Abstract: It is conducive to the studies on control technologies of the soured noise in a substation that analyzing the frequency domain properties and the attenuation model of a transformer's noise signal. In this paper, the noises collected from the transformer were analyzed using the full-phase FFT spectrum, and of which the frequency domain curve was obtained. As shown in the spectrogram, the fundamental frequency of the noises was 100 Hz and at this frequency the sound pressure level corresponding to every frequency point reached its maximum. In this study the full-phase FFT spectrum was utilized to obtain the octave band sound pressure levels and to analyze the noise signal of the reference point. Then the acoustic attenuation of the set point could be calculated and the attenuation model could be built by combining the parameters of the substation. The A sound pressure level and 100 Hz sound pressure distribution could be draw. The utilization of the noise attenuation model is beneficial to calculate the substation noise distribution more accurately, what's more, to evaluate their impacts on the surroundings more directly.

Key words: power transformer, active control of noise, all-phase FFT spectrum analysis, attenuation model, noise distribution