A fault detection and classification technique based on sequential components

This paper presents a fault classification technique for transmission lines based on the sequential fault components for a fast and reliable operation of protective relays. Firstly, symmetrical components of fault current and voltage signals are extracted and secondly, the fault type is classified using the zero and negative sequences. To realize the faulty phases in the grounded faults, a criterion index based on the zero sequence and negative sequence is defined. The imaginary part of the defined criterion index is used. This index is maximum in the faulty phase in a single-phase to ground faults and it is minimum in one of the faulty phases in a phase-phase to ground faults. Also, to identify the 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 with no need of threshold to operate.