A Fault Detection and Classification Technique Based on Sequential Components

This paper presents a fault classification technique for transmission lines based on the fault sequence components, for fast and reliable operation of protective relays. First, symmetrical components of fault current and voltage signals are extracted. Next, the fault type is classified using the zero and negative sequences. To realize the faulted phases in ground faults, a criterion index based on the zero and negative sequences is defined. The imaginary part of the defined criterion index is used. This index is maximum in the faulted phase in single-phase-to-ground faults, and it is minimum in one of the faulted phases in phase-to-phase-to-ground faults. In addition, to identify ungrounded faults, a different criterion index using the positive and negative sequences is defined. The results show that the scheme provides a fast fault classification, without the need for a threshold to operate.