Comparison of simulated and recorded transients for travelling wave fault location

In order to assist in the location of EHV transmission line faults using travelling wave transients a program has been devised where the transients are simulated and compared with those recorded. The simulation scheme is based on the well-known ATP program, which has been found to be satisfactory for sample step times of 800 ns. The fault transients have been recorded at a 800 ns sample rate via a current probe attached to the secondary circuit of the current transformers. An offline analysis program has been written in Matlab™ which then converts the simulated transients into a form that allows direct comparison with the recorded transients and also provides extra analysis routines. This greatly improves the confidence in a given fault location estimate. Example faults recorded on the ScottishPower EHV transmission system are given which demonstrate the utility of this scheme.