A correction method for the frequency dependence of eddy current loss power of converter transformer

At present, the eddy current loss of the converter transformer is estimated based on an extrapolation method recommended by the IEC-61378-2 standard and GB/T 18494.2 standard. However, practical measurements already show the recommended method has a poor accuracy for evaluating eddy current loss at high order harmonic frequencies. In this paper, a correction method is proposed for the frequency dependence of eddy current loss considering winding parameters of converter transformer. The eddy current loss power generated by a single a copper conductor of the winding in the magnetic field of a Helmholtz coil changes with the excitation current frequency, and the correction amount of the frequency dependence of eddy current loss power in the converter transformer caused by the skin effect is obtained equivalently. The perforance of the proposed correction is compared with other existing methods, and the numerical results show that the proposed method can fit well to the physical characteristics of eddy current loss power generated by flux leakage of converter transformers in windings, which is helpful to improve the accuracy of estimating the harmonic eddy current loss of converter transformer.