Realization scheme of directional unit protection based on travelling wave integral

A set of scheme of directional unit protection based on travelling wave integral is designed. For main components in this scheme, such as fault phase selection component, fault direction discrimination component, lightning stroke and circuit breaker operation verification, etc., the theoretical analysis and criterion construction and simulation test are all carried out. Simulation data demonstrate that the fault conditions hardly have any influence on the performance of proposed discrimination principle for fault direction; the identification criterion for different signals can correctly distinguish fault signals from various disturbance signals and fault phase selection criterion can precisely choose fault phase. This protection technique has clear principle and simple construction, which is promising to be used in practical power engineering.