Modeling and diagnostic transformer condition using Sweep Frequency Response Analysis

Many methods have been developed to justify the condition of power transformer; one of the newest and well known is by using sweep frequency response analysis techniques. The basic concept of this method is by injecting a constant-amplitude of sinusoidal signal under various frequencies (sweep). The current result then compared to the former frequency response (under normal condition) to evaluate the phenomenon that may occur inside the transformer. On this paper, we develop a simulation using a 6/0.22 kV, 100 kVA transformer to simulate 3 kinds of failures, e.g.: fault caused by an inter winding short circuit, axial winding deformation and radial winding deformation. The response curve movement is different depend on the type of disturbance. Short circuits impact for example, gives the movement of curve at low frequency level. To model the transformer, an impedance curve of FRA is being used to find parameters of R (resistive), L (inductive) and C (capacitive). This model is a helpful tool to analyze transformer condition since the parameters have represented the physic of transformer itself.