New High Efficiency Sound Insulation Structure For Typical Distribution Transformer Body Noise Reduction

The continuous expansion of socialized production has led to the steady rise of electricity consumption in the whole society.The site selection of some substations has become closer and closer to the population distribution areas,and the noise of distribution transformers caused by it has become one of the main factors disturbing the quality of life of residents near the substations.In order to solve the noise and vibration problems of distribution transformers,combining the sound insulation mechanism of constrained damping compound structure and the sound and vibration characteristics of distribution transformers,a new type of efficient sound insulation structure suitable for the typical distribution transformer body noise reduction is researched and developed.This paper has carried out the following research contents:Firstly,based on the actual measurement,the coupling relationship between the vibration characteristics of 35 k V and 110 k V typical distribution transformers on the tank wall and the characteristics of near-field noise and far-field noise radiation are analyzed and discussed,and the attenuation characteristics of noise radiation along the direction of the tank wall of distribution transformer are studied.The results show that the vibration and noise radiation energy of distribution transformer tank wall are mainly concentrated in the frequency range of 200 Hz to 500 Hz,and there is a strong coupling between the wall vibration of distribution transformer and the near-field noise radiation and the far-field noise radiation.Secondly,combined with the acoustic and vibration characteristics of the transformer,operating environment and working conditions as the design basis,the selection of the new efficient sound insulation structures for distribution transformers is carried out.The Constrained Layer Damping Structure was used as the structure configuration,and two combination strategies were proposed: different combination methods under the same thickness and different combination methods based on the mass law.The design optimization of the structure was carried out,and the combination form of the Constrained Damping composite Structure was finally determined.The finite element model was established by the commercial finite element software COMSOL Mutiphysics,and the numerical simulation analysis of the normal incident acoustic transmission loss was carried out.The results were verified by the standing-wave tube measurement experiment with the four-sensor method.The results show that the new sound insulation structure selected has the characteristics of light and thin,high sound insulation and low cost.Then,the numerical simulation analysis of the 10 k V true transformer before and after adding the new high efficiency sound insulation structure is carried out.The noise and vibration characteristics of the internal structure of the transformer are simplified.The geometric center of the oil tank is set as the point sound source for excitation.The sound radiation distribution and equivalent stress distribution of the laboratory platform and factory platform of the 10 k V true transformer before and after the addition of the new efficient sound insulation structure are analyzed.The results show that the noise reduction in the range of 50-1000 Hz is between 4 d B to 7d B,and the equivalent stress amplitude of the transformer shell structure is significantly reduced after the addition of the new high efficiency sound insulation structure.The new high efficient sound insulation structure can eliminate the high sound pressure level at some frequency points caused by resonance by changing the natural frequency of transformer.Finally,the experimental study on the true transformer of 10 k V before and after adding the new high efficiency sound insulation structure is carried out.With the white noise emitted by the12-hedral all-directional ball sound source as the excitation condition,the noise emission distribution characteristics of the laboratory platform of 10 k V true-type transformer were analyzed.Distribution characteristics of ambient background noise and noise radiation are studied in a 10 k V true-type transformer plant platform under no-load condition.Results show that the added new high efficiency before and after sound insulation structures,laboratory platform of each measuring point between 2d B to 4d B insertion loss,factory platform in 40/50/100/250/315/1000/1250/1600/8000 Hz for the center frequency of 1/3 octave band,insertion loss between 3 d B to 12 d B,the spectrum covers the transformer noise of main energy distribution scope of ontology.In conclusion,the new high efficiency sound insulation structure has obvious suppression effect on the transformer body noise.