Performance evaluation of on-line transformer winding short circuit fault detection based on instantaneous voltage and current measurements

This paper investigates the performance of a recently proposed on-line transformer winding short circuit fault detection approach through detailed nonlinear three-dimensional finite element modelling of windings, magnetic core and transformer tank. The technique considers correlation of instantaneous input and output voltage difference Δ V=(v₁(t)-v₂(t)) and instantaneous input current I=i(t) at the power frequency as a fingerprint of the transformer. The on-line measured ΔV-I locus of healthy and faulty transformer are compared to detect the internal fault. A detailed three-dimensional finite element transformer models based on the physical dimensions, parameters and magnetic core characteristics are developed and used to emulate internal winding short circuit faults and calculate the corresponding transformer ΔV-I locus. Detailed simulations and some laboratory measurements are performed and analysed to investigate the impact of winding short circuit faults on the on-line transformer ΔV-I locus.