Discrimination between internal current and external fault in three phase power transformer by Using alienation coefficient

Transformers are essential equipment in a power system and require reliable solutions for their protection to ensure smooth operation. This paper proposes a new method based on an alienation coefficient analysis of waveforms to discriminate between external and internal faults that may take place in a three-phase transformer. This method depends on variations in the waveforms of currents which occur due to faults. it depends on the three phase current measurements which can be calculated on the transformer, and thus, does not need extra devices. This method can be used for fault detection and classifying faulty phases. For usage in advanced protection plans, the alienation strategy is appropriate in this field. The new technique was practically applied in the laboratory, and the results were obtained using the MATLAB and LabVIEW software. The proposed technique is quick to such an extent that it can provide conclusions in less than 3ms.