Performance Assessment of a Wavelet-Based Differential Protection scheme in the Inter-Turn Fault Detection in a Transformer

Faults inside of the power transformer protection zone are commonly detected by the traditional phase and negative sequence differential elements. However, the detection of turn-to-turn and turn-to-earth faults is still a challenge for the traditional phase differential element, especially when the transformer operates with maximum load. Furthermore, the conventional algorithm usually is only able to detect turn-to-turn and turn-to-earth faults at a severe stage, when it involves a larger percentage of winding turns or phase-to-earth fault condition. This paper presents a comparison between the performances of existing conventional and wavelet-based differential protections regarding the detection of turn-to-turn and turn-to-earth faults in a power transformer under different loading scenarios. The wavelet units were more sensitive, faster, and less affected by the load variations, being a promising alternative for detecting transformer failures and preventing the fault evolution to more severe stages.