Inrush Current Analysis Based on FFT and Wavelet

From the view of engineering,most countries in the world use differential protection as main protection of transformer.On the one hand,transformer differential protection needs to face the common TA protection of the main equipment also have to face on the other hand,the transformer inrush current problem.In order to ensure the selective and sensitive,it is necessary to avoid the failure of the transformer of the largest external imbalances in current,at the same time switch on the correct identification of no-load inrush current and internal short circuit fault current.In this paper,mechanism and characteristics of the transformer inrush current are researched based on FFT and wavelet analysis.The transformer model which is closed in the state of no-load is simulated using of MATLAB software SIMULINK/PSB toolbox.Inrush current is decomposed with POWERGUI/FFT analysis and wavelet analysis GUI toolbox,and gains the useful information to solve the problem of transformer inrush current.