Digital travelling wave protection method for power transmission line and its relay and protection system

A digital travelling wave protecting method for electric power transmission lines and its relay and protection system is disclosed. The said system is composed of digital travelling wave relays containing hardware and firmed software and high-frequency carrier communication unit consisting of high-frequency transceiver and high-frequency carrier channel-power transmission lines. The said method features that the action results of said relays at both ends of a power transmission-line are compared with each other to judge if there is a failure on the line. Its advantages include fast response (5 ms for relay action and 15 ms for protection action).