Study On Oil Immersed Transformer Noise Suppressing Methods Based On Basic Silencing Unit

Together with accelerating urbanization and ongoing power grid upgrading in China,the integration degree between power infrastructure such as substations and urban function blocks is gradually increasing,and corresponding spatial distance is decreasing at the same time,resulting in the oil immersed transformer noise problems,which were not noticeable before,are gradually receiving more attention.Therefore the research on the noise suppression method of transformer inside substations owns positive effect on both improving the sound environment quality around the substation and promoting the service grade of power grid operators.Aiming at transformer audible noise absorbing and surrounding sound environment quality upgrading,in this paper,transformer spatial acoustic radiation characteristics analysis,basic silencing unit establishing and analysis and transformer audible noise suppression inside substation were accomplished following the progressive logic.Firstly,the establishment of multi-field coupling models about oil immersed transformer acoustic radiation inside different types of substations was completed,the spatial acoustic radiation characteristics analysis of both split type transformer and integrated transformer were then accomplished according to FEM and Fusion FEM-BEM respectively and corresponding three-dimensional distribution characteristics in the frequency domain of each transformer external acoustic field were obtained.These distribution characteristics provide guidelines for both establishment and location selection of the silencing unit inside substation.Secondly,according to the obtained transformer spatial acoustic radiation characteristic and operating environment inside substation,the combined method of porous sound absorption,vibration sound absorption and sound insulation was established as the noise suppression idea.Sound absorbing and insulating material screening and corresponding material specifications confirming were then completed.After that,considering universal design principles,the establishment of basic silencing unit structure,which is suitable for noise suppression inside substation,was accomplished.Through the sound absorbing and insulating test,it can be seen that this basic silencing unit not only owns good sound absorption effect,but also owns the potential self-adjustment ability accompanied by the changing of sound source characteristics.Then,on the basis of replacing the original sound absorbing structure with the fixed frequency silencing unit,according to the improved indoor substation low-noise design method based on the concept of soundscape compatibility,the potential noise suppressing measures were expanded into electrical design sector,the layout adjustment of indoor substation cabins and the position optimization of fixed frequency silencing unit were then accomplished.Through comparative analysis,it can be seen that the increased diversity of noise control measures contributes to a more efficient substation soundscape planning and management at lower costs,after the cabins layout adjusting,replacing with fixed frequency silencing unit and corresponding position optimizing,the community acceptance about the indoor substation noise level can be easily achieved.Finally,combined with the spatial acoustic radiation characteristics of the transformer inside the semi-household substation and the universal design principles,the core parameter calculating,optimizing method establishing,prototype testing and analyzing and noise suppression effect evaluating of servo silencing unit were accomplished in order.The test and calculation results show that the servo silencing wall composed of the servo silencing units can not only shrink the noise coverage on the surfaces of surrounding noise sensitive building and damp the noise peak,but also owns the ability of selecting and absorbing the protruding frequency band of the transformer noise.Therefore,the usage of servo silencing unit is more conducive to the soundscape compatibility after the semi-indoor low-noise improvement.