Analysis of unexplained flashovers on a 69 kV transmission line using measured lightning data

The availability of cloud-to-ground lightning strike information has led to the development of methodologies that use these data to determine causal factors of power system interruptions. The information provided by networks of remote lightning sensors includes the geographic location, time, estimated peak current (kA), and various quality parameters that explain the statistical integrity of the data. Lightning strike data, coupled with a geographic information systems-based analysis, are an effective way to understand the relationship of power system interruptions, relative to lightning data characteristics. This paper presents a case study that demonstrates the effectiveness of this methodology for an electric utility in the United States. Lightning strike data were correlated to the occurrence of two transmission line interruptions and led to conclusions about the cause. Furthermore, estimated peak current information about the suspect strokes led engineers at the electric utility to conclude the cause to be shielding failure, due to unique terrain characteristics which physically expose the line making it susceptible to additional failures