电力变压器缩尺模型振动试验及其声学模型

首先,根据某电力变压器的缩尺比例模型在不同激振频率下箱壁振动相位和振幅的测试结果,得出当激振频率超过7阶模态频率时,其相位和振幅呈随机分布的结论,确定了电力变压器简化为点声源的划分形式;其次,建立了户外半开空间内电力变压器相干虚源模型,该模型考虑了声线多次反射形成的无限个虚源之间的干涉效应;最后,应用该相干虚源模型对存在相位关系的电力变压器组辐射声场进行计算,通过与边界元模型、ISO9613模型计算结果与实测值进行对比。结果表明,该相干虚源预测模型因考虑了相位信息,能反映出声波在不同位置处的传播趋势,比原有的ISO9613模型更为准确,验证了所提理论模型的可行性。

The Vibration Test of Power Transformer Scale Model and Its Acoustic Model

A power transformer is one of the main sources of noise in the power transmission and transformation system, and the accuracy of outdoor noise prediction directly affects noise evaluation and control. Based on the test results of the wall vibration phase and amplitude in different excitation frequencies, this paper concluded that the distribution of the model phase and amplitude were random when the excitation frequency reached up to the seventh modal frequency. Thus, the zoned format could be simplified from power transformer to point sound source. Further, the coherent image source model of the power transformer was established considering the interference effect among the infinite image sources caused by the multiple reflections of sound rays. Finally, the sound field of the power transformer groups was calculated using the proposed model, and the solution was compared with that using the ISO9613 and BEM model. The results show that the coherent source model can predict the trend of the spread of sound waves at different locations considering the phase information, and the calculated value was closer to the exact value than that of the ISO9613 model. The above research results validate the proposed theoretical model.