Directional power components based on fundamental frequency components and sequence components can identify the positive-direction faults and anti-faults of traditional transmission lines by taking advantages of line backside impedance. However

due to the long refraction and reflection time of wave processes in half-wavelength lines

the directional components cannot determine quickly and accurately the anti-faults after protection startup. Thus

a new fault-component based directional protection method for half-wavelength lines is proposed. In this method

the special amplitude phase relationship of phase-to-phase deviation between super-imposed fundamental frequency components of voltage and current is utilized at the initial stage of the anti-fault

and then the waveform identification coefficient at each end of lines is calculated respectively. At the same time

the super-imposed fundamental frequency components and negative-sequence components are used as the auxiliary criterion to judge the positive-direction faults

which constitute the fast directional protection scheme of the semi-wavelength transmission lines together with the proposed new method. In this scheme

the fast action logic based on the waveform identification coefficient and the fast recognition of the anti-fault is adopted to realize the fast action of the zone faults. Finally

the simulation results by PSCAD/EMTDC show that the method can accurately identify the positive-direction faults and anti-faults to achieve the fast tripping of half-wavelength lines.