Turn to turn faults effect on inverted windings FRA of Power Transformer

In this paper, a model for transformer is propounded that can calculate frequency response of winding in high frequency. One of the most suitable methods for testing the normality of transformer is studying winding frequency response through which loop-to-loop connection diagnosis will be possible. The principle of this method is that variations in the geometric or electric structure of transformer will affect its FRA, and its difference from a normal transformer FRA or windings of other phases, shows the fault of transformer winding. By this model finding relation between FRA of healthy and faulty winding is achievable. In order to get more accuracy, parameters of equivalent circuit were estimated by FEM based on design geometrical information. Considering frequency dependency of elements has culminated to more accurate results. Analyzing equivalent circuit is implemented in MATLAB and our focus is on FRA of high voltage winding in the case of turn to turn fault. The FRA of healthy and faulty is determined and compared. Fault Resistance effects on the windings FRA and it is necessary to find out the effects, so the model analyzed with variable resistance. At last the results of the variable resistance are plotted.