电力变压器噪声除了本体噪声产生的低频分量,还包含冷却风扇产生的中高频噪声。有源降噪方法对低频噪声控制性能好,且灵活可控,但降噪效果受制于通道数量。在不增加通道数量的前提下,为了拓宽降噪频率范围,提出声子晶体材料与有源控制相结合的降噪方法。以DSP为核心控制器搭建了基于LMS算法的双通道有源降噪系统,在此基础上开展了嵌入声子晶体材料的有源降噪系统降噪性能验证实验研究。实验结果表明,针对变压器100~400 Hz的低频噪声,双通道有源降噪系统单频最大降噪量约20 dB,多频总降噪量可达9 dB。设计了对500~1 000 Hz中高频噪声抑制作用明显的声子晶体材料,对600 Hz单频降噪量约14 dB。嵌入声子晶体材料的双通道有源降噪系统,最大总降噪量可达16 dB,优于单纯的有源降噪。可见,声子晶体材料与有源控制相结合,拓宽降噪频率范围、提高降噪性能的方法是可行性的。
Power transformer noise includes not only the low-frequency components generated by transformer vibration,but also the medium and high frequency noise generated by the fan. Active noise reduction method has good performance in low frequency noise control,but the effect of noise reduction is limited by the number of secondary channels. In order to widen the frequency range of noise reduction without increasing the number of channels,a method combining phononic crystal materials with active control was proposed. A dual-channel active noise reduction system based on LMS algorithm is built with DSP controller. The verification experiment on the performance of the active noise reduction system combined with phononic crystal material was carried out. The results show that the maximum single-frequency noise reduction and the total multi-frequency noise reduction are about 20 d B and 9 dB respectively for 100 ~ 400 Hz low-frequency transformer noise. A phononic crystal material with distinct suppression effect on noise between 500 Hz and 1 000 Hz was designed. The single-frequency noise reduction of the material at 600 Hz is about 14 dB. The maximum total noise reduction of the two-channel active noise reduction system combined with phononic crystal material can reach 16 dB,which is superior to the active noise reduction without phononic crystal material. Therefore,it is feasible to combine phononic crystal materials with active control system to widen the noise reduction frequency range and improve the noise reduction performance.
Science Technology and Engineering
active noise control
photonic crystal material