Transformer Turn-to-Turn Fault Protection Based on Fault-Related Incremental Currents

Winding turn-to-turn fault (TTF) is one of the most reported reasons for transformer unplanned outage. If its occurrence is not detected at an early stage, it can develop into a costly phase-to-ground fault. In this paper, a novel algorithm based on the fault-related incremental currents is proposed to detect a low-level transformer TTF. This paper shows that the performance of the proposed method is independent of the transformer operating condition. Therefore, it is reliable even under the presence of power system transients such as the external faults. In addition, the proposed algorithm can be configured uniquely and easily. This feature prevents the algorithm from unnecessary trips. These trips can be considered as the general problem that most of the past presented methods face. The experimental tests used for verification of the algorithm show that, regardless of the transformer winding configuration and its pre-fault operating conditions, the proposed algorithm can accurately detect the TTF, which involves only 1% of the winding turns, in less than one cycle of power frequency. The reliable and secure performance of the proposed algorithm shows that it can be widely used in the advanced numerical relays.