الفهرس | Only 14 pages are availabe for public view |
Abstract Electromagnetic fields produced by high voltage overhead transmission lines are still considered an important subject in several research areas due to their harmful effects on human health and environment. These Electromagnetic fields produces high level of induced voltages at nearly steel pipelines. This problem appeared obviously at the Natural Gas Transmission Network at the last 10 years where the pipelines share the same routes with high voltage transmission lines. The induced voltages at Gerga / Aswan pipeline and Taba / sharm pipeline reached to very dangerous levels and some technicians have been strongly shocked and exposed to death. Environmental Impact Assessment studies (EIA) are very important to be carried out before establishing of power line projects to evaluate the electromagnetic effects on the project environment especially on nearby pipelines as well as its social and health impacts. This thesis presents a comprehensive study to the induced voltages along a section of Taba / sharm Gas pipeline, 500 mm2 cross section area and 208 km length which lies in the same right of way with an actual sophisticated overhead transmission line tower carrying four circuits (two 220 kV circuits and two 66 kV circuits) under different loading conditions. Three different mitigation methods were applied along the pipeline under normal and abnormal conditions (balanced, severe unbalanced loading and during different short circuit conditions). Mitigation techniques using cancellation wire, gradient control wires and using polarization cells were investigated. Results obtained showed that polarization cells give more efficient values for reduction of induced voltages using the suggested technique. A model was developed using the Alternative Transients Program (ATP) to simulate the whole system with the different mitigation methods. The effect of transmission lines maintenance scenarios on the induced voltage levels on the gas pipeline was also investigated. An economic impact assessment technique was developed to determine the appropriate and economic method. |