الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The close proximity of power lines and buried metallic pipelines has become more and more frequent. Therefore, there has been and still is a growing concern about possible hazards resulting from the influence of power lines on metallic pipelines. Underground pipelines that run parallel to or in close proximity to power lines are subjected to induced voltages caused by the time¬vQlying magnetic fields produced by the power line currents. The induced electro-motive force causes currents circulation in the pipeline and voltages between the pipeline and surrounding earth.
Influences of H. V. lines can result ji-om three types of couplings: capacitive, inductive and conductive. Under fault conditions, the voltages on injluenced pipelines can reach a magnitude between several hundred volts and a few kilovolts. In normal operation, influences are normally much lower, but nevertheless they can make problems. Since the capacitive effect is negligible for the buried pipelines, only the inductive couplings are considered in this research.
The intention of this research is to conduct a comprehensive study on the electromagnetic intelference effects on oil and gas buried pipelines. The objectives of this research are to determine what are the induced voltages and currents at all locations along buried pipelines by using a developed Matlab M-file program which was acquired to assist in the simulation and evaluation of such inductive interference problems, which remain within the vicinity of transmission lines for significant distances, and to check whether these induced voltages are within standards’ safe limit. The research included the present steady-state conditions as well as the fault conditions.
A case study of inductive interference between a pipeline and a transmission line is presented and the interference levels involving, complicated right-of-way, are demonstrated. The study include changing the configuration of tower (vertical or horizontal), the parallel portion between the power line and the pipeline containing the zone of influence, approaching, crossing and the deviating part. Also the study included the voltage of the H. V line (66 and 500kV), effects of conductor height, the coating resistivity, change of the normal load currents, fault currents and its location and the soil resistivity.
The complete interference analysis including both normal and fault conditions were applied on the exiting and actual comprehensive case-study. The results illustrated that the induced voltage on pipeline under both conditions is higher than the acceptable level. Suggested mitigation system based on insulating joints is presented: an alternative mitigation system using grounding method will be designed and examined. A comparison of the effectiveness of the two mitigation methods will be presented. Finally, the performance of earthing system with respect to pipeline length has been investigated. An economical study was carried to assess the effectiveness of the proposed mitigation method.
The conclusive Results may be used as guidelines for designing the mitigation schemes for new pipelines.