Simulation Study of Transformer Core Vibration Characteristics Under Harmonic Current

In order to study the effect of harmonic current factor on the vibration characteristics of oil-immersed transformer core, this paper establishes a three-dimensional transient simulation model based on Comsol Multiphysics finite element software to carry out multi-field coupling simulation. Under the condition of constant rated current RMS value, the effects of different harmonic current contents and different harmonic current frequencies on the distribution of stress field in the transformer core are analyzed. The simulation analyzes the distribution of stress field in the transformer core under the condition of constant rated current with different harmonic current contents and different harmonic current frequencies. The simulation results show that when the RMS value of rated current is kept constant, increasing the superimposed harmonic current content leads to a linear growth trend in the maximum stress value of the transformer core under the action of harmonic currents of different frequencies. However, there is a difference in the magnitude of increase in the maximum stress value of the transformer core under the action of different frequencies of harmonic currents.

I. Introduction

With the application of new transmission technologies, a large number of harmonics have appeared in the power system, and these harmonics cause vibration of electrical equipment, such as motors and transformers, and generate great noise, which greatly increases the failure rate of the equipment. For power transformers, implementing online monitoring and fault diagnosis technology can effectively reduce transformer failure rates and reduce operating costs [1]. The iron core is one of the main components of the transformer, and plays a crucial role in the electromagnetic performance and mechanical strength of the transformer. Equipment troubleshooting data reports over the years have shown that core failures often lead to a variety of transformer failures such as vibration, noise and structural loosening, etc. [2] Therefore, analyzing the vibration characteristics of the iron core is a very important part of condition monitoring of large power transformers, and has received widespread attention.