Study On The Frequency Characteristics Of Power Transformer For FRA

As one of the most important electrical equipment, whether can the Power transformers work safely influences the system’s security of the electrical grid directly. So how to know whether the winding of the Power transformers is out of shape or whether the winding shape is under control is very significant.Frequency response analysis(FRA) is a method of system characterization by analyzing its frequency responses. During the past few decades, application of this FRA for power transformers has evolved as a diagnostic tool. Here the main task is to study the frequency characteristics of power transformer for FRA. We discuss the results of the calculations performed in the frequency range 50 Hz–10 MHz and show that the largest variations of both the magnetic field and parameters of the windings.At present time, the method of monitoring winding shape is basic on FRA. After summarizing the experience and method, I improved some parts to make the model better. My progress made with the software named Ansoft-Maxwell is divided into two computation parts, which are small-scale and large-scale. In small-scale part, the power transformers model is computed with considering the skin effect and proximity effect. We contribute the varying of resistance and inductance depending on frequency to the parameters of power transformers changing with frequency. After getting the effective parameters of power transformer winding in small-scale, we can compute the resistance inductance and capacitance easily. Then, on the basic of the resistance inductance and capacitance, we can introduce an R-L-C grid to instead the transformer, which is so equivalent that the frequency response of the grid is just as the power transformer. The frequency response is computed by Matlab.