There is a significant opportunity to better understand and improve the performance of transmission and distribution systems in response to direct and indirect lightning strikes using equipment and data currently available to the industry. To date, the operational analysis of lightning’s impact on power systems (lines) has been limited to information about basic lightning correlations and statistics, which are generally limited to the occurrence of electrical faults within the power system. Now, commercially available protective equipment and data are poised to improve on this limitation. Broadband current transients can now be measured with good fidelity and precise timing within substations and along any long cable on the system using modern digital relays, PMUs, or traveling-wave (TWS) fault locators. Waveforms associated with these transients can be stored and recovered for later use. Additionally, the precise locations of the powerline structures are known and available in geographical information systems. Finally, there is now high-quality lightning “information” from ground-based lightning-locating systems (LLS) with both real-time and historical access. The occurrence of cloud-to-ground (CG) return strokes can be reported with a temporal accuracy of ~250 ns RMS and a spatial accuracy of 100-200m, at least in southern Canada and the United States.
In this work, nine fault cases from two participating utilities were evaluated using lightning information from the U.S. National Lightning Detection Network (NLDN) and broadband fault transient waveforms recorded using Schweitzer 411L relays equipped with TWS recording capability. The fault locations using operational methods were compared with calculations using combined lightning and TWS information. One representative case is discussed in detail, and all nine case findings are summarized. A technical description of the behavior of lightning-caused faults is also included in order to help explain the case study findings.
Lightning, Lightning Protection, Transmission Line Fault, Traveling Wave