Frequency Response Curves of Windings with Bulge Deformation in Power Transformers

Transformer is one of the most important components in power system. However, great economic losses and industrial accidents can result from its faults, and one of the most serious of all faults is transformer winding deformation. And frequency response analysis (FRA) is gaining popularity in detecting power transformer winding deformation for its accuracy. And multi-conductor transmission line model is one of the commonly used models of FRA. To determine the relationship between frequency response curve and the degree of winding bulge deformation, we performed the simulation and analysis on two kinds of windings using multi-conductor transmission line model. And the fitting curve of resonance point frequency offset shows that the frequency response curve will move to the left when there is bulge deformation, and the more severe the fault is, the more it moves to the left. In addition, the distance between resonance points is closer in the low-frequency range. However, as the frequency increases, the frequency difference becomes larger and larger.