Novel Technique for Location Identification and Estimation of Extent of Turn-to-Turn Fault in Transformer Winding

This article presents a novel technique for diagnosing a turn-to-turn fault at the incipient level inside the power transformer winding using frequency response analysis (FRA). Utilizing lower frequency region of FRA in case of prefault and postfault conditions of transformer windings, the proposed technique determines the deviation in equivalent inductances. Based on the deviation, a location factor is derived, which indicates location of fault, by calculating accuracy factor (x) corresponding to each section of the winding. Thereafter, the extent of turn-to-turn fault and number of faulted turns are determined based on the accuracy factor of the faulted disk. The performance of the proposed technique has been validated through a simulation model as well as from two different laboratory-developed winding models and 400 kVA real filed transformer. The results designate that the developed technique is proficient to estimate location of turn-to-turn fault even when number of faulted turns are lower than 5% of the total turns. Its response remains immune against winding configurations and lead error encountered during measurement. Eventually, a comparative assessment of the proposed approach with various other approaches indicates its eminence in terms of turn-to-turn fault localization and estimation of fault extent and faulted turns.