Harmonic analysis of inrush current using fast fourier transform

Abstract

This paper presents, analysis of magnetizing inrush current for different voltage angles and harmonic analysis of that inrush current using different FFT windowing techniques. Time domain simulations were used to solve the inrush phenomenon. Square, Welch, Hanning and Parzen windows were used to truncate the obtained inrush current harmonic spectrum for investigation and with parzen windowing the harmonic magnitude is getting reduced due to its reduced side lobes. Inrush current harmonic spectrum obtained by using FFT algorithm in turn discrete fourier transform. Out of different solvers to solve state equation, ode23t solver is used. For an unloaded single phase transformer, inrush current in time domain and harmonic content of inrush current were presented. The results are helpful to estimate harmonics effects in the transformer inrush currents. The results establish a guide line for harmonic elimination due to inrush current and offer an important reference for system design.