Analysis of Frequency Response of Power Transformers Considering Frequency Variation Characteristics

The paper takes a 110kV power transformer as the research object and obtains the permeability characteristics of the iron core under frequency variation through numerical calculation. Then, frequency-related parameters of transformer winding inductance were calculated by establishing a finite element model. A winding trapezoidal equivalent circuit model considering frequency variation characteristics is established using transformer winding double cakes as units, and the frequency response of the winding considering frequency variation characteristics is obtained through analysis and modeling. The results indicate that due to the influence of the eddy current effect, the transformer core undergoes a demagnetization effect. The anisotropy of the stacked iron core of the transformer gradually decreases with increasing frequency, and the winding inductance also decreases with increasing frequency. Under the action of broadband sine excitation signal in frequency response measurement, the winding inductance value decreases by 27.7%. Considering the influence of eddy current losses in transformer cores and the frequency variation characteristics of model parameters can improve the modeling accuracy of equivalent circuit models for windings to a certain extent.