Patent ID: 6944554

Claim:
A method for detecting a fault on a transmission line by using harmonics and a state transition diagram, the method comprising the steps of: i) generating an entry confirmation signal and a critical confirmation signal, in which the entry confirmation signal, which is a signal for notifying whether or not a path of apparent impedance enters into a zone, is outputted from a transmission line by utilizing voltage and current of an electric power system and a sum of harmonics components of the transmission line is calculated so as to output the critical confirmation signal, which is a signal for notifying whether or not the sum of harmonics components exceeds a predetermined critical value; ii) applying the entry confirmation signal and the critical confirmation signal to a state transition diagram in order to make a state transition depending on variation of the entry confirmation signal and the critical confirmation signal; and iii) presuming a state of the electric power system by analyzing the state transition in the state transition diagram according to variation of the entry confirmation signal and the critical confirmation signal, thereby determining a fault, no-fault state, and a load-interruption state, in which apparent impedance enters into the zone due to an increase of load.