考虑铁芯接缝的电力变压器空载噪声计算*

硅钢片磁致伸缩导致的铁芯振动是电力变压器空载噪声的主要原因,铁芯的接缝结构对空载噪声的影响很大。为研究不同接缝结构对铁芯噪声的影响,本文提出了一种基于接缝区材料磁致伸缩特性等效的方法,首先对含有接缝气隙的铁芯模型进行磁场分析,对接缝区的材料分别进行磁化特性等效及磁致伸缩特性等效；其次采用等效的材料,基于有限元法对一台110kV电力变压器进行磁-力-声耦合分析,计算不同模型的噪声。最后通过对含有不同接缝结构的变压器开展噪声测试,验证了计算方法的有效性。结果表明考虑接缝结构的模型与实测数据有更小的误差,采用接缝结构等效的建模及计算方法可以实现接缝结构对噪声影响的计算。

Simulation of no-load noise of power transformer considering core joints

The core vibration caused by magnetostriction of silicon steel sheet is the main cause of no-load noise of power transformer, and the joint structure of core has a great influence on the no-load noise. In order to study the effect of different joint types on the core noise, a method based on the equivalent magnetostriction characteristics of the joints is proposed in this paper. Firstly, the magnetic field of the core model with joints is analyzed, and the magnetization and magnetostriction characteristics of the materials in the joint area are equivalent respectively. Then, core joints of a 110kV power transformer are defined by new material with equivalent properties and the magnetic-force-acoustic coupling analysis is carried out to simulate the no-load noise based on the finite element method. Finally, the effectiveness of the calculation method is verified by the noise test of the transformer with different joint types. Result shows that there is less error between the simulation considering the joints and the measured data. The equivalent modeling and calculation method of the joint structure can be used to calculate the effect of the joint types on the no-load noise.