Application of Multifractal Spectrum to the Vibration Analyses of Power Transformer under DC Bias

This paper deals with the vibration features of power transformer under DC bias with the method of multifractal spectrum. First, vibration mechanisms of power transformer are analyzed. Then the typical parameters of multifractal spectrum including the width of multifractal spectrum and the absolute value of density difference are calculated to describe the vibration signals of power transformer based on the DC bias experiment of a 10kV power transformer. The experimental results have shown that the width of multifractal spectrum and the absolute value of density difference could fully describe the fluctuation degree and intensity of vibration signals in power transformer. Moreover, the relationship between multifractal spectrum parameters and influence degree of DC bias on power transformer is obtained, which is beneficial for evaluating the ability of the power transformer to endure the DC bias.