New approaches to calculation of lightning induced voltages on overhead lines for power quality improvement

Lightning events that take place between cloud and ground, the so called “cloud-to-ground” discharges, can cause damage when they strike directly or strike nearby to a structure. For low and medium voltage power distribution networks, indirect lightning events are more frequent than direct strikes, and may cause power outages, disturbances, or failure of electronic and electrical equipment, due to the over-voltages produced. In order to reduce the effects of lightning flashes, it is necessary to provide suitable protection measures. An accurate evaluation of lightning induced voltages is therefore essential. Recent progress in the area of lightning induced voltages is significant, both from numerical and analytical points of view. Most of the analytical results proposed so far in literature are approximated and/or incomplete, as will be shown in the thesis. The aim of the work is to present new analytical approaches to the evaluation of lightning induced voltages on overhead power lines, that allow to overcome errors and/or approximations present in the solutions available in the literature. Predictions of the proposed solutions will be also compared to those based on the other approaches found in the literature in order to check their validity and accuracy.