Calculation of Characteristic Parameters of Short-Circuit Current of Power Transformer Based on MPM

The short-circuit current waveform is a typical waveform widely used in short-circuit impedance test of power transformer. The three-peak method and the exponential curve method are recommended in IEC 62475 to analyze characteristic parameters of short-circuit current. However, these two methods may result in significant errors when there is more noise. To solve this problem, the matrix pencil method (MPM) is adopted which uses discrete signal to solve the defined state space signal model and calculate dynamically characteristic parameters of short-circuit current, including the initial phase angle, amplitude, and frequency. The results show that the errors of three-peak method, exponential curve method and MPM are 11.40 %, 11.38 % and 0.40 % respectively when the short-circuit current waveform is contained with 20dB Gaussian white noise. MPM effectively suppresses the interference and the calculation accuracy is significantly higher than methods recommended by IEC.