillate form of the infinite integrals. In the second part of the paper, the author's contribution relates to the exposure and implementation of a robust Monte Carlo simulation method, in an original approach, for solving ill-posed synthesis magnetic or electric field problems.