The invention relates to a triangular looped network
ranging distance
continuation method and belongs to the technical field of power
system relay protection. The method includes the steps that according to a triangular looped network composed of
power transmission lines among three
transformer substations, a travelling wave
ranging device is arranged only in the
transformer substation connected with a
busbar M, and the lines l1 and l3 which are adjacent to each other are monitored. After a fault happens in the
power transmission line l2, which is not monitored by the travelling wave
ranging device, in the looped network, initial fault travelling
waves reach busbars N and P at the two ends of the fault line and are transmitted to the perfect lines in the looped network through the busbars, current travelling
waves of a measuring end TA1 of the perfect line l1 are acquired through the travelling wave ranging device, the time for the initial fault travelling
waves to reach the TA1 through the perfect line l1 and the time for the initial fault travelling waves to reach the TA1 through the perfect line l3 are respectively recorded, then, the
time difference delta t is calculated, and finally, the fault distance x is calculated according to the overall length of all the lines of the triangular looped network and experimental
wave speed. Theoretical analysis and a
simulation result show that the method is not affected by fault instantaneity, fault transition resistance changes and other factors, and a ranging result is accurate and reliable.