In the joint-use corridors where both pipelines and ac electric transmission lines are present, a portion of the energy contained in the electromagnetic field surrounding the electric transmission lines is captured by each pipeline, resulting in induced ac voltages which vary in magnitude throughout the length of each pipeline. During a fault on any of the transmission lines, energization on the earth by supporting structures near the fault can result in large voltages appearing locally between the earth and the steel wall of any nearby pipeline. Some form of mitigation is usually required to reduce these voltages to acceptable levels for the protection of personal and the pipeline itself. This paper presents a new mitigation design approach which not only reduced ac voltages effectively and economically, but also provide cathodic protection for the protected pipeline. Performance of this new mitigation method is illustrated with results from computer simulations, which show how important it is to have an accurate electric model of the soil structure in any interference study. The method which combines the effectiveness of grounding conductors and gradient control wires, mitigates both inductive and conductive interference and provides cathodic protection. Two other methods are discussed: lumped grounding which is considerable less effective than the gradient control wire method, and cancellation wires, which are more expensive and may simply export pipeline potentials to unexpected right-of-way locations and thus constitute a safety hazard.
Recent advances in the mitigation of ac voltages occurring in pipelines located close to electric transmission lines
Letzte Entwicklungen bei der Verminderung von induzierten Wechselspannungen in Rohrleitungen in der Nähe von Hochspannungsfreileitungen
IEEE Transactions on Power Delivery ; 9 , 2 ; 1090-1097
1994
8 Seiten, 9 Bilder, 2 Tabellen, 19 Quellen
Aufsatz (Zeitschrift)
Englisch
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