Correlating voltage sags with line faults and lightning

In order to position themselves for the coming competitive energy marketplace, utilities must judiciously improve their transmission and distribution system to provide the highest quality power to their customers. In this light, the knowledge of what caused particular voltage sags can be invaluable in deciding where to spend a limited capital improvement budget. This article describes an integrated system of databases that correlates voltage sags with transmission line faults and any corresponding lightning strikes that caused the fault. By determining the critical locations for susceptibility to lightning-induced faults, remedial measures can be tactically implemented to improve both the lightning protection and the fault performance of the system. In addition, disturbances not caused by lightning can be identified so that other causes can be determined.