Spatial acoustic radiation characteristics analysis is the precondition of reducing the noise influence of outdoor power transformer while multi-physical field coupling method can be applied to quantify and reveal these acoustic characteristics of a running power transformer. In this study, based on the theoretical analysis about noise generation and dissemination process, an acoustic radiation model about oil-immersed power transformer was established and verified with field test data in time and frequency domain. Then, far-field analysis and directivity analysis were accomplished to characterize acoustic field of power transformer under multiple operating conditions. Finally, the acoustic radiation influence on potential surrounding buildings were analyzed and discussed. The visual results and conclusion provide acoustic guide for the optimal planning and design about both power substation and ambient buildings.

Noise pollution, air pollution, water pollution and solid waste pollution are recognized as four major environmental pollution sources in the world. Based on the principle of noise reduction, noise reduction materials mainly include sound absorbing material, sound insulation material and noise damping material. In this paper, the mechanism, research progress and development trends of the three kinds noise reduction materials are reviewed and discussed.

Transformer is the core equipment in power plant and substation. Its safety problem directly affects the normal operation of the whole power plant or substation. In the event of fire, it not only affects the normal operation and system load of the system, but also affects the normal operation and load of the system. In this paper, the main causes of transformer fire, fire pre-warning technology and fire extinguishing technology are introduced comprehensively. A on-line detection fire warning technology without blackout is proposed by analyzing transformer operating noise. Finally, the substation fire protection technology from the aspect of civil engineering design is introduced briefly.

Noise characteristic is an important factor need to be considered in the noise control process of power transformers. A transformer noise test platform is constructed in a semi-anechoic room. With this platform, the noise characteristics of an 800kVA/10kV dry-type distribution transformer in different operation voltages and load conditions are tested. Discrepancies of the noise signals in time- and frequency-domains are compared. The A-weight sound pressure levels are also calculated. An interesting result shows that as the increase of load current the noise level decreases gradually. Transformer noise shows some discrepancies in unbalanced load conditions. The noise level of phase-B unbalanced transformer is much lower than that of phase-A and phase-C unbalanced. Harmonic load is found to have obvious impact on transformer noise. The noise level, waveform complexity and the amplitude of odd harmonics of 50Hz increase greatly. The results can be referenced in the noise and vibration control process of power transformers..

In this paper, based on the acoustic impedance tube model established by COMSOL, we studied the influence of the boundary conditions on the frequency characteristics of the damping acoustic plate, the effect of the thickness of the damping layer on the single-layer and double-layer sandwich structure damping acoustic plate. Based on the simulation results, two conclusions can be obtained: (1) the damping layer can effectively increase the sound insulation of the sound insulation plate, and when the thickness of the damping layer is 2∼3 times of the bottom plate thickness, the performance-price ratio is the highest; (2) the sound insulation characteristics of the damping sound insulation plate follow the law of mass, and the sound insulation increases with the increase of frequency under the free boundary condition, while under the fixed support boundary condition, the low frequency sound insulation is larger.

In order to improve the measurement accuracy of corona noise in AC substations, the characteristics of different noise sources are measured and analyzed. Wavelet analysis method is employed to decompose the original noisy corona signal. A stop-band comb filter is designed to process the reconstructed approximate coefficient of the decomposed corona noise. The influence of transformer and reactor noises on that of the corona in the substation is eliminated. The speech enhancement technique based on spectral subtraction method is used to extract the pure corona noise form the filtered signal in which the cooling-device noise in included. The proposed method is applied to process field corona noise in a UHV substation. The 1/3-Octave spectrum and the A-weighted sound pressure level of the purified corona noise are calculated.