Because of the flashover fault caused by lightning stroke

the amplitude of the initial traveling wave of current traveling wave is large

and it is accompanied by a large number of oscillations. However

the amplitude of reflected traveling wave(the reflected wave of fault point and the reflected wave at the end bus)is much smaller than the amplitude of the initial traveling wave. Therefore

it is difficult to identify the reflected waves at fault points on the same observation scale. At the same time

there are no fully equal double circuit lines in the field. Based on this

the distribution characteristics of traveling waves observed on the time axis of the two coordinate axes of the unequal-length double-circuit on the fault line and the measurement end of perfect return line are analyzed. The method of joint observation and identification of fault traveling wave on two scales of fault line measurement end and non-fault line measuring end is proposed. The fault initial wave to the time which comes from fault line and sound line measurement end is used to realize the fault location of the unequal-length double circuit. A large number of measured data show that joint observation on two scales of fault line measurement terminal and non-fault line terminal

especially lightning stroke flashover fault

can identify the fault traveling wave reliably and correctly

and achieve reliable and precise ranging of unequal-length double circuit lines.