Research on Active Noise Control Method Compensating for Acoustic Metamaterial Noise Barrier in Transformer Noise Reduction

Noise barrier with acoustic metamaterial has application prospect in power transformer noise reduction due to its low frequency noise reduction advantages. The acoustic diffraction along the edges of the noise barrier decreases the overall noise reduction obviously. An active noise control (ANC) method combined with noise barrier is proposed to counteract the diffracting sound waves near the edges of the noise barrier. The noise barrier is composed of the Hilbert fractal acoustic metamaterial (HFAMM) units with good sound insulation characteristics at low frequencies. The transmission loss (TL) of the HFAMM unit is higher than 20dB at the main frequencies of the transformer noise theoretically. The experiment system including the acoustic metamaterial noise barrier and the ANC system is established. The sound pressure level with ANC on the specified points in the target area is more than 10dB lower than that without ANC in the experiment. The results prove that the new method is effective for improving noise reduction performance of the noise barriers.