Field experience using double-ended traveling-wave fault locating without relay-to-relay comms

The double-ended traveling-wave-based fault locating (DETWFL) method is available in transmission line protective relays and is widely popular, largely due to its field-proven track record, with reported errors being within one tower span (300 m; 1000 ft). The DETWFL method provides accurate fault location results by using current traveling waves (TWs) that arrive at each line terminal after a fault occurs. When relay-to-relay communications are available, the protective relays can collect the necessary time stamps of the initial TW that arrives at each line terminal, automatically calculate the fault location using the DETWFL method, and make the result available to the user within tens of milliseconds. When relay-to-relay communications are not available, an offline DETWFL methodology may be used, in which TW arrival time information is manually collected from time-synchronized relays at both ends of the line after an internal fault occurs and the fault location is computed.

This paper describes the offline DETWFL method and discusses how Red Eléctrica de España (REE), the transmission system operator in Spain, successfully applied it on a pilot project where relay-to-relay communications were unavailable between ultra-high-speed (UHS) line relays installed at both line terminals. The paper includes an analysis of a B-phase-to-ground fault that occurred on a 220 kV, 61.98 km (38.51 mi) line to illustrate the performance of the applied offline DETWFL method. It provides a summary of results from five faults that occurred on this line while relay-to-relay communications were unavailable. These results highlight the improved accuracy of the offline DETWFL method as compared to the single-ended impedance-based and single-ended traveling-wave-based methods.